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waterbourne finish ???

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Forum topic by Howie posted 657 days ago 520 views 0 times favorited 9 replies Add to Favorites Watch
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Howie

2656 posts in 1559 days


657 days ago

Does the waterbourne varnish 2nd coat “melt into” the first coat like the oil based poly?

-- Life is good.


9 replies so far

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Cosmicsniper

2199 posts in 1795 days


#1 posted 657 days ago

No…and neither does oil-based poly.

-- jay, www.allaboutastro.com

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Joe Lyddon

7689 posts in 2689 days


#2 posted 656 days ago

Cosmicsniper +2

A light sanding between coats… is required.

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

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a1Jim

112027 posts in 2214 days


#3 posted 656 days ago

Yes and no . Water base with allow a second,third,etc as long as it;s done in the open time the manufacturer states.
After drying beyond that it will still cling to a previous coat but not anywhere nearly as well.

-- http://artisticwoodstudio.com Custom furniture

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live4ever

983 posts in 1646 days


#4 posted 656 days ago

It will if you are applying the second coat within a certain amount of time (sometimes called “burn-in time”). For the WB finishes I use it’s around 24 hours. After the first coat cures, then no, and you’d need to scuff-sand like Joe said to get good adhesion between coats.

-- Optimists are usually disappointed. Pessimists are either right or pleasantly surprised. I tend to be a disappointed pessimist.

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shampeon

1359 posts in 820 days


#5 posted 656 days ago

Target Coatings EM6000 does in fact melt into the previous layer. Poly doesn’t, but nitrocellulose lacquer does.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

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live4ever

983 posts in 1646 days


#6 posted 656 days ago

A bit of clarification on EM6000. It’s advertised as having infinite burn-in time but in reality even Target Coatings recommends a little scuff sand if it’s over 24h for best results.

-- Optimists are usually disappointed. Pessimists are either right or pleasantly surprised. I tend to be a disappointed pessimist.

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Cosmicsniper

2199 posts in 1795 days


#7 posted 656 days ago

Howie: The confusing part of your question is the words “melt into”. That is more descriptive of evaporative finishes like shellac and lacquer, both of which react with its solvent once reintroduced to it. Put down a coat of lacquer, let it dry, and the solvent in the next coat will reactivate the first layer and they’ll melt together.

Varnishes, like poly, do not act this way. They are “reactive finishes,” meaning that they change through chemical reaction while drying. During this “curing,” once the solvent is dried off, they can no longer be reactivated by the solvent in subsequent coats. So they harden in layers relying on a mechanical adhesion to each other. Thus, you give it “some teeth” by scuff sanding between layers.

-- jay, www.allaboutastro.com

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Cosmicsniper

2199 posts in 1795 days


#8 posted 656 days ago

Hmm, okay, in an attempt to be clear about certain things, I’ve learned something myself. Water-borne finishes apparently do burn-into a previous coats by reactivation with its solvent, in that case glycol ether. I had recklessly categorized them as varnishes. This is again an example where product-labeling is deceptive…they are often called “varnish,” “poly,” and even “lacquer.” In truth, they are acrylics, with some resins blended in for hardness.

However, part of what I said is correct in that by comparison to true evaporative finishes, they have a smaller percentage of solvent, so there isn’t as much of a “melting into” with the water-borne stuff. Chiefly, it means that you don’t need a mechanical “tooth” to adhere coats, so no sanding. This probably explains why I haven’t noticed this in action so much when I spray such finishes. I usually handle them like shellac or lacquer without sanding in between. Now I know why I like them so much.

Thanks for sparking the educational opportunity!

Nevertheless, the original post does contain an error…oil-based poly most certainly does NOT “melt in.”

-- jay, www.allaboutastro.com

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Howie

2656 posts in 1559 days


#9 posted 656 days ago

Thanks to all for the clarifications. As usual ,I can always find an answer at LJ’s.
I used to use the poly but am starting to use the waterbourne. I figure I might as well get used to it, won’t be long til that’s about all you get.

-- Life is good.

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