Dyeing Wood for Colored Segments

[Brent Dalrymple]

I have a bowl designed that will use some colored segments. I couldn't find much information on the internet on dyeing wood (only veneer, but that's thin stuff) so I thought I'd do some experimenting. I bought a 1 gallon vacuum chamber and single-stage vacuum pump. In addition I bought an acrylic tray that is 2"x4"x8" and made a cover for it out of 1/16" acrylic (see photo). I also cut some pieces of 10-24 threaded rod to act as spacers and weights. I put a couple of hard maple strips, 3/16"x1"x7-1/4", into the tray using three spacers to hold them off of the bottom of the tray and 3 spacers as weights on top. I then added enough water-soluble aniline dye to cover the wood, put the top on the tray to keep splashing to a minimum, and put the tray in the chamber. This little chamber and pump will get to -29.5mm Hg in about a minute, but at that pressure water boils at room temperature, so I stopped pumping at 27mm Hg. Initially I could see a lot of bubbles caused by the air being evacuated from the wood. I let the strips sit under vacuum for about an hour, which may be longer than necessary, and then brought the chamber up to atmospheric pressure. I dried the wood strips and then cut them apart in several places to find that the dye had penetrated entirely through the wood strips. So, it looks like this is going to work--I can mill the maple strips, dye them, sand off the raised grain, and then cut my 1/8"-thick segments. In the photo below there are only two wood strips so you can see how the spacers are used, but the tray will easily hold 12 strips with spacers, so I can do about 7 ft. of 1/8"x1"x7" maple in one run.

 

[stuart johnson]

Interesting, as long as you are testing try running several thicknesses to see just how thick you can get the dye to penetrate. A deep red, blue or green would be great.

 

[Bob Beaupre]

Brent, very interesting experimenting. What did you for the dye. Was it water based or alcohol base?

 

[Brent Dalrymple]

Interesting, as long as you are testing try running several thicknesses to see just how thick you can get the dye to penetrate. A deep red, blue or green would be great.

I'll be away this week, but I'll try your suggestion when I get back and post the results. It looked to me like most of the bubbles came out of the ends, so I suspect that most of the dye gets in that way too. If that is the case, thickness may not matter as much as length.

 

[Brent Dalrymple]

Brent, very interesting experimenting. What did you for the dye. Was it water based or alcohol base?

I used water-based aniline dye (Moser's). Alcohol might be difficult for a couple of reasons. First methyl (and other forms of alcohol) have lower boiling temperatures at 1 atmosphere than water so I suspect (I haven't looked it up) they would boil at a higher pressure than water, which means that you couldn't pull as much vacuum to get the air out of the wood as you can with water. Second, and most important, the alcohol vapors would contaminate the oil and really screw up the vacuum pump unless you used a LN2 trap to catch the vapors. Finally, water-soluble aniline dyes are more color-fast than alcohol-soluble aniline dyes, or so I've read.

 

[mfisher]

Interesting method. Could you post some photos of before / after of the dyed wood? Seeing some cross section would be great.

 

[Brent Dalrymple]

Interesting method. Could you post some photos of before / after of the dyed wood? Seeing some cross section would be great.

I'll do that after I do some experiments with different thicknesses of wood next week. For 3/16" thick maple, however, it was uniform color all the way through using a dark magenta dye.