ut oh... Lacquer + Thinner= Coagulate?

[BradTheNailer]

Before I start, the finish looks great...but why did this happen?....

I have very little experience using lacquer, but I'm sure there is a simple explanation for this...

I went to mix lacquer thinner with the lacquer and as soon as the thinner hit the lacquer it coagulated.
I'm using American TH600 Alkyd Thinner F.D. and Watco clear lacquer semi gloss (brushable) lacquer.

I went ahead and stirred the cocktail up and it mixed together well and I sprayed everything (finish is looking great) but why did the lacquer coagulate the instant the thinner hit it?

Clean up as almost impossible. I ended up having to use mineral spirits cause the thinner was just turning the lacquer to gel when
I was trying to clean my gun.

WTF???




"you needn't troll the experts ..just come straight to the source" - Limey aka:Robert Bolton

[link:www.mgsawmill.com|M&G Sawmill]. Makers of the finest sawdust in Texas.
Oh, did I mention we have hardwood as well?

http://www.mgsawmill.com/images/flag.gif http://www.mgsawmill.com/images/texas.gif

[TDHofstetter]

Wait - isn't alkyd an enamel instead of a lacquer? What're the ingredients (check the warnings or the MSDS notes on the can)? Should be... like... acetone, toluol or toluene, xylol or xylene.

EDIT: Oops. Looks like TH600 is a mineral spirits type thinner, not a lacquer thinner: http://www.americancoatings.com/PDF/TH%20Series.pdf

-- Tim --

[stretch2187]

I think Tim's got you covered but for future reference it's probably not desirable to use brushing lacquer in a spraying application. Brushing lacquers usually have a retarder added so that they dry slower and flow out better off a brush. In hot, humid weather this might be desirable as it can prevent blushing, but in cooler weather it will contribute to slumps and runs on your vertical surfaces. At work we spray M.L. Campbell lacquer and it is excellent stuff, I've also sprayed lacquer from Sherwin Williams and it was also of good quality.

[BradTheNailer]

Tim,

First two words on the back label says "Contains: Xylene"

How the hell can you tell by looking at all that mumbo jumbo crap in that .PDF file that it's a mineral spirits???


Mark,

I've read that a brushable lacquer is ok to spray as long as you thin it when it's cooler.

Seeing how it's usually so damn hot and humid here, I was hoping I could thin in the cooler months so I could use it year around.



"you needn't troll the experts ..just come straight to the source" - Limey aka:Robert Bolton

[link:www.mgsawmill.com|M&G Sawmill]. Makers of the finest sawdust in Texas.
Oh, did I mention we have hardwood as well?

http://www.mgsawmill.com/images/flag.gif http://www.mgsawmill.com/images/texas.gif

[TDHofstetter]

It's the "aromatic hydrocarbon" (which usually refers to one of the less-volatile organic solvents), plus the flash point of 80 degrees compared with -4 degrees for acetone. The lower the flash point, generally, the "wilder" the solvent is, and the faster it evaporates. For lacquer, you want a very-fast-evaporating solvent with a low flash point. Lacquer is tough to thin.

The mineral spirits may WORK if you add heat (!!!caution!!!) to the process to "liven" the solvent... but it's best just to start out with a solvent specifically formulated for lacquer in the first place.

-- Tim --

[BradTheNailer]

So should I just buy some acetone to thin it with?



"you needn't troll the experts ..just come straight to the source" - Limey aka:Robert Bolton

[link:www.mgsawmill.com|M&G Sawmill]. Makers of the finest sawdust in Texas.
Oh, did I mention we have hardwood as well?

http://www.mgsawmill.com/images/flag.gif http://www.mgsawmill.com/images/texas.gif

[TDHofstetter]

That'll usually work fairly well. The coatings companies (like American Coatings, for example) do spend the time to come up with idealized blends of several "hot" solvents to sell as lacquer thinner, shooting for a middle ground in solvent characteristics - like evaporation time that works well for lacquer spraying, completeness of solvency, etc etc. The factory-blended lacquer thinners (labeled specifically as such) are really pretty good.

That's an area I'm not ready to go into yet; I blend my own waxes and Danish oils and such, but I'm still pretty happy to buy someone else's blended lacquer thinner.

-- Tim --

[stretch2187]

Yeah, it's probably fine to spray brushable lacquer, I just prefer to add my own retarder if I need to. FWIW, we mostly spray thinned lacquer year round the only exception being the final coat of full strength lacquer. However, we're moving toward not spraying a full strength final coat. As far as lacquer thinner goes, we use the crown brand that's available at Lowes.

[BradTheNailer]

Thanks for all the help.

How I didn't mess things up is short of a miracle. I'm headed to Lowe's now for some thinner. Crown is what I use for everything else, I used the American brand because it was FREE.

Another lessoned learned...Free isn't always good.


Edit in: After returning from Lowe's, I was reminded why I jumped on the free thinner so quickly.... Crown Lacquer Thinner: $14.00 gal.



"you needn't troll the experts ..just come straight to the source" - Limey aka:Robert Bolton

[link:www.mgsawmill.com|M&G Sawmill]. Makers of the finest sawdust in Texas.
Oh, did I mention we have hardwood as well?

http://www.mgsawmill.com/images/flag.gif http://www.mgsawmill.com/images/texas.gif

[rrich]

Fourteen bucks ain't bad.

[Gabe Livingston]

You should check with an automotive paint supply store, I got 5 gal. of laquer thinner for about $20. I'm almost through half of it and it seems to be working great, I use S.W. laquer to spray, spraying 20 cypress doors right now.
Gabe