Category: Crafting Techniques

In leathercraft, a divider is used to mark a hand-stitching guideline at a consistent distance from the leather edge. A consistent divider line helps position the chisel accurately and keeps the finished hand-stitching line parallel to the edge.

A divider is not simply a tool for drawing a line on leather. Its spacing must be set according to the type of chisel being used, while the position of the guide leg, direction of movement, and applied pressure must remain consistent.

At Leather Studio YEGAK, we generally set the divider spacing to 2 mm when using a European-style slanted pricking iron and 2.5 mm when using a Japanese-style diamond chisel.

Divider Spacing Varies According to the Chisel Type

Set the divider spacing to 2 mm when using a European-style slanted pricking iron. Set it to 2.5 mm when using a Japanese-style diamond chisel.

This spacing is the distance between the leather edge and the hand-stitching guideline. If the same divider spacing is used for every chisel type, the proportion between the punched holes and the leather edge may change.

Before using the divider, first decide which type of chisel will be used. After identifying whether it is a European-style slanted pricking iron or a Japanese-style diamond chisel, set the spacing to 2 mm or 2.5 mm accordingly.

The chisel type and divider spacing must be selected together to create a balanced proportion between the leather edge, punched holes, and hand-stitching line.

Place One Divider Leg Outside the Leather Edge

When marking a line with a divider, do not place both legs on the leather. Position one leg outside the leather edge and allow only the other leg to touch the leather surface.

The leg outside the leather acts as a guide that follows the shape of the edge. The inner leg resting on the leather marks the hand-stitching guideline while maintaining the set distance from the guide leg.

With the outer leg resting against the leather edge, move the divider straight downward. The inner leg on the leather will then create a line parallel to the edge.

If the outer leg moves away from the edge or slips onto the leather, the spacing may change. Pressing the outer leg too firmly against the edge can also shift the leather or make the divider spacing narrower.

Apply Moderate Pressure When Using the Divider

Applying heavy pressure to create a darker line is not the correct way to use a divider. If the divider is pressed too firmly, the actual distance of the marked line may become narrower than the set spacing.

The marking leg can dig into the surface and scratch or gouge the leather. A deep mark of this kind may remain visible even after punching and hand stitching are completed.

The divider only needs to create a shallow, consistent line that remains visible on the leather surface. Apply just enough pressure to identify the punching position without cutting deeply into the leather.

On unfamiliar leather or leather with a soft surface, the depth of the mark can vary significantly depending on the pressure. Test the divider on a scrap of the same leather before marking the actual piece.

Move the Divider Straight Along Straight Sections

Along a straight section, place one leg outside the leather edge and move the divider straight downward.

Twisting or rotating the divider while marking can cause the position of the marking leg to shift. Keep the outer leg following the leather edge steadily so the inner leg creates a line at a consistent distance.

Work at a steady speed while checking that the outer leg remains in contact with the leather edge. If the divider moves away from the edge, reposition it accurately before continuing instead of forcing it back onto the existing line.

Rotate the Workpiece, Not the Divider, Along Curves

Do not rotate the divider itself to follow a curved section. Rotating the tool by hand can shift the positions of the outer and inner legs, causing the line spacing to become narrower or wider.

Even along a curve, move the divider straight in the same way as on a straight section. Rotate the workpiece gradually to follow the direction of the curve.

Keep one leg outside the leather edge and move the divider straight. Rotate the workpiece slightly, then move the divider again in the same direction. The inner leg will naturally create a divider line that follows the curve of the workpiece.

The tighter the curve, the less the workpiece should be rotated at one time. Use short divider movements and rotate the workpiece gradually to produce a smooth curved line without sudden changes in spacing.

The key is not to turn your wrist in an attempt to draw the curve with the divider. Keep the divider moving straight and rotate the workpiece to follow the curved direction.

Check the Spacing and Depth After Marking

After marking the complete divider line, inspect its condition before punching.

Check whether the distance between the leather edge and the line remains consistent from beginning to end. Inspect curved sections for inward or outward shifts, and confirm that the line has not cut or scratched too deeply into the leather surface.

Confirm that the spacing remains at 2 mm for sections punched with a European-style slanted pricking iron and 2.5 mm for sections punched with a Japanese-style diamond chisel.

After marking the divider line, learn how to position the chisel against the line and maintain the correct punching angle in How to Use European-Style Pricking Irons: No. 7 and No. 9 Spacing and Correct Punching Positionfor the next step.

Common Mistakes Made by Beginners

The first mistake is using the same divider spacing without checking the chisel type. As a general guideline, use 2 mm for a European-style slanted pricking iron and 2.5 mm for a Japanese-style diamond chisel.

The second mistake is placing both divider legs on the leather. One leg should rest outside the leather edge while the other leg marks the guideline on the surface.

The third mistake is applying excessive pressure to make the line more visible. Too much pressure can narrow the spacing and deeply scratch the leather surface.

The fourth mistake is rotating the divider to follow a curve. Keep the divider moving straight and rotate the workpiece in the direction of the curve.

The fifth mistake is punching immediately without checking the spacing and depth of the marked line. Once holes are punched along an incorrect line, correcting their position becomes difficult.

An Accurate Divider Line Determines the Hand-Stitching Position

An accurate hand-stitching line is not determined only during punching. It begins with setting the divider spacing and creating a guideline parallel to the leather edge before using the chisel.

Set the spacing to 2 mm for a European-style slanted pricking iron and 2.5 mm for a Japanese-style diamond chisel. Place one divider leg outside the leather edge and allow the other leg to mark the line on the leather.

Move the divider straight without applying excessive pressure, and rotate the workpiece rather than the divider along curves. Following these principles creates a hand-stitching guideline that remains consistently spaced from the leather edge across both straight and curved sections.

In leathercraft, a pricking iron is used to create hand-stitching holes with consistent spacing and direction. Even when the same pricking iron is used, the position of the holes and the appearance of the finished hand-stitching line can vary depending on how the tool is aligned with the divider line and the angle at which it is held.

At Leather Studio YEGAK, we use No. 7 and No. 9 European-style pricking irons. The No. 7 has 3.8 mm tooth spacing, while the No. 9 has 3.0 mm tooth spacing. We mainly use two-tooth and seven-tooth versions.

Rather than choosing a pricking iron based only on its number, check its actual tooth spacing, tooth shape, the size of the project, and the thickness of the leather. When punching, it is especially important to hold the pricking iron at a 90-degree angle from the beginning and align its teeth precisely with the left side of the divider line.

The Exact Purpose of a European-Style Pricking Iron

A European-style pricking iron is used to create evenly spaced hand-stitching holes along a line marked with a divider. Its purpose is not simply to make holes in leather, but also to maintain consistent spacing, slant, and direction throughout the hand-stitching line.

If the pricking iron moves away from the divider line, the hand-stitching line will not remain parallel to the leather edge. If the punched holes shift from side to side, the finished line can look uneven even when the hand stitching is completed with consistent tension.

When using a pricking iron, accurately setting its position and angle is more important than applying excessive striking force.

No. 7 and No. 9 Pricking Irons Used in Our Workshop

The No. 7 European-style pricking iron used at Leather Studio YEGAK has 3.8 mm tooth spacing. The No. 9 pricking iron has 3.0 mm tooth spacing.

Do not determine the spacing from the No. 7 or No. 9 designation alone. Numbering and actual tooth spacing can vary between manufacturers and products, so always check the stated spacing before purchasing a pricking iron.

In our workshop, we mainly use two-tooth and seven-tooth pricking irons. A seven-tooth iron is used to punch relatively long straight sections at consistent intervals, while a two-tooth iron is used for curves and sections where the direction changes.

For guidance on choosing thread thickness and punching spacing together, read [The Relationship Between Thread Thickness and Pricking-Iron Spacing: How Stitch Proportion Affects Quality]for more details.

Align the Pricking Iron with the Left Side of the Divider Line

First, use a divider to mark the guideline for hand stitching. Before punching, position the teeth of the pricking iron along the left side of the divider line and check their placement.

If the pricking iron is placed roughly in the center of the line or covers the line while punching, the hole positions may become inconsistent. The relationship between the teeth and the divider line must remain consistent from the first set of holes.

When positioning the pricking iron, do not look only at the upper part of the handle. Check the actual position of the teeth where they touch the leather. Even if the handle appears to be aligned with the line, the hand-stitching holes will fall outside the line if the teeth extend beyond the divider mark.

Hold the Pricking Iron at 90 Degrees from the Beginning

The pricking iron must always be held at a 90-degree angle to the leather surface. It should remain vertical from front to back and from side to side so that the hole positions remain consistent on both the front and back of the leather.

If the pricking iron is tilted inward or outward while punching, the hole positions on the front and back of the leather may not match. On thick leather or sections made from several glued layers, even a slight tilt can create a larger positional difference on the back.

A common beginner mistake is to tilt the pricking iron outward to align it with the divider line and then straighten it to 90 degrees immediately before punching.

At first, the teeth may appear to be aligned with the line. However, as the tilted pricking iron is straightened, the teeth move outward. As a result, they cross the divider line and create the hand-stitching holes farther outward than intended.

The pricking iron should therefore be held at 90 degrees first. While maintaining that angle, align its teeth with the left side of the divider line. Do not align the position first and then change the angle.

Use a Seven-Tooth Pricking Iron for Consistent Straight Sections

On relatively long straight sections, a seven-tooth pricking iron creates several evenly spaced holes at once.

When punching, hold the pricking iron at 90 degrees and align it with the left side of the divider line before striking. After punching and moving to the next position, maintain the same angle and alignment standard.

Even on a long straight section, do not rush through the punching. Check that the pricking iron remains vertical each time. If your hand or body position becomes uncomfortable, do not continue with the tool tilted. Reposition the workpiece and restore the 90-degree angle before continuing.

Follow Curves with a Two-Tooth Pricking Iron and Rotate the Workpiece

For a curve, punch once at a time with a two-tooth pricking iron and rotate the workpiece gradually to follow the direction of the divider line.

Do not tilt the pricking iron sideways or twist your wrist to follow the curve. Keep the tool at 90 degrees and rotate the workpiece to maintain the correct relationship between the teeth and the divider line.

The tighter the curve, the less you should try to change direction in a single movement. Punch once with the two-tooth iron, rotate the workpiece slightly, and then punch again.

The teeth must remain aligned with the left side of the divider line throughout this process. Even as the workpiece rotates, the vertical angle and alignment position must remain consistent so that the holes follow the curve naturally.

Overly Sharp Teeth Can Tear the Ends of the Holes

A pricking iron should pass cleanly through the leather, but excessively sharp teeth are not always better.

If the teeth are too sharp, the beginning and end of each punched hole can split and tear sharply. If the hole extends farther than necessary or develops small tears at both ends, the marks may remain clearly visible even after hand stitching.

Thin or soft leather can be especially vulnerable to overly sharp teeth. Before using a new or recently sharpened pricking iron on a finished piece, test it on a scrap of the same leather.

During the test, check whether the pricking iron passes through the leather without excessive force, whether the beginning and end of each hole remain clean, and whether the holes spread more than necessary when the thread is tightened.

The teeth should not simply be sharpened as much as possible. They should be maintained so that they pass cleanly through the leather without tearing either end of the holes.

What to Check When Choosing a European-Style Pricking Iron

When choosing a European-style pricking iron, check the actual tooth spacing rather than relying only on the tool number. The tools used in our workshop have 3.8 mm spacing for No. 7 and 3.0 mm spacing for No. 9, but products from other manufacturers may use different spacing for the same numbers.

For punching both straight lines and curves, it is best to prepare matching two-tooth and seven-tooth pricking irons with the same spacing and tooth shape. If their spacing or tooth shapes differ, the holes may change in appearance where straight and curved sections meet.

Check that the teeth are arranged evenly in a straight line and that each tooth has a consistent length and shape. When the handle is held upright, the teeth should also stand securely perpendicular to the leather surface.

Dull teeth require greater force and may compress or deform the leather. On the other hand, overly sharp teeth may tear the beginning and end of the holes. Judge the condition of the tool by testing it on scrap leather.

Common Mistakes Made by Beginners

The first mistake is aligning the pricking iron with the divider line while the tool is tilted. When the tilted tool is later straightened to 90 degrees, its teeth can move across the divider line.

The second mistake is positioning the tool by looking only at its handle. The true reference is the relationship between the teeth touching the leather and the divider line.

The third mistake is using the same number of teeth for both straight lines and curves. Curves should be punched one step at a time with a two-tooth pricking iron while the workpiece is rotated to follow the line steadily.

The fourth mistake is tilting the pricking iron sideways to follow a curve. Keep the tool at 90 degrees and rotate the workpiece instead.

The fifth mistake is using a new pricking iron directly on the finished piece without testing it. Because excessively sharp teeth can tear the beginning and end of the holes, test the tool first on a scrap of the same leather.

How to Maintain and Store Pricking Irons

After use, remove leather dust and debris from between the teeth. Leather fragments trapped between the teeth can affect the shape and depth of the next set of holes.

Store pricking irons in a dry place to prevent rust. When they are not in use, protect the teeth with a cover so they do not strike other tools.

Dropping a pricking iron can bend the tips or damage individual teeth. Misaligned teeth are difficult to position accurately against a divider line, so check that all the teeth remain evenly aligned before use.

Do not sharpen the teeth excessively simply because the tool does not cut easily. After any maintenance, test the pricking iron on scrap leather and confirm that the beginning and end of the holes do not tear.

Accurate Punching Requires Both Correct Position and Angle

Using a European-style pricking iron accurately requires more than selecting the tooth spacing and number of teeth. Hold the tool at 90 degrees from the beginning, then align its teeth with the left side of the divider line while maintaining that angle.

Use a seven-tooth pricking iron to maintain consistent spacing along straight sections. For curves, punch one step at a time with a two-tooth iron while rotating the workpiece to follow the line. Keep the pricking iron vertical instead of tilting it along the curve.

The condition of the teeth must also be checked. Teeth that are too dull can compress and deform the leather, while teeth that are too sharp can tear the beginning and end of the punched holes.

An accurate hand-stitching line is not created only after hand stitching begins. It is already determined when the pricking iron is aligned precisely with the divider line and used at a 90-degree angle.

Accurate cutting in leathercraft directly affects the shape and cut edges of the finished piece. Even when the same pattern is used, the result can vary depending on how the cutting knife is held, the angle of the blade, and how the pattern is secured.

A cutting knife is more than a tool for simply cutting leather. It transfers the shape of a completed paper pattern accurately onto the leather, so you must learn both how to keep the blade against the pattern edge and how to move the workpiece.

Before using a cutting knife, first review [How to Make a Leathercraft Pattern: From Blank Pattern Paper to a Finished Pattern and Leather Cuttingto understand the pattern-making process.

The Exact Purpose of a Leathercraft Cutting Knife

A leathercraft cutting knife is used to cut leather accurately by following the outline of a completed paper pattern. At Leather Studio YEGAK, we do not use a ruler when cutting leather. We place a firm handmade paper pattern on the leather and cut along its edge.

The purpose of a cutting knife is not limited to separating a piece of leather. It helps the cut leather match the pattern, keeps the cut edge close to a vertical angle, and preserves the intended shapes of straight lines and curves.

If the leather is not cut accurately, its edges may not align after gluing, or excessive edge correction may be required. Cutting should therefore be approached as a stage that already determines the final shape of the piece.

How to Use a Cutting Knife in Actual Leatherwork

First, place the completed paper pattern on the section of leather to be cut. Position a pattern weight in the center to prevent the pattern from moving, and use your other hand to press down near the area where the knife will pass.

Because a pattern can move easily on chrome-tanned leather, apply a small amount of leather adhesive to the edge of the paper pattern and place it on the leather as if lightly attaching it. Placing a pattern weight on top helps prevent the pattern from shifting during cutting.

Keep the blade firmly against the edge of the paper pattern. If there is a gap between the blade and the pattern, the leather will be cut larger than the pattern. If the blade moves underneath the pattern edge, the leather may be cut smaller than intended.

Press down near the cutting area, but never place your fingers in the path of the blade. Do not try to hold down the entire pattern at once. Reposition your hand and the pattern weight securely as you move to each cutting section.

Correct Hand Position and Blade Angle

Hold the cutting knife so that your arm follows the cutting direction naturally without bending your wrist excessively. Gripping the handle too tightly can stiffen your wrist and cause the blade to move away from the pattern edge.

Do not hold the blade completely upright. Because the tip of the cutting knife is formed at an angle, holding the knife vertically can produce a slanted cut edge.

Tilt the knife approximately 10 degrees outward from the pattern. This compensates for the angled shape of the blade tip and helps create a leather edge that is close to a precise 90-degree angle.

The approximate 10-degree angle is not an absolute rule that applies identically to every knife. It is based on the shape of the blade tip used in our workshop. If your blade has a different shape, make a test cut on a scrap of leather and inspect the resulting cut edge.

Cut Curves by Connecting Short Straight Cuts

When cutting a curve, forcing the knife around the curve or twisting your wrist in an attempt to complete it in one motion can cause the blade to move away from the pattern edge.

Think of circles and curves as shapes made from a continuous series of short straight lines. Make one short straight cut, rotate the workpiece approximately 5 degrees, and make another short straight cut. Repeating this process allows you to cut a curve accurately without forcing the blade to turn.

Rather than forcing the knife to change direction, rotate the workpiece and pattern a little at a time. After each short cut, check that the blade remains firmly against the pattern edge.

How to Check Cutting Accuracy

After cutting, keep the pattern and leather aligned and inspect them from both the front and back.

When viewed from the front, no leather should be visible beyond the edge of the paper pattern. When the piece is turned over, no part of the paper pattern should be visible beyond the edge of the leather.

If leather is visible from the front, the leather has been cut larger than the pattern. If the paper pattern is visible from the back, the leather has been cut smaller than the pattern. The pattern and leather match accurately only when neither one extends beyond the other from either side.

Common Mistakes Made by Beginners

The first mistake is cutting without securing the pattern sufficiently. If you only place a weight in the center and do not press down near the cutting area, the pattern edge may move under the pressure of the knife.

The second mistake is cutting with the blade positioned away from the pattern edge. Even a small gap between the blade and the pattern can change the final dimensions of the leather.

The third mistake is holding the knife completely upright. If the cutting knife has an angled blade tip, holding it vertically may prevent the cut edge from forming an accurate 90-degree angle.

The fourth mistake is twisting both the wrist and the knife in an attempt to cut a smooth curve in one motion. Curves should be cut by rotating the workpiece little by little and connecting a series of short straight cuts.

The fifth mistake is continuing to use a dull blade. A dull blade requires more force, which can cause it to move away from the pattern edge or leave a rough cut surface.

What to Check When Choosing a Leathercraft Cutting Knife

When choosing a cutting knife, first check whether the blade is held securely rather than focusing on its price or appearance. If the blade moves inside the handle, it will be difficult to maintain a consistent cutting line even when the knife is held against the pattern edge.

The handle should not feel excessively light or slippery in your hand. Choose a shape that reduces strain on your fingers and wrist during extended use and allows you to control the cutting direction steadily.

If the knife allows you to adjust how far the blade extends, check that its locking mechanism works securely and prevents the blade from sliding back into the handle during use.

For a knife with replaceable blades, it is also important to check whether replacement blades are readily available. Accurate and safe cutting requires replacing a dull blade when necessary rather than continuing to use it for too long.

You should also examine the shape of the blade tip. The angle at which you hold the knife may need to change depending on how the tip of the blade is formed.

How to Maintain and Store a Cutting Knife

After finishing your work, remove any leather dust and adhesive remaining on the blade. Hardened adhesive can create resistance during cutting and prevent the leather edge from being cut cleanly.

Store the knife in a dry place to prevent rust from forming on the blade. Retract a replaceable blade completely into its handle when it is not in use, and always place a protective cover over a fixed blade.

Check whether the blade needs to be replaced if it no longer passes smoothly through the leather or requires more force than before. You should also inspect the blade when the cut edge becomes rough or the knife feels as though it is pushing the leather rather than cutting through it.

Store new and used blades separately. Wrap discarded blades in paper or tape so that the sharp edges are not exposed. When possible, use separate knives for cutting pattern paper and cutting leather.

Accurate Cutting Begins with Proper Tool Use

Purchasing a good cutting knife alone does not guarantee accurate cutting. The pattern must be secured against movement, the blade must remain firmly against the pattern edge, and the knife must be held at an angle suited to the shape of its blade tip.

Learning to rotate the workpiece gradually and connect short straight cuts instead of attempting to cut a curve in one motion makes it possible to cut complex patterns more steadily.

After cutting, confirm that no leather is visible beyond the pattern from the front and that no paper pattern is visible beyond the leather from the back. Cutting is complete only after this check confirms that the pattern and leather match accurately.

Leathercraft patterns do not begin as sheets with preprinted shapes and markings. A large blank sheet of pattern board is purchased, cut to suit the item being made, and then shaped by hand into the required pattern.

The pattern board is initially purchased as a large blank sheet approximately half the size of a full sheet, with no lines or text printed on it. It is cut to the required size, shaped using cross-folding and straight-line principles, and then completed by adding the markings needed to make the item.

The Purchased Pattern Board Is Material for Making a Pattern, Not a Finished Pattern

The purchased pattern board is a firm sheet with no markings. At this stage, it is not a finished pattern that can be placed on leather for cutting, but the basic material used to create a pattern in the required shape.

The entire large sheet is not used as it is; instead, it is cut according to the size of the item and its components. A smaller section is prepared for a small component, while a larger section is prepared for a wide component such as a bag body panel.

If the board is cut without considering the required size, there may not be enough space to complete the pattern. Conversely, preparing an unnecessarily large piece can make it difficult to fold and handle while also wasting pattern board.

Cross-Folding and Straight Lines Establish the Pattern Shape

Once the pattern board has been cut to the required size, it is shaped using cross-folding and straight-line principles. Instead of drawing a complex outline immediately, the pattern’s dimensions and shape are established through the relationship between the folded references and straight lines.

When folding the board, check that the sections intended to meet are aligned accurately. If the fold is misplaced, the pattern created from that reference may also become inaccurate.

Straight lines provide the basic references that determine the pattern’s dimensions and shape. These references make it possible to create the required pattern while checking the relationships between the left and right sides and between the upper and lower sections.

The Finished Pattern Includes the Markings Required for Making the Item

Although the pattern board is blank when purchased, the finished pattern contains the markings required for making and assembling the item. A blank sheet of pattern board and a finished pattern used to cut leather are therefore two different stages.

The types and positions of markings on a finished pattern vary according to the item’s structure and construction method. Rather than placing identical markings on every pattern, the maker identifies and marks the positions that must be checked during the actual work.

These markings do more than indicate the outline used to cut the leather. They provide working references that help position each cut component correctly during the following stages and confirm the relationships between multiple components.

## Leather Is Cut with a Finished Pattern, Not a Blank Sheet of Pattern Board

Leather is cut using a pattern whose shape and working markings have been fully completed. The finished pattern is placed in the appropriate position on the leather, secured so that it cannot move, and used as the guide for cutting along its edge.

When cutting chrome-tanned leather, apply a small amount of leather adhesive along the edge of the paper pattern and position it as though lightly attaching it to the leather. Place a paperweight in the centre and press down by hand near the area where the knife is moving so that the pattern does not shift.

Keep the blade in contact with the edge of the pattern, but do not hold the knife perfectly upright. Because of the angled shape of the knife tip, tilt the knife approximately 10 degrees away from the pattern to produce an accurate 90-degree cut edge.

Do not cut curves and circular sections by turning the knife through the entire shape in one continuous motion. Make a short straight cut, rotate the workpiece by approximately 5 degrees, and repeat the process to form the curve from connected straight cuts.

After cutting, compare the pattern and leather from both the front and back. The pattern shape has been transferred accurately when no leather is visible beyond the pattern from the front and no part of the pattern is visible beyond the leather from the back.

For detailed guidance on the knife angle and curve-cutting method, see How to Cut Chrome-Tanned Leather with a Pattern: Adhesive Fixing, a 10-Degree Knife Angle, and Curve-Cutting Principles.

A Pattern Is a Working Standard for Making the Same Item Repeatedly

A pattern is more than a template for cutting the outer shape of the leather. It becomes a finished working pattern only after the blank pattern board has been cut to size, shaped using cross-folding and straight lines, and completed with the markings required for the work.

An accurate finished pattern helps maintain consistent component dimensions and shapes when the same item is made again. Because a small error in the pattern can become more noticeable during leather cutting and assembly, the pattern shape and markings must be checked before the leather is cut.

For the complete workflow from bag design and pattern making to assembly, see The Complete Leather Bag-Making Process: From Design and Pattern Making to Assembly and Finishing.

Making a leathercraft pattern is not simply a matter of drawing an outline on blank paper. It is the process of dividing a large sheet of pattern board to suit the item, creating an accurate shape through cross-folding and straight-line principles, and adding the markings required to establish the final cutting standard.

Testing the working conditions on a scrap piece of leather before making the final item can reduce mistakes during the main project. Even with the same type of leather, the results of cutting, gluing, and hand stitching may vary depending on its thickness, surface treatment, oil content, and dyeing condition.

Scrap leather is not simply leftover material. It is a test piece that allows you to check in advance whether the leather and materials intended for the final item work well together. When using unfamiliar leather, adhesive, thread, or needles, it is safer to test them before beginning the final project.

Prepare the Test Piece Under the Same Conditions as the Final Item

A test performed on an unrelated piece of leather cannot provide a reliable standard for the final item. The test piece should be cut from the same leather intended for the final project. If the leather will be skived, the test piece should also be prepared at the same final thickness.

A gluing test piece should use the same grain and flesh surfaces that will be joined in the final item. A hand-stitching test piece should have approximately the same number of leather layers and total assembled thickness as the final item.

When preparing the test piece, match the following conditions to the final project:

• Leather type and thickness
• Skiving area and final thickness
• Number of overlapping leather layers
• Type of adhesive used
• Hand-stitching hole spacing
• Needle and thread size
• Thread colour
• Edge-finishing method

If the conditions of the test piece differ from those of the final item, the results may also be different.

Use a Cutting Test Piece to Check the Knife Angle and Cut Edge

When cutting chrome-tanned leather, use a handmade heavy paper pattern. Apply a small amount of leather adhesive along the edge of the paper pattern and position it as though lightly attaching it to the leather. Then place a paperweight in the centre of the pattern to secure it.

Press down by hand near the area where the knife is moving so that the pattern does not shift. Because of the angled shape of the knife tip, tilt the knife approximately 10 degrees away from the pattern to produce an accurate 90-degree cut edge.

Do not cut a curve or circle by turning the knife through the entire shape in one continuous motion. Make a short straight cut, rotate the workpiece by approximately 5 degrees, and then make another straight cut. Continue repeating this process. This method follows the principle that a circle can be created by continuously connecting short straight lines.

After cutting, inspect the result from both the front and the back. The piece has been cut accurately when no leather is visible beyond the paper pattern from the front and no part of the paper pattern is visible beyond the leather from the back.

You can find the complete process in the following article: How to Cut Chrome-Tanned Leather with a Pattern: Adhesive Fixing, a 10-Degree Knife Angle, and Curve-Cutting Principles.

Use a Gluing Test Piece to Check Leather and Adhesive Compatibility

Depending on the type of leather, the flesh side may contain loose leather fibres or absorb adhesive quickly. If the surface contains a large amount of oil or wax, the adhesive you normally use may not form a reliable bond.

Prepare two pieces of the same leather intended for the final project and apply the adhesive using the same method you will use on the final item. The amount of adhesive, application area, drying time, and pressing method should also match the final working conditions.

Align the two test pieces accurately and apply even pressure across the entire bonding surface. Do not judge the bond only by whether the pieces hold together immediately after gluing. After the adhesive has cured for the time specified for the product, check whether the edges lift or the layers shift.

If the bonded surfaces separate, check the surface condition, adhesive compatibility, application amount, drying time, and pressing conditions before applying more adhesive.

Detailed criteria for checking gluing problems can be found in the following article: Why Glued Leather Layers Separate in Leathercraft: Surface Preparation, Drying Time, and Pressure.

Use a Hand-Stitching Test Piece to Check the Thread and Needle Combination

Prepare the hand-stitching test piece with the same leather thickness and overlapping structure as the final item. Passing thread through a single layer of leather does not accurately show the resistance created by multiple layers or the final appearance of the hand-stitched line.

Make holes in the test piece using the same spacing intended for the final item, and then hand-stitch it with the needles and thread you plan to use. Check whether the hand-stitched lines are consistent on both the front and back, and whether the thread is too thick or too thin for the leather thickness.

A thread colour may appear different when viewed on its own and when hand-stitched into leather. Even colours from the same family may either emphasise the hand-stitched line or blend naturally into the leather depending on the difference in value between the leather and thread. Always check the colour on the actual leather.

For a standard section, prepare thread at approximately four times the length to be hand-stitched. For a long straight section, the amount may be reduced to approximately 3.5 times the length. For a short section, prepare more than four times the length because the thread required for attaching the needles and finishing makes up a larger proportion of the total. Additional thread should also be prepared for thick leather or sections where the thread passes through several layers.

Detailed thread-length guidelines can be found in the following article: How to Calculate Thread Length for Leathercraft Saddle Stitching: 4×, 3.5×, and Thickness Adjustments.

Record the Test Results to Create a Standard for Future Projects

If the materials and working conditions are not recorded, the same tests will have to be repeated for the next project. Record the following information on the back of the test piece or on a separate record sheet:

• Leather type and thickness
• Thickness after skiving
• Type of adhesive
• Adhesive drying and curing times
• Hand-stitching hole spacing
• Needle type and size
• Thread type, size, and colour
• Length of the hand-stitched section
• Actual length of thread used
• Cutting, gluing, and hand-stitching results

Record the following information on the back of the test piece or on a separate record sheet: An unsuccessful test piece becomes a useful working reference that helps prevent the same mistake from being repeated.

A Small Test Piece Reduces Losses During the Final Project

Preparing a scrap test piece requires a small amount of time and material. However, this loss is far smaller than having to redo the final item because of an inaccurate cut edge, a separated bond, or an unsuitable combination of leather and thread.

Test pieces are not only for beginners. They are part of a professional checking process used to evaluate working conditions accurately when introducing new leather or materials.

Checking cutting, gluing, and hand-stitching conditions on a small test piece and recording the results before beginning the final project helps maintain a consistent level of craftsmanship.

Accurately cutting chrome-tanned leather requires more than simply placing a handmade heavy paper pattern on the leather. Because chrome-tanned leather is soft and flexible, even slight movement of the pattern or leather while cutting can alter the dimensions of the cut piece.

I apply a small amount of leather adhesive along the edge of the paper pattern and position it as though lightly attaching it to the leather. I then place a paperweight in the center and press down by hand near the area where the knife is moving while cutting along the edge of the pattern.

The important point in this method is not to hold the knife perfectly upright. Because the tip of the cutting knife has an angled shape, the knife must be tilted approximately 10 degrees away from the pattern to produce a clean 90-degree cut edge.

Temporarily Adhere the Pattern When Cutting Chrome-Tanned Leather

Chrome-tanned leather is often softer and more flexible than vegetable-tanned leather, so simply placing a pattern on top may allow either the leather or the pattern to shift during cutting.

To prevent this, apply a small amount of leather adhesive along the edge of the paper pattern. Do not spread adhesive across the entire pattern; use only enough to prevent the edges from lifting or moving during cutting.

Place the adhesive-coated pattern on the leather, confirm its exact position, and press it down lightly. Once the pattern is secured to the leather, place a paperweight in the center to prevent the entire pattern from rotating or shifting.

Excessive adhesive may leave residue on the leather surface or cause problems when the pattern is removed. Before cutting the actual piece, test the amount of adhesive on a scrap of the same chrome-tanned leather.

Secure the Pattern with Both a Paperweight and Your Hand

The leather adhesive prevents the pattern edge and leather from sliding against each other. The paperweight placed in the center prevents the entire pattern from rotating or moving significantly.

Press down by hand near the area where the knife is moving so that the section currently being cut does not lift. The paperweight secures the center, while your hand prevents movement along the edge being cut.

As the knife moves forward, the hand pressing the pattern must also move to the next position. Do not move your hand while the knife is still cutting. Stop the knife first, reposition your hand, press the pattern down again, and then continue cutting.

Always keep your fingers inside the pattern and away from the knife’s path. Press close enough to the cutting area to secure the pattern, but keep your fingers safely within the pattern edge.

Keep the Knife Blade Against the Pattern Edge

After securing the pattern with adhesive and a paperweight, keep the knife blade in contact with the edge of the paper pattern throughout the cut.

If a gap forms between the blade and the pattern, the leather will be cut larger than the pattern. If the blade cuts underneath the pattern, the leather will be cut too small and the edge of the paper pattern may also be damaged.

Use the pattern edge as an exact cutting guide. Do not press the knife so forcefully against the pattern that it cuts into the paper; follow the outline with steady, controlled pressure.

Why the Knife Is Tilted Approximately 10 Degrees Outward

The cutting knife used in this method has an angled tip. If the knife is held perfectly upright against the leather surface, the actual cutting edge may pass through the leather at an angle and fail to produce a 90-degree cut edge.

To compensate for the angled tip, tilt the upper part of the knife approximately 10 degrees away from the pattern. This allows the angled cutting edge to pass through the leather while producing a cut surface close to a true 90-degree angle.

The approximate 10-degree angle is not a universal rule for every cutting knife. It is the working angle suited to the tip shape and sharpening condition of the knife used in this method.

When using a new knife or a blade with a different shape, make a test cut on scrap leather and inspect the cut edge. The correct angle should be determined by whether the actual leather edge forms a 90-degree angle, not by the knife’s appearance alone.

Cut Straight Lines Without Changing the Knife Angle

When cutting a straight line, keep the blade against the pattern edge and move it forward while maintaining the approximately 10-degree outward tilt.

If your wrist turns inward or outward during the cut, the edge angle may differ between the beginning and end. Instead of moving the knife by twisting your wrist, allow your arm to follow the cutting direction.

Do not overreach when cutting a long straight line. Stop the knife, reposition your body and the hand holding the pattern, and then continue cutting at the same angle.

Create Curves by Connecting Short Straight Cuts

A curve is not cut by sweeping or bending the knife around the curved edge of the pattern. Circles and curves can be understood as a continuous sequence of short straight lines.

First, cut a short section in a straight line. Then rotate the entire workpiece approximately 5 degrees without allowing the leather and pattern to shift against each other, and make another short straight cut.

Rotate the workpiece approximately 5 degrees again and cut the next straight section. Repeating this process connects the short straight cuts into a smooth line that follows the curve of the pattern.

The tighter the curve, the shorter each straight cut should be and the smaller each rotation should become. Rotating the workpiece too far or cutting overly long sections can create an angular curve or cause the blade to move away from the pattern edge.

The key is not to force the knife to twist through the leather to create a curve. Keep the knife moving in the same straight direction at the same tilt, and gradually rotate the workpiece with the leather and pattern attached to change the cutting direction.

Cut Circles Using the Same Principle

Cutting a circle is not a matter of drawing one continuous round line with the knife. It is done by repeatedly making a short straight cut, rotating the workpiece slightly, and making another straight cut.

For example, cut one short section in a straight line and then rotate the workpiece approximately 5 degrees. Cut another straight section of the same length and rotate the workpiece again.

Repeating this process consistently connects many short straight lines to form a circle. The length of each section and the amount of rotation must remain consistent to prevent any part of the circle from protruding or receding.

As with straight cutting, keep the knife tilted approximately 10 degrees away from the pattern. Even as the workpiece rotates, the relationship between the knife and the pattern edge must remain unchanged.

Connect Two Straight Cuts at One Exact Point to Form a Corner

At a corner where two straight lines meet, cut the first line precisely to the corner reference point and then lift the knife.

Rotate the workpiece and begin the second straight cut from the new direction. The two cutting lines must meet at one exact point on the corner of the pattern.

If the knife is left embedded in the leather and turned sharply around the corner, the tip may pass beyond the pattern or damage the pattern edge.

If the first and second cuts do not meet, leather fibers may remain at the corner. If either cut extends beyond the reference point, an unnecessary knife mark may remain on the finished piece.

Check Cutting Accuracy from Both the Front and Back

After cutting, do not judge accuracy by examining only the front surface. Check whether the outlines of the pattern and the cut leather match from both the front and the back.

First, inspect the front with the pattern still attached. No leather should be visible beyond the edge of the pattern. If leather is visible, the blade moved away from the pattern and cut outside the intended line.

Next, turn the cut piece over and inspect the back. No part of the paper pattern should be visible beyond the edge of the leather. If the pattern is visible, the blade cut inward and made the leather piece too small.

When the piece has been cut accurately, no leather will be visible outside the pattern from the front, and no pattern will be visible outside the leather from the back. The edges of the pattern and leather must align precisely on both sides.

Inspect the cut edge as well. It should form a 90-degree angle without leaning to either side so that the edges of multiple components align correctly during bonding and stitching.

Post-Cutting Checklist

• Is any leather visible beyond the edge of the pattern?
• Is any part of the pattern visible beyond the leather when viewed from the back?
• Do the outlines of the leather and pattern align precisely?
• Has the leather edge been cut at a 90-degree angle?
• Did the knife angle remain consistent from the beginning to the end of each straight cut?
• Is the curve free from angular or uneven sections?
• Are all sections of the circle connected consistently?
• Do the two straight cuts meet at one exact point at each corner?
• Did the pattern remain securely attached without shifting or lifting during cutting?
• Has the edge of the paper pattern remained undamaged by the knife?

Accurate Cutting Depends on Maintaining the Relationship Between the Pattern and the Knife

The key to cutting chrome-tanned leather with a pattern is to secure the pattern with leather adhesive and a paperweight while keeping the knife blade in contact with the pattern edge.

Instead of holding the knife perfectly upright, tilt it approximately 10 degrees away from the pattern to compensate for the shape of the cutting edge. Maintaining this angle allows the cut leather edge to form an accurate 90-degree angle.

Curves and circles do not require a separate sweeping knife motion. They are created by repeatedly making short straight cuts and rotating the workpiece approximately 5 degrees to connect those straight cuts into a continuous curve.

A deeper explanation of these cutting principles can also be found in “ Why Leathercraft Should Be Learned Through Principles, Not Just Techniques.”

When the leather has been cut accurately, no leather will be visible outside the pattern from the front, and no pattern will be visible outside the leather from the back. Only when both conditions are met can the pattern dimensions be considered accurately transferred to the leather.

Gluing in leathercraft is not simply a temporary step used to hold components together before stitching. If the bond is unstable, the cutting lines and stitch lines can become misaligned, the leather may shift during punching, and the layers or edges may separate after completion.

It is easy to assume that applying more adhesive will create a stronger bond. However, bond strength is not determined by the amount of adhesive alone. A stable bond requires suitable surface preparation, the correct type and amount of adhesive, proper drying time, even pressure, and sufficient curing time.

The following information is based on the contact adhesives commonly used in leathercraft. Because the recommended application method and drying time vary by product, always check the manufacturer’s instructions before use.

Inspect the Gluing Surfaces Before Applying Adhesive

If dust or loose leather fibers remain on the flesh side, the adhesive may stick to the debris instead of bonding directly with the leather fibers. The layers may initially appear secure but can separate when the leather is bent or the edges are finished.

Before applying adhesive, remove loose leather fibers with a soft brush or dry cloth. If the surface is extremely smooth or coated, lightly abrade only the area to be glued so that the adhesive can bond with the leather fibers.

Abrading too deeply can thin the leather and leave visible marks on the finished surface. The purpose of surface preparation is not to remove a large amount of leather but to create a suitable surface for a stable bond.

Leather containing a large amount of oil or wax may separate easily even when glued using the same method as ordinary leather. Instead of applying more adhesive, test the combination on a scrap of the same leather first.

More Adhesive Does Not Necessarily Create a Stronger Bond

Applying an excessively thick layer of adhesive increases the drying time and may allow the adhesive layer to shift internally. When the components are pressed together, the adhesive may also squeeze out around the edges, stain the leather surface, or interfere with edge finishing.

If too little adhesive is applied or some areas are left uncovered, lifting will begin where the bond is incomplete. Pay particular attention to edges, curves, and areas where several layers meet.

Instead of building up a thick adhesive layer, apply it thinly and evenly according to the product instructions. Because the porous flesh side of some leathers absorbs adhesive quickly, inspect the first coat and apply additional adhesive only where necessary.

Do Not Judge Drying Time by the Clock Alone

Many contact adhesives create a more stable bond when the required open time is observed instead of joining the surfaces immediately after application. If the adhesive is still too wet, the components may slide out of position and adhesive may squeeze out when the edges are pressed.

However, waiting too long beyond the recommended time can also reduce bonding performance. The actual condition varies according to the workshop temperature, humidity, application thickness, and the absorbency of the leather, so both the product instructions and the condition of the adhesive surfaces must be considered.

Do not apply the same drying time to every adhesive. Record the recommended open time and working time of each product, and use the results of test bonds made with the same leather as a reference for future projects.

The Surfaces Must Be Aligned Correctly at First Contact

Once two surfaces coated with contact adhesive touch, separating and repositioning them may be difficult. If the starting points and center points are misaligned and only the endpoints are forced to match, one component may stretch or wrinkles may form in the middle.

Adhesive should never be used to conceal incorrect pattern measurements or a difference in component lengths. If the endpoints do not match, recheck the cutting dimensions, stitch-line lengths, center points, and the direction in which the leather stretches before pulling the leather into position. How to Accurately Join a Leather Bag Body Panel and Gusset,” which explains why long curves are more reliably aligned by dividing them into smaller sections between reference points instead of gluing the entire perimeter at once.

Adhesive should never be used to conceal incorrect pattern measurements or a difference in component lengths. If the endpoints do not match, recheck the cutting dimensions, stitch-line lengths, center points, and the direction in which the leather stretches before pulling the leather into position.

Apply Even Pressure Across the Entire Glued Area

Pressing only the edges with your fingers may not apply sufficient pressure to the center or curved areas. Use a roller, press, or another tool suitable for the project so that the entire glued area makes even contact.

Place a protective material over the leather and control the pressure to avoid marking its surface. Strong pressure may alter the sheen or grain pattern of soft or heavily textured leather, so test the method on a scrap first.

The purpose of pressing is not to force adhesive out of the joint. It is to reduce gaps between the two surfaces and ensure that the adhesive makes even contact with both sides.

Initial Bonding and Full Curing Are Not the Same

The fact that the components no longer move immediately after gluing does not mean that the adhesive has fully cured. Bending, skiving, punching, or sanding the leather before sufficient curing can cause the glued layers to shift or separate at the edges.

The time required before proceeding to the next operation and the time required for full curing vary by product. In load-bearing areas, allow the adhesive to stabilize sufficiently before punching and stitching.

Adhesive is not a structural substitute for stitching. Areas exposed to repeated loads, such as handle attachments, straps, bag bottoms, and areas around metal fittings, must also use suitable stitching, rivets, screws, or reinforcement.

What to Check When Glued Leather Layers Separate

If the glued layers continue to separate, check the following before applying more adhesive.

• Are the bonding surfaces free of dust and loose leather fibers?
• Are oil, wax, or surface coatings interfering with the bond?
• Is the adhesive suitable for this type of leather and its intended use?
• Has the adhesive been applied evenly without any uncovered areas?
• Did you allow the adhesive to dry for the time specified by the manufacturer?
• Were the two components aligned correctly from the moment they were joined?
• Was even pressure applied across the entire bonding surface?
• Was the adhesive allowed to cure fully before proceeding to the next step?
• Is the bonded area repeatedly subjected to pulling or peeling forces after completion?

When using solvent-based adhesive, work in a well-ventilated area and follow all instructions concerning ignition sources and personal protective equipment.

A Good Bond Should Not Draw Attention in the Finished Work

Properly glued leather remains aligned during punching and stitching, and its multiple layers stay together like a single surface during edge finishing.

The key to leathercraft gluing is not using a large amount of strong adhesive. It is properly preparing the leather surfaces, applying the adhesive evenly, and observing the drying, pressing, and curing times required for the product.

Only when these basic steps are performed correctly will the stitch lines and edges remain aligned and the finished item retain its shape over time.