Switching to Waterborne Finishes
Thoughts on practical application techniques and continued health precautions for a finisher who's going water-based. January 14, 2008
Question
I have recently switched over to waterbased stain to make my transition to being completely WB. Lacquer and all. When I was using NC lacquer, I used to seal the wood lightly and sand before staining. Does this also apply to waterbased? Can I seal with Target's sealer and then stain with a waterbased stain? If so, how much would I have to dilute the product? The kitchen I am working on is maple and all products are from Target except the stain, but all is waterbased.
Forum Responses
(Finishing Forum)
From contributor P:
What brand of WB stain are you using?
From contributor A:
Water-based stains blotch just as badly as solvent-based stains, and are prone to the same uneven staining characteristics on ply versus solid wood and end grain as are solvent-based stains. Whether using solvent or water-based stains, if you use a spray only (no wipe) stain, you will have less chance of blotching. Using a washcoat of shellac (about 1 lb. cut) or reduced sealer (5 - 10% solids) will greatly reduce blotching and uneven staining on end grain, ply, and solid wood. Use of a washcoat will somewhat reduce the intensity (deepness) of any applied stain. Although I have not used it, other folks tell me that Target's WB shellac works well in this application.
Personally, I've tried WB stains, and I've gone back, for now, to using solvent based stains and dyes under both WB and solvent-based topcoats. I find they're easier to use, and I can get more consistent results. I've had good luck with the Mohawk line.
From contributor W:
Pre-stain sealing with WB stains is still required if you want a blotch-free color effect.
From the original questioner:
I usually take care of the blotchiness by shading, and it works out very well. It is just that with the amount of work I have coming in, there is no time to sand the doors, so I need a way to get a uniform finish without sanding and very little shading, because they both take a lot of time. I would also like a check for a million dollars. ;)
But seriously, if anyone out there does industrial finishing, they'll know what I am talking about. I sprayed for a door manufacturer and when the doors were finished, I used to spray them with NGR, sealer, toner, and then finally three coats of lacquer. I need to find a way to do this with water based products.
From contributor P:
Not sure how you can skip the sanding, since the WB stain will raise the grain. I use WB dyes instead of stain when possible. Usually no blotching.
From contributor W:
Try your standard NGR stain, then seal/tone and topcoat with the Target WBs until you get your stain issue ironed out. At least you will have 75% of your process transferred over to a water-based system. The Target WBs will be compatible over an alcohol dye and the grain raise will be minimal at best. Did you try their Ultima-WR stains? Minimal grain rise but it will take into a 100% WB process.
From contributor G:
Pre-raise the grain with water in a spray bottle.
From contributor I:
How about Sherwin-Williams Universal dyes in water, sprayed on like your NGR?
From the original questioner:
Although WB does raise the grain, I find that on species like maple it is not a problem after it is sealed. Oak would be a very different story. My goal is to switch to waterborne 100%, so I guess some experimentation will be in order. I have been in this business for a while and I see many old timers retiring who are very sick due to the effects of certain chemical products. For this project, though, I will try Waterman's suggestion.
From contributor A:
Please don't assume that because you're spraying waterborne (WB) finishes that you're completely safe. There are fewer hazardous solvents in WB finishing systems, but there are still some there. You should always use a respirator when spray finishing (including stains, dyes, sealers, etc.). Many of the old timers you're referring to are (were) only 45 - 50 years old. In the auto body painting field, they used to say you never see any old painters. Most of these guys never, or only sporadically, used respirators, or used ones with spent cartridges. The biggest advantage WB systems have over solvent-based systems from a safety standpoint is relative lack of flammability. From an environmental standpoint, they're greener.
Many folks who wear respirators have never been fit tested; they just pick up a respirator they think fits, and wear it. Although better than not wearing anything, a respirator that doesn't fit properly will still let lots of vapors and particles through. Check with your safety equipment supplier about fit testing.
From contributor N:
I have had excellent results with the ICA CNA waterbased stains. Another thing to do is to tint your sealer with the stain and cut it way back to use as a sealer/toner and stain over top of that. You can also tint the sealer with the stain and not reduce it and build the color in stages until you get what you are looking for.
From contributor M:
I mainly use waterborne RKR finishes on maple. Spray stains only for maple. I have done numerous jobs with a very dark espresso color and have no problem with blotching of color. If you aren't sure about your spray technique, mix a 50/50 ratio with the clear spray stain base and build in layers.
