All of the stamps we make are intended for use on NATURAL VEGETABLE TAN leather.
Ideally this needs to be 2mm thick or upwards - we engrave the designs approximately 1.5mm deep on the stamp which is enough to give a nice impression in any thickness of leather. It is often referred to as 'tooling leather'.
If the leather is only 1mm thick then you are likely to only achieve an impression 0.5mm deep, so this needs to be borne in mind when selecting your leather. With thin leather if you want to achieve a deeper impression then inserting someething like a 1mm thick sheet of silicone rubber beneath the leather can help drive the stamp deeper than the thickness of the leather.
How to stamp natural vegetable tan leather.
To achieve a deep and quality impression you can use a moist sponge or get a plant spray atomiser using tepid water and spray the face of the leather a few times then leave for 5 or 10 minutes so the moisture soaks into it properly. Don’t wet the back of the leather. This is known in the trade as 'casing'.
The ideal is for the surface to begin to go paler again (it is darker when wet) then it is ready for stamping. You don't have to hammer or press it as hard when damp either, as the leather is softened.
What happens is thet the water swells and softens the leather fibres and when you press the stamp in the fibres compress and go darker in colour and the moisture is forced into the adjoining fibres, making the leather bulge upwards into the cavities on the stamp. This results in a beautiful impression with nicely rounded raised sections around the stamped graphics.
The leather hardens as it dries and this 'locks' the impression in - next you can dye/stain and finish the piece.
Hand stamps - how big can I go??
We get a lot of people new to leather asking us to make hand/mallet stamps at a size too big to be suitable for use with a mallet. For use with vegetable tan leather we'd suggest something no bigger than 40mm x 40mm, but this very much depends on the area within the stamp which has to be pressed down.
In rough percentage terms, if 20% of the stamp area has to be pressed down then 40mm x 40mm would be OK. But if 80% of the area needs pressing down then that requires 4 times the force to achieve a good impression. So 40mm square would be too big and you'd need to reduce the size to no more than 30mm square.
For any situation where these sizes are bigger then we'd recommend getting an arbor press. We sell them so do get in touch for more details!
Testing your leather for stamping
Before committing to the purchase of a stamp if you are not using natural vegetable tan leather then it is useful to carry out a simple test on an offcut of your leather.
Place the offcut onto a solid smooth surface such as a granite block (this should also be on a solid bench with no 'give'). Then get a round headed nail about 4 inches long - the sort carpenters use - and place the round head on the surface of the leather at 90 degrees. Carefully strike the sharp end with a metal hammer and see what sort of impression you have created.
If it looks good then you won't be wasting your money buying a stamp. If the leather is thin you may need to cushion it between the granite and the leather with something soft like a couple of layers of felt or thin rubber.