XtinctZ28

iTrader: (57)

Can I prime something with a high build primer from a rattle can, sand/prep it then have a shop spray an actual automotive finish over it?

Will it stay, or do I need a higher grade automotive primer for the paint to adhere correctly?

Thanks in advance for any help.

steelhorses

iTrader: (2)

how big is it? if it's something relatively small, then i don't think it would be too much of a deal. however if you're talking something big like a hood or fender or something i'd go with the automotive primer. especially because most paint lines have designed their whole paint systems to work together. that's why you don't really want to put dupont primer on, with ppg base, and hok clear. sure, it might work, but do you really want to take the chance? not with expensive stuff like that.
i'm not a professional, but i took two years of autobody school, so i'd like to think i know a fair amount of what i'm talking about. but maybe a pro will chime in, too

XtinctZ28

iTrader: (57)

Out of all the parts the largest part would be a fuel rail cover, so not very big items.

Probably OK to go ahead then?

steelhorses

iTrader: (2)

i would think so. if you're having a shop paint it you might want to ask them first and see if they'll make big deal out of it...
a) either they're going to be fine with it and just paint the parts... or
b) they will sand off whatever primer you put on and spray on a higher quality primer

just call them and ask them. that would be the easiest way to go, that way you can save some money on not buying primer if they're just going to sand it off.

if you spray it yourself just make sure you've got the right grit paper so that the primer has something to "bite" into. that will help with the adhesion.

O-townLS1

If you use actual car paint over rattle can primer it will spider web or have whats called the "lightening effect". Makes it look like leather. If your going to do it then do it right and go with auto primer.

redramair98

iTrader: (74)

def use good high build primer and adhesion promoter on plastic parts, and if its rattle can its gona be soem kind of laquer based primer which might cause problems for durability, the shop painting it etc

jkwalkercchs

iTrader: (21)

ok on plastic

180 grit do not get to hot u will bring mold release agents to surface if using a da go slow
then clean with soap and a scotchbrite
clean again with water and scothbrite
clean again with acohol based grease remover i use 91% alcohol
adhesion promoter
flexible primer surfacer
wet sand with 400
clean with soap and water
clean again with alcohol based cleaner
flexible sealer
then base (i use ppg it doesnt need flex in the base)
then clear with flex additive


no rattle cans unless u need a guide coat to wetsand by lol

im not tryin to be an *** im just speaking from experience painting plastic right the first time saves lots of time and money

steelhorses

iTrader: (2)

i'm curious... what's the point of sanding it with 180 grit paper, then using soapy water and a scotchbrite, then just water and scotchbrite???? 180 isn't exactly smooth, so you don't really need the scotchbrite to scuff up anything. i saw in another post you're ppg certified, so you know what you're doing, it's just that while i was in school we never did that or added flex additive to any of the paints/primers. we, did wipe an adhesion promoter on lots of bigger plastic pieces like bumpers, etc, but never used a flex additive.
i'm just trying to understand what you're reasoning is behind it.

jkwalkercchs

iTrader: (21)

because you arent using the scothbrite to smooth it out u are using it do get into the grooves and knock of the little fuzzys that happen when sanding it

because with plastic the main thing is cleanliness because any left over soap residue will cause adhesion problems
when painting u should spend more time cleaning the part and booth then spraying it

yea u must add flex additive unlest u like to see your pretty peice of art turn into **** months down the road
without it--it will look good and flex some but thats because it hasnt truley 100% cured so when it does finally cure completely then u will have some cracking

steelhorses

iTrader: (2)

ok, that's kinda what i was thinking the scotchbrite was for. and i agree with the cleaning thing. can't have anything too clean.

my instructor told me that the only good the flex additive is for is for when you are mounting things, or you know, before it has really cured. after it has cured it doesn't do anything. any truth to that??? it seems like once everything has cured a flex additive wouldn't help, at least in my thinking, but i could be wrong.

jkwalkercchs

iTrader: (21)

no flex additive actually changes the moleculaur structure of the paint