You can call sodium carbonate by its nicknames: soda ash or washing soda or soda crystals or sal soda or even super washing soda! But don’t call sodium carbonate by its cousin’s name of sodium bicarbonate—aka baking soda. They are different compounds and the correct one for coloring wood is sodium carbonate.
Pardon the bad joke here, but besides being used as a clothes detergent, sodium carbonate has a laundry list of other seemingly unrelated uses. You might ask someone, “What do glass manufacturing, photo developing, pool cleaning and taxidermy all have in common?” and as they are walking away from you to find a more interesting person to talk to, you can yell at their back, “They all need sodium carbonate to get the job done!”
While you can find sodium carbonate as an ingredient in some laundry products, you’ll want to buy it in its purest form from a wood finishing supply company.
It is a white granular powder that is hygroscopic, which means it absorbs moisture from the air so you need to reseal the container immediately after you’ve extracted the amount you’ll need for your solution. The container must be airtight for the powder to maintain its potency. It is non-toxic and imparts more of a brown than a golden color.
Granted, sodium carbonate does not result in a particularly dramatic color change on wood. You may have to up the strength or simply use a different chemical if you want more visual “oomph!” So why would you want to use it? Why wouldn’t you just go straight to your clear coat finish? Well, sodium carbonate offers all the advantages of chemicals that aren’t achievable with just a plain, clear coat finish. Sodium carbonate patinates the wood and accentuates the grain pattern to a much more pronounced degree—look at that ripple on the maple sample!—and enables you to see deeper into the wood. And because sodium carbonate is non-toxic, you can worry a little less if the idea of working with chemicals makes you nervous. Best of all, you can dispose of the solution by dumping it right down the drain!
Recipe for Sodium Carbonate
1 tsp of sodium carbonate
3 oz. hot distilled water
3 oz. cold distilled water
Slowly stir one teaspoon of sodium carbonate into 3 ounces of hot distilled water. Mix until thoroughly dissolved and then add 3 ounces of cold distilled water. Mix thoroughly. Strain this solution into a clean container and apply when it has come to room temperature. Wipe the surface with a rag before the solution dries. Do not sand until after you have applied your first seal coat.
Alder
Cherry
Mahogany
Maple
Oak
Walnut
