Blush
- Thread starter dmraco
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Cagey
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No, it won't fade away. And no, you can't sand it off without removing that whole layer. But, removing that whole layer is probably not as tough as you might imagine. It's not like you have to strip it, you just have to sand it back, and it's thin. Not the end of the world, just a waste of finish. But, you need a lotta coats anyway, so no sweat.
You have to watch the temperature and humidity when spraying lacquer. It's more sensitive to such things than just about any other finish you can apply. It's well worth the money to buy a thermo-hygrometer so you don't shoot unless conditions are right. Something like this...
... is invaluable. You don't have to buy that one; there are a million of them out there for between $10 and $20. Technology has made them easy, accurate and cheap. Don't trust the weather forecasts - those guys are about useless unless they're predicting a hole in their heads at the same time they're being shot at. Even then, they'll probably be wrong. You need to know what it's like right where you're at.
Then, keep in mind the "Rule of 65" which says "Never shoot lacquer at temperatures below 65°F, or above 65% humidity." And those are extremes. Ideally, you want it warmer and drier than that, but not too much warmer. A perfect day in my mind would be 75°F and 40% humidity, but we can't all live in Puerto Rico. So. wait for warm weather and learn to love retarder, which slows down the solvent's boil-off.
You have to watch the temperature and humidity when spraying lacquer. It's more sensitive to such things than just about any other finish you can apply. It's well worth the money to buy a thermo-hygrometer so you don't shoot unless conditions are right. Something like this...
... is invaluable. You don't have to buy that one; there are a million of them out there for between $10 and $20. Technology has made them easy, accurate and cheap. Don't trust the weather forecasts - those guys are about useless unless they're predicting a hole in their heads at the same time they're being shot at. Even then, they'll probably be wrong. You need to know what it's like right where you're at.
Then, keep in mind the "Rule of 65" which says "Never shoot lacquer at temperatures below 65°F, or above 65% humidity." And those are extremes. Ideally, you want it warmer and drier than that, but not too much warmer. A perfect day in my mind would be 75°F and 40% humidity, but we can't all live in Puerto Rico. So. wait for warm weather and learn to love retarder, which slows down the solvent's boil-off.
Tonar8352
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Do a flow coat with a heavily thinned coat of finish. I would mix one part finish with a 50/50 blend of thinner and retarder. That will re-melt the surface and allow the moisture to escape. You may have to let it set a little longer before you do the final sanding because the retarder will cause to cure slower.
dmraco
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I will try sanding. It was only one or two passes of lacquer. It had faded about 50% overnight but I think what is there is here to stay. It will go away with just a slight rub of my fingernail.
Question...how long should I let it cure? 24-48 hours??
Interesting on the retarder. I have NEVER used it. I only use lacquer and thinner, varying the ratio depending on where I am in the process. Maybe because I usually spray with higher humidity levels I have never needed it.
I knew I could count on you two for good advice.
Question...how long should I let it cure? 24-48 hours??
Interesting on the retarder. I have NEVER used it. I only use lacquer and thinner, varying the ratio depending on where I am in the process. Maybe because I usually spray with higher humidity levels I have never needed it.
I knew I could count on you two for good advice.
Cagey
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If it's warm/humid enough that you're getting blush, it was ready to sand yesterday. You only need to let it cure for a long time when you're going to get down to fine sanding and buffing, where you need the finish to be as hard as it can get. That usually takes about 2 weeks.
Retarder is your friend. Acetone (lacquer thinner) only has a boiling point of about 135°F, so it evaporates pretty damn fast at human-comfortable ambient temperatures. That's where the "blush" comes from. If it's too humid or too hot in your painting area, the pressure change as the lacquer leaves the spray gun causes moisture to condense in the spray stream, then the higher heat causes the surface of the lacquer to dry too fast, which traps the moisture in the finish. That's the milky effect you see.
Retarder is a mixture of different solvents that slows down the evaporation process, so the moisture has a chance to escape before the surface of the finish skins over. Also, since the lacquer isn't drying so fast, it has a chance to "flow out", so you get a flatter surface. You just have to be careful how much you use because if you go to far, it gets real easy to develop sags and runs, and getting rid of those is no fun at all. Typically, you use about 5%-10% retarder, depending on ambient conditions.
If it was me, I'd be trying Tonar's suggestion before I started sanding on the thing. He's probably forgotten more about finishing than I'll ever know. I suspect you'll get more reliable results with his method, and save yourself some work. They should sell retarder at the same place you bought the lacquer and thinner.
Retarder is your friend. Acetone (lacquer thinner) only has a boiling point of about 135°F, so it evaporates pretty damn fast at human-comfortable ambient temperatures. That's where the "blush" comes from. If it's too humid or too hot in your painting area, the pressure change as the lacquer leaves the spray gun causes moisture to condense in the spray stream, then the higher heat causes the surface of the lacquer to dry too fast, which traps the moisture in the finish. That's the milky effect you see.
Retarder is a mixture of different solvents that slows down the evaporation process, so the moisture has a chance to escape before the surface of the finish skins over. Also, since the lacquer isn't drying so fast, it has a chance to "flow out", so you get a flatter surface. You just have to be careful how much you use because if you go to far, it gets real easy to develop sags and runs, and getting rid of those is no fun at all. Typically, you use about 5%-10% retarder, depending on ambient conditions.
If it was me, I'd be trying Tonar's suggestion before I started sanding on the thing. He's probably forgotten more about finishing than I'll ever know. I suspect you'll get more reliable results with his method, and save yourself some work. They should sell retarder at the same place you bought the lacquer and thinner.
Cagey
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I hate sanding, too. It's work, which means it's no fun. Plus, it's the fastest way to screw up a finish.
As for getting retarder, you may want to try the furniture refinisher's shops. If they don't sell the stuff, they'll know where to get it. Used to be the automotive finishing shops were a reliable source, but so few car guys use lacquer anymore they're not as good a resource. I don't think there's anything in it that might be banned if they're allowing acetone sales, but you never know. There's toluene, a couple types of xylene and some benzene in it, all of which are known cancer agents, so if you're in California you may have some trouble. Hell, I just read that Massachusetts passed a law to put nail polish remover behind the counter now because it's mostly acetone, which is a precursor necessary to make methamphetamine. Dummies. You can buy the stuff pure by the gallon at any hardware; I hardly think the cookers are buying 2 ounce bottles of the diluted/oiled/perfumed/overpriced version from Maybelline. But, that's politicians for you. No need to understand what they're doing, they just do what the campaign fund suppliers order them to.
As for getting retarder, you may want to try the furniture refinisher's shops. If they don't sell the stuff, they'll know where to get it. Used to be the automotive finishing shops were a reliable source, but so few car guys use lacquer anymore they're not as good a resource. I don't think there's anything in it that might be banned if they're allowing acetone sales, but you never know. There's toluene, a couple types of xylene and some benzene in it, all of which are known cancer agents, so if you're in California you may have some trouble. Hell, I just read that Massachusetts passed a law to put nail polish remover behind the counter now because it's mostly acetone, which is a precursor necessary to make methamphetamine. Dummies. You can buy the stuff pure by the gallon at any hardware; I hardly think the cookers are buying 2 ounce bottles of the diluted/oiled/perfumed/overpriced version from Maybelline. But, that's politicians for you. No need to understand what they're doing, they just do what the campaign fund suppliers order them to.
Tonar8352
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I never spray any finish with out some retarder mixed in. It definitely improves flow and leveling of the finish and I have shot lacquer when it was so foggy out you could not see across the street and never have had any blushing issues.
Back in the good ole days before they started messing with the VOC of finishes painters would just do a fog coat of lacquer thinner over the blushed surface to open up the finish and let the moisture escape.
I see no need to sand the surface, that will not let any of the moisture out unless you go all the way to the wood. Trust me grasshopper :laughing7: do a flow coat. If that does not take care of it then start sanding
Back in the good ole days before they started messing with the VOC of finishes painters would just do a fog coat of lacquer thinner over the blushed surface to open up the finish and let the moisture escape.
I see no need to sand the surface, that will not let any of the moisture out unless you go all the way to the wood. Trust me grasshopper :laughing7: do a flow coat. If that does not take care of it then start sanding
Cagey
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Tonar8353 said:
Back when I first started using lacquer, toward the end of a day I put a coat of clear on that was a bit uneven, but didn't feel like mixing up another batch that day to try and fix it. So, while I was shooting pure acetone through the gun to clean all its internal nooks and crannies, I thought "why not shoot this wasted thinner at the body? It'll melt it out smooth, and I'll have a better starting point tomorrow!" Stupid me. Shot that body until it was wet, and then watched in horror as the finish curled up and went straight to hell. It was like watching some Hollywood time-lapse special effect where you wanted to show somebody ageing from teenager to rotting corpse in two minutes flat. Absolutely ruined the thing <grin>
Cagey
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It varies, depending on where you are in the process.
You might want to read this tutorial. It's about the best treatment I've found on the subject. It's written in what amounts to three stages - overview, general procedure, detailed procedure. It's long, but read the whole thing. It's something of a self-serving piece in that they specify the products they sell, but you don't have to use them; everybody sells the same things from different manufacturers. The procedure is solid, though, and is guaranteed to return good results.
You might want to read this tutorial. It's about the best treatment I've found on the subject. It's written in what amounts to three stages - overview, general procedure, detailed procedure. It's long, but read the whole thing. It's something of a self-serving piece in that they specify the products they sell, but you don't have to use them; everybody sells the same things from different manufacturers. The procedure is solid, though, and is guaranteed to return good results.
