Avoiding Grain Darkening with Stain on Red Oak
If you don't want the grain to darken, use a light touch with the spray gun. April 19, 2011
Question
We are new at finishing and interested in waterborne finishes only. We have red oak to finish and the customer doesn’t want the grain to darken, so I need to keep the grain from darkening. With waterborne what do I use for this? Do I fill the grain or dye?
Forum Responses
(Finishing Forum)
From contributor G:
Do you need to stain the oak as well? Darkening in the grain comes from dark components of the stain, black, brown, VDB, gilsonite, etc, which lodge there. No dark tints in the stain equals no darkening of grain.
From contributor S:
If you don't want the open grain in oak to get very dark, simply do not saturate your wood with stain. Spray on your stain lightly enough so that you can just get it to entirely penetrate as you wipe your stain-damp rag over the surface to remove excess stain. The wiping will even out the stain overall, without flooding the open grain. Do not spray any more stain than is the minimum to do this.
I do this all the time with oil base stain. It is the easiest type of stain to spray on, and also to spray and wipe a little extra on to a spot after you have done a whole surface and see a spot which is a little light due to lack of penetration. You can also use a spray only stain on oak to minimize grain contrast, but you have to be a pretty good hand at spraying to do this well.
From the original questioner:
Thanks for the reply. No dark pigments to lodge in the grain is the answer. The color is light/medium in the orange family. In waterborne what’s the chance I can successfully seal and then tint the top coats? Can I get enough color by tinting? If I just spray a stain and do not wipe it will that achieve not getting pigments lodged in the grain?
From the original questioner:
Contributor S - thanks for the reply. I know you say carefully wiping the stain off but would it work to just spray without wiping if the color is in the light to medium area? Doesn’t wiping just move the pigments into the grain? Does it make sense to spray and leave it to dry (without wiping off), by doing this will it negatively affect the application of the topcoats? I know oil based finishes work well but we have decided waterborne is the only finish we will use. We have limited space and do not have an expensive spray booth and the dangers of explosion with solvents are too great.
From contributor R:
Contributor S's advice is spot on and will probably yield you the best results. If you practice this spraying technique on a large sample of oak you will get a handle on the procedure before jumping into the job. It doesn't matter what type of spray gun you have since all of them have the ability to be adjusted to match your particular application. Fool around with the material knob until you find the sweet spot. Fool around with the fan adjustment until you find the best setting.
Experiment with the air pressure. If it’s too high you will blow the stain into the grain. Red oak has large deep open pores and it really takes a whole lot of liquid (stain) to seep into the pores.
