Spray paint question

[AustinF19]

So over the last two weeks i have been working on repainting all the plastics on my bike. The fairing were scratched up pretty bad so i sanded everything down to the plastic, rinsed it off with some cleaners and water. The Paint i am using is all Dupli-Color automotive spraypaint (I dont have money to spend on high quality paint). anyway i laid down 3 or 4 coats of primer on each piece and let that sit over the weekend. I picked up some black glossy for the color, and the first 2 coats looked good when they dried yesterday, but today when i laid down the 3rd coat there was grey and white splotches and streaks all over once it dried. (happened from 2 different cans). Does this usually happen or could i have done something wrong? This is the first time i have taken my time and painted anything big so i am no pro. Also it was quite humid outside today when i was painting, dont know if that could affect paint that much

[Wild-Bill]

Humidity definitely has an effect although I've never had that sort of result. Hit the search and look up painting. There's some pros on here who can probably explain it.

[teddy]

Why so much primer? A single even coat is plenty. Too late now, but just keep that in mind the next time.

Humidity and temperature will play a HUGE role in how paint lays out, cures, adheres, and finishes. Sounds like you got the short end on this one. How long exactly did your primer sit before painting? What primer did you use? Did you mix a lacquer and an enamel? Too many variables right now to give you a definite answer as to what went wrong. I'm not a pro, but can paint rather decent, and I mix and sell paint where I work. TMcCall on here is a pro painter, hopefully he'll chime in soon.

You said it looked good after two coats, why did you go for a third? On the back of the can it probably has re-coat instructions, did you follow them, or just start spraying? Most rattle can paints I've seen want a re-coat withing a couple hours at max, otherwise you'll need to sand and start over. My over-the-internet guess is you re coated too heavy in some areas, and light in others, mixed along with the temp/humidity, and the fact the solvents were curing out of the existing coats...haze and fog appeared. Now, you might be able to get out of this. Do you have access to a buffer? If you do, wait a day or two and wetsand it with 1500grit, and try buffing it with a light buffing compound and a foam pad. It doesn't hurt to try, because even if it doesn't work, you'll be sanding it down again anyway...but you might get lucky...hard to say...

[AustinF19]

I talked to guy who owns a body and paint shop, he said put on a couple layers of primer to get the best finish, All the parts sat for 2 days and then i did some wet sanding to smooth out deep scratches, rinsed it and let it dry in the sun for about 4 hours and then put down the first 2 layers then let it sit over night, today put on a 3rd layer and got the foggy/ grey finish in some areas. after 2 coats the paint it self was good( clear and shiny) but the pieces were not 100% covered yet,still had some light spots

[T McCall]

Like Teddy said, dont wait to clear.
Really dont know much about spray cans but would assume about the same.See people on here waiting days and such to clear, just asking for trouble.Follow the recomended application times if they supply that
Sounds like you're experiencing " blushing".Hard to tell without seeing it.
Un fortunatley you cant adjust spray cans with different temp reducers and hardeners to cooperate with conditions.
In some cases i have seen the clear eliminate blushing.
Spray your color, follow up with clear right away.
Try 1 pc 1st , see how it goes.

[ErrEs]

Were you at the end of a can? Did you shake it up from time to time? Did you keep the can vertically or horisontally? All these variables can have their effect on the outcome.

If you used filler primer you're supposed to do several layers to get an even fill/build-up in the cracks and scratches. I did as much as four layers to get a smooth result.

[AustinF19]

I was nearing the end of one can, stopped shook up a new one for a few minutes and had the same results on a different piece. i was holding the cans vertical to the ground

[Mojoe]

I am betting you didn't do anything wrong. that's just duplicolor for you. I tried painting some rims with it once and had to fight like a biatch to get shine. took me like 2 cans per rim to a decent shine, and was worried I would have to crack open a 3rd.

ever see the reducers and hardeners they use in rattle cans? it's not clear like like 2 stage paint you mix yourself. it's actually a milky color, and it is has a different chemistry. it has to because it has to have a shelf life up to two years I think it is, yet cure in a reasonable amount of time once used.

duplicolor clear is the same thing.....you almost have to be lucky for it not to go milky on you when it dries.

[scottynoface]

duplicolor clear is the same thing.....you almost have to be lucky for it not to go milky on you when it dries.

Mine on my solo cowl actually came out really nicely.

However, it has already gotten gouged after throwing my leg over it 3 times, so...

[Kreylyn]

2 major things...

1. The instructions on the can say spray next coat with in 2 hours or wait 7 days. This is why.

2. My experiance with duplicolor is that the milky (white) will go away as it cures unless you mixed paint brands... So in a day or 2 if you didn't touch it, you MIGHT find that it is no longer milky looking. If you didn't put enough of a coat on though, the "flat" or "dull" overspray look won't just go away. That will get worse looking as it cures.

Krey

[ErrEs]

When I sprayed my bike I found that at the end of a can there is less pressure and you have to shake a lot more between sprays and a lot longer too.
Because of low pressure the paint is mixed less with gas and creates drops. This is increased when you don't spray horisontally.
When your can is over half empty it's best hang your piece to spray straight ahead instead of towards the ground.
A little wet sanding should take care of it though.

Another way to avoid this is not spraying at a constant rate. Go from left to right and back and stop in between passes.
Also make sure you start/stop when you are outside the spraying area. Most drops come out at the beginning of a spray or at the end.
This way they don't land on your piece of bodywork.

I din't have the impression this is brand related though, but I can't tell for sure.

[AustinF19]

Oh i did not see that on the can, Sould i wet sand it down to the primer and start over? or what would be the best way to fix this?

[Kreylyn]

Oh i did not see that on the can, Sould i wet sand it down to the primer and start over? or what would be the best way to fix this?

Depends on your time schedule...

If you have a few days I would wait and see if the milky clears. If it does, then follow the instructions for future coats and go from there.

If it does not, then wait for the coat to cure if you can (generally says the time on the can) and then a light sanding if needed to smooth it out and recoat.

If you have to have it done asap... then your looking at probably needing to get most of the prior coat off before you can start again.

Me... I would wait a little bit and give it some time. Significantly less work either way out of the first 2 choices if you have the time.

Krey

[hardlydangerous]

most people do not shake spray paints nearly long enough... most shake for 30 seconds or a minute. Thats not enough. If not properly mixed the solvents will destroy the under layers of paint....

shake 2-3 minutes, warm up the paints by setting them in hot water shake for 2-3 more minutes. then spray.

[scottynoface]

warm up the paints by setting them in hot water shake for 2-3 more minutes. then spray.

I never believed this till I tried it, it makes a big difference in the uniformity of the spray...