Blind tooling is the bookbinding term for what leatherworkers would simply call tooling. It's the process of using a heated device to impress a shape into a surface, usually of leather or vellum. Bookbinders call it "blind" to distinguish it from gold tooling, an art mostly developed by their craft.
There are two methods of blind tooling, wet and dry. Dry tooling produces a truly "blind" impression, indented but not colored. Tooling leather wet produces steam, which "cooks" and darkens the indentation. It's like branding the leather.
Blind tooling is one of the earliest techniques of cover decoration, with examples dating back to the first leather-bound volumes of the Fifth Century AD. The process was popular in Europe and the Islamic world until the gradual introduction of gold tooling. Although much supplanted by shinier, more glamorous techniques, blind tooling has never died out. It is still in use in fine binding today.
In addition to its role as a decorational effect, blind tooling is an important first step in some kinds of gold tooling.
How to Blind Tool
The instructions below assume you're using leather, though other materials can be used as well.
- The tools themselves, which will be used to make impressions in the leather.
- A stove or other heat source
You can get a special finishing stove, an electric hot plate with a rack around it to hold tools onto the heated surface. These are expensive. I use the gas stove in my kitchen, holding each tool in the flame in turn. I used to use a candle, but the soot tended to blacken the brass too much.
- Heat protection
It's a good idea to have something you can put hot things on nearby. Also, if you're tooling on a plain piece of leather rather than a book, you'll need to lay it on this before doing so. Otherwise the heat will pass through and damage your surface. I use a cork tile.
- A damp cloth to test the tool temperature.
This will get scorched, so don't use your best silk hanky.
- Something to tool, such as leather or vellum.
- Another scrap of what you're tooling, at least until you're a very good judge of tool temperature and don't need to try things out.
- wheat paste, if you're wet tooling.
What to Do
- Mark out your design.
- If your tools are not too finely detailed, you can tool straight through a sheet of thin onionskin paper, at least to make the initial impression. In that case, use the tools as rubber stamps on the paper to plan the design, and tool dry. (You can re-tool wet afterwards, without the paper, if you want darkened impressions).
- If you can't use a paper pattern, use a very fine pin to prick the leather at significant points. One way is to mark the locations of the tools themselves. Another trick is to mark the ends of the horizontal line they will be on with pinpricks, then use a marked-up piece of vellum to determine the position of the tool on the line.
- Dampen the leather if you're tooling wet.
Ordinary water won't stay on leather long enough to dampen it properly. The solution is to use wheat paste, diluted to a runny consistency. That way, the moisture won't run off before it soaks in.
Dampen on the entire leather surface, not just the area to be tooled, or you'll leave a watermark.
- Heat your tool
The temperatures required for tooling are relatively cool. The metal should be just hot enough to hiss when touched to your damp cloth. Try it out on your sample piece until you get the right temperature. Then reheat the tool slightly, touch it to the cloth, and go on to the next step.
Press the tool firmly onto the leather, rocking it slightly to make sure all the details make an impression. If you're wet tooling, the leather should hiss slightly but not scorch.
Once you put the hot tool to the leather, you're committed. If it's not straight now, comfort yourself with how handcrafted your piece looks. Don't try to reposition the tool; no crooked mark is worse than a dragged impression.
- Reheat and retool if the mark isn't dark enough.
Note that you can also use a piece of thread, rubbed vigorously back and forth, to blind tool lines on the spine of a book.