GlenYappa

For my first painting project I decided I would paint the bottom and engine bay of my car. The thinking was if I really screw it up it is the BOTTOM of the car. Anyway I sandblasted the whole bottom of my car and the engine bay. Cleaned with paint prep. In a makeshift paintbooth (no climate control) I sprayed a sealer, 2 coats of primer, and a couple a coats of Chassis Black. I used an inexpensive automotive paint. They had a product just for the chassis. It looked like I did a petty descent job. I also painted some suspension parts and engine brackets as well. Some of these items were painted weeks apart.
Anyway the paint on all of these parts seems not very strong. Maybe soft would be the right adjective. if you just nick it or tighten a bolt against it it just goes straight to the primer or the metal. Very easy to put nicks into. It clearly isn't going to hold up to any street use.
What do you think I did wrong? Any certain bad spray technique or lack of technique cause this kind of problem? Wrong painting conditions?
I am going to sand it down and shoot it again. Any particular products you guys have had success with in this area? Any suggestions?

Glen

kretos

get a higer quality paint, i would also hazard a guess and say you painted when it was too cold, it causes the paint to take longer to fully set.

also when done set up a few heaters where the car is and leave it for a while, it'll help cure the paint

DanTheMan_smlk

but how cold could it be this time of the year?

JeffW

july in georgia i doubt its cold its nasty hot here in new england.... sounds like an adhesion problem or compatability issue. what i would do is not worry about chassis black and just get the same product line you used for primer and sealer and shoot their black on the primer and the you can flatten the clear coat so its a dull look. and it would hold up pretty good. or for suspension parts and under car get POR-15 great stuff lays out smooth and protects and won;t chip much very hard better than paint.

how long did your primer sit before base coat? did you sand the primer before base coat? what grit? sounds like the paint would not adhere to the primer.

jeff

GlenYappa

Thanks for the replies. I actually painted it over last summer then I went back to work on the engine. It's really slow going on the car (2 kids, retirement fund, college funds - I know "Wahh!"). I followed all the timelines as far as putting the color on the primer etc. I didn't sand at all between the primer and color. I figured it was the underside of the car. It was plenty hot when I shot the car. It may have been borderline too cold when I shot the suspension and engine brackets. They all seem to have the same result though. I guess I'll just try again and triple check all the times and mixing ratios.

it's wicked hot now and of course in Georgia there is a thunderstorm every afternoon and the humidity is sky high.

The Chassis black, sealer, and primer were all the same brand.
Glen

irocbirdbuilder

Sounds like it just wont set up, staying soft, could be the paint might be the mixing ratios or heat, i would shoot one part like scrap and just adjust it and keep trying at it till it decides to set up correctly.

My dad did the entire suspension components on his 81Z28 with good krylon and primer, looks awesome and has held up well for what little street time it sees though, too everything apart, prepped it and painted it and the car has won a few awards so it cant be all that bad

KissThis

Well Sand blasting it was a bad idea, that makes pits and orange peeling effect. the Humidity might also be a problem as well.

Angelis83LT

depends on the media he used when blasting it.. People norammly call everything sand blasting whethere they are using sand, silica, ceramic, glass, ect....

89_ho_rs

would a hardener have helped him out?

NoItsNotForSale

iTrader: (1)

Some kind of catalyst had to be used I hope. Why seal then prime, should have primed then sealed right?

@ZZKKER

iTrader: (1)

some primers do seal, but most "primers" are like high build for sanding to make the panel strait. the sealers like ppg's epoxie primer actually bonds to the panel and the primer will bond to it making everything stick better. also, sealer will help keep rust down.
as far as the paint being soft, either the right hardner and catilyst was not used or it was mix improperly.

thanks

911rsq

True, but he was working on the bottom side of the car. I don't think that orange peel was a major concern...

VILeninDM

Glen,

I am in the middle of doing the same thing you are. Actually I am still blasting the bottom of my car. I've been spending a lot of time on autobodystore.com and the guys over there swear by Zero Rust. I've been blasting protions and conditioning them with phosphoric acid/zinc solution so they don't get flash rust while I am doing the rest. After this, will apply ZR stuff directly to metal. According to them, there is no sealer or primer. That stuff is specifically designed to go directly to metal (and even surface rust in some cases).

It is kinda like Por-15, but I've been talking to a lot of people, in addition to autobodstore.com, and a lot, don't like Por-15 or other (moisture-cured urethanes, I think that's what it is based on). ZR is a completely different product.


While we are on the subject, how did you blast the bottom of the car? I would appreciate comments here. Don't want to hijack your thread.