Question
I am trying to deal with softwoods and woods that tend to blotch when stained.
So far, my best method is to dye the wood before a wash coat. What type of base should I use with the dye - water or oil? I am guessing that when using a water based dye, it would be best to pre-wet and sand the wood before dying. Next, the wash coat (I'm assuming sanding sealer here) - there are lacquer sanding sealers and varnish sanding sealers. Does it matter which one I use with an oil based stain (after the wash coat) and then the final finish?
I'm in the middle of a cabinet using p. mahogany (by mistake), and would like to use it up before never touching the stuff again.
Forum Responses
(Finishing Forum)
From contributor B:
Water soluble dye is the most colorfast. And yes, you should do a grain raising procedure prior to application. If you use water soluble dye you can go right with oil base finishes without a sealer. A sealer is necessary when using a waterborne finish with a water soluble dye; it activates the dye.
You will notice that many companies offer dyes that make about a quart of stain per dry ounce of dye, but this typically indicates that the dyestuff has been cut or is of a lower quality. Aim for products that indicate that 1 oz = 1 gallon of stain.
Russ Ramirez, forum technical advisor
Pre-conditioners, sealer coats and glue sizing may all work when applied properly, but not too many shops want to use these mediums on every piece they finish, and as I said, you can only see the blotching after it's stained. So it becomes "should I or shouldn't I?".
This is one of the biggest reasons for doing factory finishes using toners - you never have to worry about blotching. To get true transparent finishes, a little blotching isn't that bad after all. It's natural - it's in the wood!
I never favored the idea of toners or shading due to the scratch and nick repair complication. I also favor the idea of transparent finishes.
The big difference in spraying the water and alcohol stains is that the alcohol stains dry much faster and do not raise the wood grains.
You're not the only one who doesn't like toners - they are not for everyone. They certainly have their place in finishing, just like the pigmented stains. It depends on the type of finishing you're doing.
"Dyes are microscopic and are absorbed evenly in hard and soft portions of the grain and don't result in blotching."
That just is not the case. Dyes are microscopic but they do not absorb evenly into hard and soft woods. Neither do they eliminate blotching. In fact, they can intensify blotching! The wood itself (and wood species to some degree) is the culprit and will determine to what degree blotching is a problem. Along the face of the board, how the fiber orientation presents itself at the surface of the board (where the stain is applied) is *the* determining factor of whether or not the surface will display severe, minor, or no splotching at all. Different wood species are known to be more or less problematic as far as this is concerned. For that matter, it is not so important whether the stain is a dye or pigment, or a combination of the two - as most ready made (hardware store type) stains happen to be.
I don't know what Mr. A had to say exactly, but could it be that you have misinterpreted him? I expect that he is well qualified (better than I) to know that what you have written is not completely accurate.
To illustrate my point, take any light colored, hard or soft wood, sand it thoroughly, and apply whatever (preferably dark) stain that you desire, saturating all surfaces of the wood completely with the stain. Look at the end grain on that board and you will see a drastic difference between the color intensity between it and the face of the same board. Why is this?
It would be nice if all trees started out on flat and level ground and grew perfectly straight to the heavens, with no branches reaching out away from their trunks. Nice too if the sawyers in the mills could follow precisely along the length of the wood fibers, severing through none, as they produced one perfect and consistently surfaced textured board after another. But this is obviously not possible and I think not even desirable, because there are not many objects in this world that are more beautiful than a well figured, beautifully finished natural wood product.
What Mr. A may have said or wrote was that his new dyes are more colorfast in comparison to the older aniline dyes.
If the dye stain is shot from a spray gun (as I prefer to do) then it is much easier to control and minimize splotching by making very light passes, directing more or less stain over certain areas of the surface to help even out the color contrast across the entire surface being stained. This is less easy to do by hand application with dye stain alone, as a full saturating coat is most often required in order not to leave “dry” spots, or areas across the surface.
I have a simple, highly consistent solution for splotch prone woods that I use, and it is reasonably priced and available nationwide - but I ain't gonna tell you what it is 'cause you'll just make fun of me... Hint: I believe you once gave me the formula to make the concoction myself.
As a personal preference, I believe that light-colored dewaxed shellac like the Zinsser SealCoat product or a wash coat of lacquer is the way to go in terms of its value added to the appearance of the work.
Russ Ramirez, forum technical advisor
Also, what does everyone recommend - water based dye or alcohol based bye?
My plan so far is to spray dye, washcoat, and if I can't get the grain I want, washcoat, then wipe on some pigment stain. Then cover the whole thing with poly. Can anyone better this plan? Again, I'm using p. mahogany and am trying to doctor it up to make it look as close to the real stuff as possible (before I never touch the stuff again).
Russ Ramirez, forum technical advisor
Let's go with first principals. The idea is to harden the soft parts of the wood, which are those that will splotch. Glue-size being waterborne deeply penetrates this softwood and reduces its absorption of stain. Since the stain is not able to resolvate the glue-size (solvents will not dissolve it, only water does), blotching is thereby prevented. This mixing of solvent systems is a key to effective barrier coats, which is what you're really trying to accomplish here. Shellac is the all-time best example of this concept when used as a sealer. Nothing attacks it except alcohol, so waterborne and solvent borne go on top of it without dissolving it. Chemistry is a thing of beauty.
And yes, contributor D, I do remember providing you with Chris Minick's pre-stain conditioner formula. In that case the key is saturation, which is why you need to come back with the stain before the pre-conditioner dries. You use his conditioner to load up the pores of the wood so that the stain can't be overly absorbed. Different idea that also works.
Russ Ramirez, forum technical advisor
Lightfastness is determined by the chemistry of the dye, not what it dissolves in, and there are plenty of water soluble dyes that have no lightfastness whatever.
As for using water dyes to control splotching, it's just one of the many methods you can use, but you can get splotching with water dyes, as with any colorant. In a general sense, water dyes tend to de-emphasize grain. In a commercial, production setting, washcoating is certainly about the most foolproof.
I think in many ways a balance needs to be struck between eliminating color variance and good finishes that reflect depth and interest. You can get to a point in eliminating splotching where the wood looks like Formica.
The problem is that Ethan Allen and everybody else that makes production furniture has used multi-step finishes to reduce wood to a uniform commodity like laminate.
Speaking of laminate, I just finished a modern table for a co-worker that required that I buy some black wood grain laminate from Wilsonart that has a perfect oak wood grain texture to it. They call this finish cathedral and it was perfect in every way. It was also plastic and not wood, so we need to ask "Where do we stop?"
Comment from contributor M:
I often use a light spit coat of clear or amber shellac - mix one part shellac to about four parts denatured alcohol. Put this on the piece, let dry and then stain over. The open or more porous grain will take the shellac and the stain will go on evenly. Also use this method to treat end grain - but you might have to do it twice (on the end grain only). If the wood has an open texture (porous) then you will still need to fill the grain with paste filler or whatever you prefer as the shellac won't be enough of a base when applied this thinly.
