# Thinning Rustoleum Ultimate Polyurethane for HVLP spray application



## paxorion (Oct 19, 2012)

I must be in the crowd that cries bollox when a top-coat finish says "DO NOT THIN", despite the manufacturer selling an aerosol spray can version.

I am hoping to come up with a more inexpensive water-based polyurethane (not looking to use lacquers) to thin and spray than any of the GF water-based products or Minwax Polycrylic. I've used Rustoleum Ultimate Polyurethane and have found it to be a great topcoat thus far. It appears to be water-based (milky white color, dries clear, water cleanup), and I plan on trying a batch to thin and spray in my HVLP but wanted to know if anyone else has come up with the same idea thus far. If so, I'd love to hear about the experience and if there are any things I should know/try before I get to it.


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## Hammerthumb (Dec 28, 2012)

I spray waterbased polyurethane but have never had to thin it. Never tried Rustoleum though. I would give it a shot without thinning.


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## OSU55 (Dec 14, 2012)

I spray waterborne polyurethane, target coatings EM 9000. I have thinned it with up to 10% water. I find the extender that target cells to be the best thing to use.it really does not need to be thinned. I believe general finishes cells and extender for their waterborne finishes as well. Any of them can be there in 5 to 10% with water.The best thing to do is get a Ford or zahns cup to determine Viscosity and then select the correct spray tip for your gun.


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## ScomelBasses (Dec 6, 2012)

I have sprayed the Varathane water poly for floors you can get at lowes. It has been great. I prefer GF's Enduro Var for the instruments I build because it has an oil-like amber effect but it's a lot more expensive. I've never thinned either product and use a Fuji Mini Mite 4.


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## Earlextech (Jan 13, 2011)

"DO NOT THIN" are lawyers words, not woodworkers. If you need to thin, up to 10%, to make the product work for you, then you do it. Because the manufacturer and the lawyers aren't there when your finish isn't laying out correctly!


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## hotbyte (Apr 3, 2010)

I recently sprayed some that Rustoleum product with great results and did not thin. I have the Earlex 5500 sprayer.


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## paxorion (Oct 19, 2012)

> "DO NOT THIN" are lawyers words, not woodworkers. If you need to thin, up to 10%, to make the product work for you, then you do it. Because the manufacturer and the lawyers aren t there when your finish isn t laying out correctly!
> 
> - Earlextech


Yep, I agree that its "our guarantees/promises are voided if you deviate from our instructions" language. Thanks.



> I recently sprayed some that Rustoleum product with great results and did not thin. I have the Earlex 5500 sprayer.
> 
> - hotbyte


Interesting, so when you sprayed Rustoleum Ultimate Polyurethane, did you have to thin it?


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## RRBOU (Feb 15, 2012)

> "DO NOT THIN" are lawyers words, not woodworkers. If you need to thin, up to 10%, to make the product work for you, then you do it. Because the manufacturer and the lawyers aren t there when your finish isn t laying out correctly!
> 
> - Earlextech
> 
> ...


I have sprayed it and did not thin it. I have sprayed gloss satin and mat. So far I really like it.


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## hotbyte (Apr 3, 2010)

> Interesting, so when you sprayed Rustoleum Ultimate Polyurethane, did you have to thin it?
> 
> - paxorion


Nope, I just poured through strainer. I'll try to check to be sure it was the "Ultimate" version.


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## wapakfred (Jul 29, 2011)

While I agree that "do not thin" is a CYA driven by the EPA and the companies lawyers, I only see that applying to solvent finishes. With a waterborne finish you can thin it too much and throw the chemistry out of balance, so with them I think it pays to follow the manufacturer's guidelines, most of them allow a little thinning…the 10% number seems to be a fairly common one.


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## hotbyte (Apr 3, 2010)

I checked can and it is the "Ultimate Polyurethane." I used the 1.5 tip with it.


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