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Discussion Starter #1
I was painting my bike and I have fog spots on it. I tried wet sanding, polishing and buffing. Nothing will get the spots out. The only thing I can think of is when I was painting it was high humidity and it started raining when I was throwing the final coat on. I don't want to have to repaint everything, but will I?

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1980 Honda CB750
1972 Oldsmobile 442
 

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did you do a base coat / clear coat or is it single stage rattle can? If it is rattle can sounds to me like you either:

did not clean the surface properly (with rattle can enamel 100% mineral spirits are the best cleaner)

or

did not wait long enough to dry between coats.

my best expirence with spray cans has always been between 60 and 72 degrees, with me running the spray can under a hot tap for 10 minutes prior to shaking, and then letting it dry 1 full day between coats. Also I wetsand between coats (starting at 600 and working my way up to 2000) and clean with mineral spirits.

Try wetsanding with 600, then 1000, then 1200 and see if it takes it out. If not dry sand with 300 grit down a few layers and then lay on some new coats.

If using rustoleum, I find that 6-8 layers of paint is good for a hard shine you can wetsand and polish.
 

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geeto, you're a perfectionist aint ya?

basically your paint job is "infected". depending on what you used (rattle or real paint) you might have to start over. if i were you, i'd do it inside the garage too. humidity would not have left spots like this. you could have had some oil or whatever impurities on the tank or, like the painter at the body shop at my work, you could have had a diesel bus running right outside your air intake for your paintbooth and it would fuck you up. if nothing happens when you wet sand it or whatever, then you'll have ta sand the bitch down a bit to a smooth butt and clean the sucka with mineral spirit (doesnt necessarily have to be at 100%, some paints work better with 50%) and then reshoot it. how big are the spots? are they darker, lighter or more like a haze? depending on what kind of paint and where you got it from it could also be old paint which might have fucked chem composition.

CB650, FauxCatiFT500
 

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its called blush or blooming. you captured humidity in the air. you didnt use enough yes, im going to say it, retardant. what i have done on cabinet jobs in the past is spray straight retardant onto the job. it will re-emulsify the paint, and let the moisture out. but its risky. you can definitely fuck it up. you could try about a 75% retardant/25% finish and see if that works. or you could try shooting just straight thinner. blushing is very common in high humidity environments. you cant sand it out because its actually under the finish and bleads through. especially on clear coats. one solution is to use waterbased stuff. but its expensive and much harder to work with. so the learning curve is a little bigger. but guys i know who use the stuff love it. but contrary to what jb is saying, yes, it is absolutly possible to capture humidity in the finish and have it blush. its very very common.

the ppg site has a pretty good library.


http://www.ppg.com/PDSMaxMeyer/Show...e=44&ProcessStage=8&ShowPicture=0&DefectId=82

jc

"tex, if your bikes a cheater, its not a very good one"
 

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Yep, every time I've run into that problem it's been humidity....just did it again touching up my truck on an 80 degree day with about 80% humidity. The instuctions on the paint...where it says don't paint in high humidity...they mean it.
JohnnyB
 

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see, thats not true. you just need to use some kind of drying/curing retardant. something that will slow the curing a bit so the moisture can escape. real paints use retardants. but you can use thinner. august paint jobs require alot of retardant. and sometimes i have to hit things with straight up retardant. they also make laquer thinners that have different drying times. home depot will sell you medium. which can work. you can shoot in high humidity environments. you just need to use the right stuff. and it will take alot longer to tack up. or dry in, or whatever you want to call it.

i dont know alot about it, but with furniture and cabinets, it really shows, and can really screw up a nice piece. so ive delt with it a little. 99% of the time in summer though.

jc

jc

"tex, if your bikes a cheater, its not a very good one"
 

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Discussion Starter #7
Acctually it was a rattle can job. Other than the fog spots the paint looks amazing. The only other problem is I knew there was a few dings in my tank but the gloss black REALLY brings those dents out into notice. What I'm going to do is strip it down to metal, skim everything with bondo so I get a nice smooth paint this time. Plus the "all black" thing was a little much, I came up with a new paint scheme that should look great. It just sucks cause it turned out amazing other than the fog spots and dents.

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1980 Honda CB750
1972 Oldsmobile 442
 

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You can also try aiming a hairdryer or electric heater at the affected spot for awhile. I've seen that take care of moisture problems in OEM paint. We had to do one overnight with a space heater placed about 3 feet from the car, but it worked. Low heat for a long time.



FR
 

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Joe...the instructions are for retarded painters like me. So when they say don't paint in high humidity...they mean it.

Every time I've ever used retarder the paint ends up all running on to the floor :)
But I get some nice wet coats at first.
JohnnyB
 

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but its great, cuz it runs all weird and flailing.

i used to never used any retardant. then a friend of mine whos done alot of finishing convinced me to use it. i used to just paint with thinner. the problem with the thinner is it seems to atomize and create dust. it dries in the air before it can lay up. retardant stays with the paint. and the big benefit is it will make your paint lay down flatter since it gives it time. so less orange peel and less sanding and buffing. there are furniture guys who shoot paint that ive seen lay it up so perfectly it doesnt need anything. but those are guys with like $1000 guns who spend 10 hours a day in the booth. theres a big big difference between them, me, you and even steve d'.

id imagine you can have moisture issues with rattle cans too. especially black. any painter will tell you, black is the most difficult to make look good. i cant see why some very low deriect heat wouldnt work either. to bake the moisture out. never tried it though.

jc

"tex, if your bikes a cheater, its not a very good one"
 

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everything you guys said...used to spray nitro-celulose lacqueur...the fine lines between drying time, moisture, heat, solvent, fish-eye, orange peel, and astrology was mind bending. got really good for a few years but now...the new chemistry yields great finishes with greater ease...rattle cans love good weather. wait for a good day next time.
 

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rattle cans love no wind paint in the morning when wind is at its lowest,that why rattle cans are good, you can touch up cheaply.
The thing that helps make a good painter is, lots of screw ups ,and knowing his enviroment, he paints in .After a while a good painter becomes one with is enviroment and he can pull off great feats ,mixing and shooting paint that has no flaws and can fix flaws when they do surface, quickly.
The casual painter can have success painting but ussually has compounded problems when problems do arise.
rattle can to glory, its cheap,real paint is expensive.

Im so far behind ,that I think Im in first.
 

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never had any problems with moisture in "spots".... only seen it sort of wide areas. new to me. i repainted the 500 last summer, maryland summer, and besides for not cleaning me sharpe well enough between clear coats, turned out great. around 70-80% humidity outside, while in the garage i had the usual fans going.

but he's doing the rattle can.... shit, honky lips, get yourself some rustoleums and high density foam rollers for your next attempt.

CB650, FauxCatiFT500
 
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