In this fourth and final video, professional engraver and flintlock rifle maker Mark Thomas shows us his historical method for creating a strong contrast in figured wood (especially tiger maple) using Ferric Nitrate (also called “Aqua Fortis”) and a heat gun. If you missed his workshop tour, watch part 1 here.


This method involves using “Ferric Nitrate” which is a combination of Nitric Acid (be careful), water, and an old iron nail. Mark shares the “recipe” and safety precautions in the video, and here is another really helpful article on making and using Ferric Nitrate / Aqua Fortis. Note that every piece of wood is different and variations in the recipe’s ratios may need to be experimented with a bit to get your desired results. Just be careful!


A safer (and perhaps easier) method would be to just purchase already made Ferric Nitrate (search here and here and also here or call a chemical company near you). But if you really want to make your own Ferric Nitrate, here is one link to where you can purchase Nitric Acid (try searching here and also here) and here is a highly rated and affordable heat gun on Amazon. That’s all you need! Share your comments below and photos of your results over in our hand tool woodworking forum (here). Now a little more from Mark on purchasing Nitric Acid:

“Not sure of the strengths of nitric which is why folks may get different colors

[i.e. try experimenting]. Typically a 50% solution is the basis, 1:1 ratio, so 2 oz. of water to 2 oz. of nitric acid, (caution) always add acid to water NEVER water to acid. Then add your iron, large pieces will keep the chemical action less violent, steel wool and the like can cause a much hotter reaction. The chemical reaction will generate heat so the glass vessel must be able to withstand that heat. I would suggest purchasing a known acid stain like aqua regia or aqua fortis from suppliers, probably gun finishing sources.”


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