When binding a book with leather, the thickness measurement of the leather is important to know. Leather thickness can impact the book aesthetics as well as the mechanical operation. Thick leather spine hinges, for instance, can cause opening and closing issues for the cover boards. Or if the turn-in’s are too thick, the corners of the book suffer from build up of leather layers.
If you buy bookbinding leather, it is often cut thinner than saddle leather or thicker than leather clothing. Often the thickness of leather used to bind a book depends on the size of the book and the type of book board used. A 6”x9” book size might use a .65mm to .70mm with the edges that wrap around the book’s boards pared to a hairline thinness. Especially if that book will use leather onlays as surface decoration. Or if the book uses interior leather hinges for leather doublures.
Professional binders, who have worked with leather coverings consistently, can tell by feel if the thickness of the leather is correct for a binding application. Binders also rely on caliper gauges, when doing specific tasks, to give accurate measurements. For instance, if a leather spine hinge needs a .45mm to .5mm thickness, a caliper gauge helps reach the desired leather thickness during the paring process of the leather.
In this post you see a iGaging digital caliper gauge I bought a few years ago to help me accurately pare leather hinges to a specific thickness. An overly thin leather hinge is too weak to last under constant opening and closing of the covers. A too thick leather hinge not allow the covers to close properly. My digital caliper runs on a 3v lithium cell. This post talks about how to set the digital calipers to gauge the leather thickness. The interface is not the most intuitive and I am always forgetting how to do it.
Step one: Be sure to insert the battery into the tool. You will see there are 3 buttons on the digital gauge. The “mm/in/F” button enables you to choose, by toggling through the options with each button press, the measurement format in millimeters or inches with decimal point or inches with fractions. I always use the “mm” format. The “HOLD’” button toggles between holding the number readout in the display and releasing it. The “ON/ZERO” + “OFF…” button enables you to turn on the gauge, reset the 0 point measurement and turn the gauge off. Press the “ON/ZERO” + “OFF…” button. You should see the digital readout display “0.00”. Note: the upper “hooked” caliper arm is moveable and in the raised position. The lower straight caliper arm is stationary. When the readout is displaying 0.00 with the arms apart it means the 0 point as the widest distance between the two caliper arms.
If you press the hooked caliper arm down the readout will be in a negative number range. For my purpose, I need to reset the 0 point to read “0.00” with both caliper arms touching.
Step two: Press the upper hinged hooked caliper arm closed so that it touches the straight stationary caliper arm. Then press the “ON/ZERO” + “OFF…” button. The readout should reset to 0.00 as the caliper arms are together.
Step three: Release the moveable hooked caliper arm. Now you will see the readout registering in positive numbers. When you place a leather piece between the caliper arms and press lightly on the leather surface you will see readout display the leather thickness in millimeters.
This measurement you can recheck as you pare the leather to reach the desired thickness.
Note: to turn off the gauge you have to press the “ON/ZERO + OFF…” button and hold it down until the readout display turns off. Be sure to keep backup battery cells as they go quickly. Also, there are other brand models out there similar to this helpful tool.