Spraying Dye on Maple

Another take on a common problem ó avoiding blotchy results when staining Maple. April 18, 2010

I have been using Transtint dyes for the past five years in my cabinet finishing.
My usual finishing schedule:
1. Sand wood to 150.
2. Mix Transtint per directions with distilled water.
3. Apply liberally on wood, with sponge, or rag, or foam brush. Thoroughly coat wood, to even out color as best I can.
4. Wipe off excess dye.
5. After dye is dry, spray on sealcoat cut 50% with alcohol.
6. Scuff sand with 220.
7. Apply gel stain.
8. After stain is dry, apply sealcoat.
9. Apply waterborne top coats.

Most of the time this method works very well. Right now, I am making samples for a project I am building of hard maple. The color to be is a golden to medium brown tone. I donít really like the way the samples are coming out, they are too blotchy after the dye goes on in my opinion, so I am looking for some help.

My questions are:
a. If I pre-wet the wood, with water before applying the dye, will that help? If so, how long do I wait to apply dye after wetting the wood?

b. If I spray the dye, can someone help me with technique on spraying the dye?

I have tried this a few times in the past, and I had a hard time trying to get an even pattern. I have read that guys recommend spraying several light coats, so how do you know when you have reached your final color? When flooding on the dye by hand, I can tell when the wood stops absorbing color, but with spraying I donít know how to tell, unless I spray it on heavy enough to have to wipe it off. I should mention that I donít have a spray booth, so I am limited to the water based dye. I also was wondering if with the dye the blotchiness is reduced by spray no wipe method? I appreciate any feedback!

Forum Responses
(Finishing Forum)
From contributor K:
You are probably going to receive dozens of different methods on this and most of them will work; you just have to find which one works for you. Here are my thoughts:

1. Maple is a splotchy wood, no matter how stain/dye is applied directly to the wood.

2. Dye stains are meant to be flooded on. By trying to spray it on lightly, you stand the chance of streaking and uneven color, depending on your spraying expertise. The larger the project, the more difficult it can be to achieve uniform results. If you want a lighter color, thin the stain. Others may prove me wrong, but I personally don't think that pre-wetting the wood will solve the splotch issue (some areas will still be wetter than others). Having said that, maybe it would act much as a wood pre-conditioner does.

3. Using a water-based finish over a water-based stain can cause bleeding. The rule of thumb is to not use the stain and finish that use the same type of solvent.

4. You can try using a lighter stain as your base color, then add tint to your finish to achieve your desired tone. Using this method, it is best to tint the thinned finish less, and control the color by the number of (thinned) coats. Then apply your regular topcoat. Caution, it is easy to add "just one more tint coat", then find out that the piece now is too dark.

5. Test, test, test. The technique that appears to be ok on a 12"x12" sample piece may not work as well on a large project.

5a. I think that I would sand maple to 220.

From contributor E:
As stated there is a lot of information on WOODWEB if you search the Knowledge Base. I use a dye stain in water for oak and sponge it on and wipe off. For maple it is a whole other process. I mix my dye with acetone and 5% water and spray it on in light coats allowing it to flash dry before the next coat. I use a SATA 3000 with a 1.3 tip. Then I use a shellac sealer or a very light coat of waterbased topcoat to seal. I say light coat because a heavy coat if not sealed will cause the dye to run as it re-dissolves in the topcoat. I can put on a mist coat of 100% of my topcoat twice to lock it down, lightly sand when dry and then 1 final normal topcoat to finish off.

When using a solvent like acetone, the solvent flashes off so quickly once it hits the wood that the dye does not have a chance to soak up into the open pore areas of the wood causing that blotching. If you want to use a gel stain after your seal coat go ahead.

This is one area where you have to practice on both solid wood and plywood as a veneer will take the dye different than the solid. I know that everyone in this forum helped me out a lot when I was in the same position as you right now. Practice and experimentation is key but I would limit the amount of water on maple and birch. I would go to a 180 or 220 before the dye. Pre-wetting isnít good, don't do it. I make a sample board and topcoat only half of it so you can see what the final color is as well as the dry stain color. Keep it beside you as you work. With acetone you can go back and tone your topcoat slightly if you are too light. Your spray pattern should be fairly high volume of air to finely atomize the dye. It should not be so low that you see large droplets (say 1-2mm is too large) it should look fine, not like drops.

From the original questioner:
Iím just wondering why sand to so fine a grit? Does it make for a more even color when applying the dye?

From contributor K:
Rule of thumb:
With open-grain woods, such as oak, you usually need to sand only to 150g. Softwoods, and tight-grained woods such as maple, 220g is considered better. This is mostly to do with the visibility of the sanding scratches after finishing.

Grit size is used by some as a color control - the finer the grit, the lighter the color for a given stain. This holds true more for pigmented stains than dyes. As the sanding scratches become smaller and finer, there is less area for the pigment to lodge in. Personally, I seldom rely on this method; since I almost always do toning after staining, that becomes my method of color-control.

One might ask, "If 220 is good, won't 400 (or 500, 600, etc) be better?" The answer is, "No." At some point you will start burnishing the wood - sort of creating a barrier against stain absorption and adhesion. Since the burnishing would be uneven, the resulting staining would be uneven, and the results would be un-satisfactory, and the customer would be unhappy.

From the original questioner:
I have always only sanded to 150 and it has seemed okay. Yesterday I did some more test samples at both 150 and 220, and applied dye to them. It looks like the difference was that the 220 board ended up a little lighter in color, and maybe a little more consistent, I suppose due to a finer scratch pattern?

From contributor S:
1. I would never sand maple past P150 the coatings have nothing to grab past that and peel off.

2. Water dye is useless on maple use spray NGR. You can still use the Transtint but you need an acetone/glycol ether solvent mix. 8 parts acetone, 1 part butyl cellosolve and 1 part glycol ether PM.

3. Spray using an HVLP gun at low pressure - 5 psi at the aircap which for most guns is 15-20 psi at the gun.

4. Spray in multiple light passes. Never have liquid dye sitting on the surface.

5. With this method maple can be stained as dark as you like with perfect uniformity.

From the original questioner:
Would you please explain why never to use water based dye on the maple? I have done it before, with what I thought to be pretty good success. I have heard of using the Transtint with a mix of solvents.

From contributor S:
Maple varies in density - thus the tendency to blotch. With an infinite supply of stain the more absorbent areas suck up more stain than the less absorbent. With spraying youíre not permitting this to happen if you do it right. You are depositing a flux of dye to the surface uniformly. With very fast evaporating solvents these flash off prior to soaking into the softer areas. The relative density of the substrate becomes a non-issue.

From contributor J:
Thanks for that formula I will have to try it. I have been using transtint in shellac. What advantages does your method have over shellac?

From contributor S:
Shellac is a resin. It forms a film. Pure solvents don't. You're making a toner and I'm making a stain.