Prep for tooling
Leather stretches and deforms as you carve it, but there are steps you can take to limit this. I’ve been doing a lot of reading over the past few days in preparation for a fairly serious bit of tooling, just to make sure I had my thoughts in order, and there have been some changes since I first started reading the old books and Al Stohlman’s stuff.
For light tooling and stamping the leather won’t stretch much and you can just tool away, but in more serious tooling you need to prepare the leather a little more thoroughly. In basket weaving and geometric stamping, the leather will stretch and curl up around the edges as you work it, so your final dimensions will change and you may not be able to get it flat again. The curling is a real bitch to work around, and all this stretching means you aren’t getting as clean an impression as the leather runs away from the tool.
Once the carving is done you’ll need to do something about the stretch and curl factors. The trick is to glue the leather to something that won’t stretch or curl. in the old days, this meant rubber cement and posterboard, or if you happen to have a way to get it, old X-Ray film was said to be a great medium. In the last few years, however, folks figured out that packing tape works pretty well, and is easier to get and work with.
The steps below are an amalgamation of all the reading I have done:
- You need to ‘case’ the leather by getting it more thoroughly wet on both sides. Let it air out a bit and start to return to the lighter color, and then put it in a plastic bag – a freezer bag will work for smaller pieces, but for larger works (briefcases and such) you’ll need a trash bag. Fold the excess plastic under the piece to seal it closed and leave it on the table overnight or so. Sometimes it pays off to leave it a full 24 hours. This allows the leather to really soak in that moisture and soften up in preparation for the stamping.
- Once it has cased for a day the leather should be ready to go to work. Go ahead and pull the piece out, transfer your design and guidelines, and do any carving your design calls for. If the leather dries out too much, dampen it down with a sponge as needed.
- Now that you’re done carving, it’s time to tape it up. Use a thick, quality tape – the cheap thin stuff shreds when you try to pull it off, and the adhesive is less workable. Make sure the back of the piece is not too damp or wet (it should be mostly dry by this point) and lay your first strip down. Run it over with a glass slicker or a roller to make sure it sticks well, and then continue layering the tape – make sure you overlap a 1/4″ or so on each pass, and continue like this until you have covered the whole piece. A second layer should then be applied crosswise to make sure you’ve pinned it down if both directions.
- (Optional) If you’re really worried about the stretch or curl, some leather workers have gone an additional step by getting a piece of acrylic plastic 1/4″ thick or thicker, and then rubber cementing the tape-backed leather to the acrylic. The acrylic is hard enough that when placed onto your tooling slab you’ll still get a solid impression and the leather won’t get mushed about as you work it. The tape alone seems to work well for the folks I have read up on. In any case, by now you’re ready for tooling, so get to it.
- Grab a mallet and go to work, re-dampening the leather as needed. Don’t use too much water, as it will affect the tape. Stick to using a sponge at this point, or a mister. Try to keep your impressions as uniform as possible, and you should get nice clean imprints – the leather has nowhere to go but down at this point.
- Once you finish the tooling, allow the piece to dry a while and return mostly to the original color before you remove the tape. Turn the project upside-down and pull the tape off of the leather, rather than the other way around to avoid stretching it out after you went through all this. The tape should come off cleanly and leave just a slightly fuzzy nap to the leather.
I’ll be using this method myself on my next couple of projects – I had terrible stretching problems on the smartphone case I made a while back – I ended up re-soaking the leather and leaving it to dry under my slab for almost a week to get it flat again.