Epoxy primer blushing

O

old soul

Member
Been using the SPI black epoxy primer for many years now. This is the first time I have ever had a blushing problem.
First let me say this is NOT a problem with the product but with the process, meaning what I am doing.

For the last 3 weeks every time I prime a large panel it will blush. No consistency, just in random spots. Sometimes
it is the size of a football and other times it will be a stripe from one end to the other (hood).

The weather here in North Carolina has been VERY rainy and VERY humid. The humidity has been 95-98% in the mornings,
low to mid 90% all day. Temperature about 77-89. Today it didn't get below 90 percent humidity until after 8 pm. That is when the bugs start
coming out so I cant really wait until then.

The parts that were primed to be painted over are not a problem but the inner fenders, and underside
of the hood were going to be left in epoxy primer. They will have to be done again. ( = lost time and materials)

Using a DeVilbiss FL3 with a 1.5 with the epoxy reduced about 10%. Doesn't matter if I spray morning, noon or evening.
What can I do to prevent this from happening ? Thanks
 
Retarder comes to mind, but my humid painting skills are a bit rusty, so let's hear from the rest of the gang.
 
I did talk to Barry the first time it happened but we did not discuss preventive measures. Also, at this time I am using PPG DT895 reducer.
 
I live in south Carolina and the humidity is high too. I haven't had any blushing issues with epoxy but I don't normally reduce it. I have had that problem with oil base paint thinned with mineral spirits in high humidity especially on wood so maybe reducer speed or spraying a little thicker than normal? I spray epoxy with a devilbiss starting line gun with a 1.3 tip about 25 to 30 psi trigger pulled. Sometimes when the planets line up just right nothing works.
 
here in jersey the humidity is absolutely terrible 90-98% for the past few weeks. just the way it is this time of year. a couple things to try...... spray thinner wet coats with alot more flash time between. wait 1/2 hr between coats. whats goin on is the panel is getting cold due to the solvents flashing too fast and the humidity condenses in the paint film. slow that whole process down with thinner coats and slower solvents.
 
82...is addition to the explanation above, blushing is when the paint gets a milky look to it
 
No shine that was before me, on cars anyway. Wood is another story. Some years back i had blushing issues but no more. Just tweaked my methods here and the problem seemed to disappear
 
man we fought it for years. sometimes we would be shooting so hot with retarder we would melt stripes. shooting a whole car in lacquer was pure pia . there were days when we just had to give it up and go home.
 
Thanks for the replies, guys. I don't have any retarder yet but will do as Jim says: thinner wet coats. I was already giving it a 2 hour flash.
Maybe shoot it straight (no reducer) to have one less solvent in the mix. Would that make any difference?
 
I've never used DT895 in epoxy. There could be something about it that is making your problem worse, who knows. Maybe it has even absorbed moisture from the air?

Unreduced might be something to try, though if it is blushing from environmental conditions this probably won't help, since thicker product does not like to go down in thinner layers. It might be nice to try it just to eliminate the reducer as a source of trouble.
 
I had black epoxy blush last summer in high heat & humidity. I was building a surface on old HD fiberglass saddle bags using 2 un-reduced coats at a time. It didn't happen till I moved everything into the sun for some heat. I didn't consider it a problem but after an hour or two in the sun/heat it disappeared.
 
shine;29540 said:
man we fought it for years. sometimes we would be shooting so hot with retarder we would melt stripes. shooting a whole car in lacquer was pure pia . there were days when we just had to give it up and go home.
Click to expand...
I hate to date myself but I started with lacquer and straight enamel and high humidity was lacquer's worst enemy. Used the slowest thinner and retarder and like you said sometimes you just couldn't paint.
 
I remember painting a Pontiac Catalina lacquer about this time of year. Gold with a white top. The gold matched the top.
 
My lacquer days were in SoCal in the early 80's. The only time lacquer would blush was during a rainstorm in the cold. Our shops were usually open to the weather. Heat lamps and slow thinner worked fine for spot jobs.
 
Old Soul, just a thought but another thing that can help prevent this is a longer induction time.
 
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