Water-based Varnish on Top of Water-Soluble Dye Stain?
Regarding the title: Can I do it? I think I can. But help me with this; shouldn’t the water-based varnish re-dissolve the dye stain underneath and make a mess of it?
The reason I want to do this is because A) Never done it before, and B) It’s too cold to finish in the garage.
These water-based finish fumes are non-flammable, right? The water heater is right there. Of course I’ll have ventilation, fan, etc.
–Jonnieboy
Replies
Yes and no
Sure you can do it, but the water based varnish will redissolve the water based stain and may smear it, especially if you brush it. It would be less of an issue if it is sprayed. I would put down a barrier coat of shellac, dewaxed of course. To my knowledge, water based finishes don't emit any toxic or flamable/explosive fumes. What does the can say?
I find it interesting to read the Material Safety Data Sheets on the products and see all the specs, what can happen, what it contains, the flash points, etc...
Just Do It
jonnieboy,
It sounds like you've been looking in Jeff Jewitt's book for answers, but Bob Flexner spells out this particular topic more clearly.
Water-based finishes are 'coalescing,' as opposed to evaporative or reactive. but their drying characteristics resemble evaporative finishes.
Coalsecing finishes don't appreciably dissolve an undercoat, which also means they don't meld the coats together, so apply consecutive coats at about the same time, i.e. not weeks or months after one another.
Given all the above, and some deductive reasoning, it should be just fine to apply a water-based finish over a water-soluble dye stain. Don't use anything with polyurethane in the name or you'll have that gunky mess you're worried about.
There are fumes invlved in this process, but they aren't flammable.
You can do it, Jonnieboy. It'll be alright.
--jonnieboy
Thanks!
jonnieboy,
Thanks for the great info, but I didn't mean for you to go to all that trouble of researching. I will do it, jonnieboy. I will. I will go forward boldly.
Hey, you're a great guy. You've really helped me out over the months. Thanks for all that.
--jonnieboy
It's Nothing
Jonnieboy,
Aw shucks, Jonnieboy, it was nothing.
--Jonnieboy
No! Stop!
Jonnieboy,
Homestead Finishes' webite says the combination of water-based finish on water-based dye can muddy the dye. Use shellac for a topcoat instead.
--Jonnieboy
You don't want to get confused about waterborne finishes going over other waterborne finishes or stains--which doesn't have a technical problem. BUT it is not correct to say that a waterborne top coat applied over a water soluble dye won't dissolve the dye. Dye is different--it has no binder. You can redissolve the dye with water, including the water carrier in the waterborne topcoat at any time.
If you are spraying the topcoat, you can generally avoid problems by simply making your first coat or two relatively dry. But if you are brushing or rolling the action of applying the topcoat along with the water can definately lift the dye.
A coat of dewaxed shellac can be of great help here. For smallish objects this is a perfect place for the Zinsser aerosol shellac. It is dewaxed, even if that info is not on the can.
Good News
Steve,
Thanks for the response. That's great information and I will give it a whirl.
I don't think finishing is going to be like a light coming on. More like a Volkswagen Beetle getting up to speed. Just keep shifting through the gears and sooner or later I'll get there.
--Jonnieboy
Many times I've SPRAYED water based finish over water based dye and not had a mess. Spraying will not move the dye around. However, some of the dye will migrate into the finish. To minimize this, apply a thin coat of dewaxed alcohol shellac first. Target makes a water borne shellac which can be sprayed over water based dye, but my experience is that the dye will migrate into the water based shellac as well.
The only times the color migration has been a problem is when I had a substantial dust nib in the first or second coat over the dye, and sanded the nib too aggressively. Left a light spot because I sanded back more finish (and thus more migrated color) than in surrounding area.
I would expect, although I haven't done so, that brushing or wiping water borne finish over water based dye or even water based stain would move the color around, creating unevenness.
Consensus
Don,
It sounds like it's a consensus. I'm going to go with the shellac.
I'll check into the Target Waterborne Shellac.
--jonnieboy
Forget any water-based finish for fine furniture..
Life is too short. Forget about using ANY water-based finish of any type for fine furniture. They all stink - IMHO. And the amount of solvents vented into the atmosphere by solvent-based furniture finishes is miniscule compared to everything else. Use them without remorse.
Water-based is great for housepaint - little else.
Use scrap to test. Try stain (if you must - but why?) - then a shellac washcoat, followed by evaporative laquer - unless its a bathroom vanity/kitchen counter - then solvent varnish.
Just my 2 cents..
Chris
Ah Yes
Chris,
I read your, um, dislike, of water-based finishes in one of your posts. You know, I wouldn't even bother if I weren't afraid of the fumes from all the other stuff. Don't get me wrong, I like the environment and all, and the outdoors are nice once in a while. I just don't want to ka-blammo the house down if shellac or varnish fumes catch a spark from the water heater. Plus, I sort of want to see what the dye stains do.
Thanks for the response. I will keep your opinion in mind as I go forward.
--jonnieboy
The fumes from shellac are mostly just ethanol, with a bit of a few other nenaturing items added to make the solvent undrinkable (for tax reasons.) It also dissapates quickly. Not a concern, in my opinion, in the quantities that you would get from brushing or padding shellac on a few pieces of furniture, or even from the small amounts you get from limited aerosol application.
Waterborne products also have fumes that you don't want to breathe they just aren't as apparent. At least some of the glycol ethers, particularly ethylene glycol ethers have recogniced toxicity effects. (Antifreeze is ethylene glycol) Propalene glycol ethers are also used and appear to be less toxic. Compared to shellac I'd choose shellac everyday.
Wow, worried about fumes exploding a house? What concentration of fumes do you live with? I did a quick search of closed cup flash point for ethanol/air and think you would literally have to be be spraying 100% alcohol around to get a concentration high enough to explode from a spark. Think of a container with 100 alcohol saturation, no oxygen, will not explode. Conversely if you have 0% alcohol, nothing to burn. Yes, you can get get a fire if you ignite a liquid water/alcohol mixture but you will have to light it with a flame next to it.
Does some of this stuff stink? Yep. Spontaneously explode, naaa.
If I can only use waterborne finishes due to to the fire risk of spraying flammable finishes, how can shellack be suggested? I need a viable, non-flammable product.
We might need a time machine to get an answer...this thread is from 2010. Start a new one if you're looking for help with something!
The time machine is working!
Got me!! Sorry, senior moment s s s s,
They now make waterborne shellac, but I have not tried it.
Really? That's news to me
https://www.leevalley.com/en-ca/shop/tools/supplies/finishing/finishes/75696-emtech-water-based-shellac-sealer?item=56Z1910&gclid=Cj0KCQiAu62QBhC7ARIsALXijXRgjdHD1aZ7xfjK8Th-WuU3IPeVAfe-oSsEKrbPLG8zWUiw0EJf0I8aAo0wEALw_wcB
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