Re-Spray And Paint Types

[xXDazXx]

Hey guys, thinking of respraying my ute in near future but i have a couple of questions.

Painting straight over original paint with only spot priming repairs? a mate just had a full respray done and thats all they did. I always thought it would flake off withen 6mnths? without proper priming? mattellic'd over sanded topcoat.
Has anyone heard of using 2k polyester undercoat as a base? a couple people i know have said to just use it instead of primer because its alot cheaper. seen a car done about a year ago in evic 750 poly about a year ago lol.. was kinda suprised as its for made for wood/mdf in the 750 series.. didnt seem to be coming off either lol.

Im going to be getting my paint from Harts or Protec when I do mine and strip it right back. But just wanted to hear some oppinions on what ive heard recently.

 

[WazzaVN]

Re spraying over 2 pack topcoat is fine as long as you scuff it properly. (Assuming this is your vz)

Poly is not primer. It is a polyester spray. You can't put topcoat over it because it will soak it up and look ****. You have to prime over it first.

 

[xXDazXx]

well thats the thing, the jobs ive seen in it turned out amazing because its such highbuild and set so hard. just wanted to see if anyone else had done anything like that. i think we are thinking about different stuff.

 

[ari666]

i just sprayed a bunch of poly on my 1/4's and it reacted really badly to the underlying paint work.

granted it was going over acrylic paint, but the acrylic was over 2 years old and had a chance to bake in summer and freeze in winter. im told the reason it flared in spots is because that particular area was thicker (more coats) acrylic and the solvent in the poly was able to get inside the layers.

so far from what i can garner:
poly is good because its a VERY high build and goes off rapidly (ready for paint in 24 hours) however ideally it can only be used on steel (you can get away with bog) but using it over paint or etch primer is a no-no. since its just liquid bog, you need to prime over it later anyway.

hi-fill is good because its cheap. whoever told you poly is cheap is high on paint fumes. poly is around $170 for 2.5kgs, hi-fill is 5kg for 80 bucks, so 1/4 of the price, not only do you get more, it also goes a lot further. dont forget that to use poly youll need a poly gun and the stuff comes out like stoneguard. lumpy as all fk and you waste about 1/3 of your material just knocking the top off. coverage is pretty shitty. but, as poly is good to go in 24 hours, hi-fill takes AGGGGGGGES to properly go off. you can wait weeks for it to properley set. some areas on my firewall and dash have "sunk in" even though it was around 2 weeks of sitting in 30-40 degree heat.

as with anything, you need to watch your build-level. people spot over old paint so theyre not building too high. not only that makes life much easier when youre not sanding back to metal. but if you CBF doing a bare metal:

scrub it all off:
poly the whole thing
spot filler any real bad stuff
hi-fill
paint

otherwise just scrub and spot prime.

 

[hi_ryder]

what he said^^^

polyester primer is solely designed to be block sanded. basically you use it if your car is edge to edge bog and you want it straight, and even then as above you have to prime over it. use 2k primer on any bog repairs or places you've cut through the old 2k paint. its perfectly fine to rub your old 2k finish and paint right over it.

 

[xXDazXx]

yeah ok. when i do mine ill probs cut it right back and just reprime etc not worry about poly. Just thought id get some oppinions on it first. The price for the poly the guys have been saying is actually complete opposite to yours like 25kg for 300$ lol. so it wasnt that bad fpr price considering.