Chemical Woodburning

By Sean Michael Ragan
Category: Science, Woodworking
Time Required: 1 hour
Difficulty: Easy

If you want to apply a maker’s mark or other repeated pyrograph to wooden goods, but can’t justify the expense of a custom branding iron, an indistinguishable effect can be achieved by applying a strong solution of ammonium chloride, for instance using a foam rubber stamp, followed by relatively mild heat.

On heating, ammonium chloride decomposes into ammonia gas and strong hydrochloric acid. Ammonia diffuses away into the atmosphere, leaving the strong acid behind, which burns the wood. The resulting chemical burn is identical to a heat burn in most respects.

This process sounds nastier than it is, in practice, and although prudence dictates erring on the side of caution and working with plenty of ventilation, the process does not produce a noticeable smell either of ammonia or of HCl. The only detectable odor is burning wood.

Steps

Step #1: Prepare stamp

For my simple "MAKE" stamp, I used these plastic-backed 1.5" foam-rubber letters from a hobby store.
Apply a strip of carpet tape to a suitably-sized piece of MDF, plywood, or other flat back. Remove the tape backing.
Arrange the letters as needed and push down the backing around each to fix it in place.

Conclusion

The "ink" described here is nothing more than an 80% saturated solution of ammonium chloride. Though it works well enough as described, there's plenty of room for improvement of its handling qualities. Adding egg whites or other thickener, for instance, might improve the handling qualities and/or reduce the tendency of the ink to diffuse along grain lines.

There is, moreover, no reason this material has to be applied with a stamp. It might also be applied with a stencil, a marker, a brush, a printer, or some other means, and each of these might have interesting applications and/or merit adjustments to the properties of the ink itself.

Other substrates might also be tested. Leather, perhaps?