I saw an response that gave a formula of baking soda and water to treat your wood prior to burning, but lost the response. I know its a one-to-one ratio and use 1 tablespoon of baking soda, but do not remember how much water. Anyone remember how much water?
Hi Steve, it was 1 teaspoon to 3oz water.
However, I wouldn’t recommend it for Oak. I tried it on some scrap and was amazed at the colour change. Not really what you want. The Oak turned almost black - a really nasty colour. I guess because of the tannins in it. Some photos I took at the time. In the background is the untreated Oak, sitting on top are two pieces from the same plank. You can see what has happened. It’s the chemical equivalent of fuming! SO if that’s what you need then here is the solution:-)
You can pre-treat with all sorts of stuff, not just sodium bicarbonate.
Try a light wash of acrylic house paint. Dilute 1:1 with water, wipe on, wait 30 secs - 2 mins - try different times - and wipe off, let dry, light sand/wire wool, laser.
Table salt with teabags used to give any required colour is another. 15mg > 250ml.
It very much depends on the finish you want.
If you are just looking to get darker engraving, give it a wipe with thin shellac before engraving, then a wipe over with a cloth with thin dye after. The shellac will protect the unburned wood from the dye, and you can sand it off easily,
Some woods engrave really dark, some don’t. I wouldn’t get hung up on getting perfectly dark images from the laser, at the expense of a loss of detail or other changes. You can always mask and spray. And it’s truckloads faster, too.