Dirt under primer. What to do
 

So I have a project car n my garage that I am completely restoring. I've painted engine bay 3 times until I got it the way I want it. I'm a rookie at this so it took a little while to get used to the gun and the feel for everything. Well last nite some how I forgot to wipe down the car before spraying (idiot, and I have 2 gallons of prep all sitting there jus for that), so there was sanding dust on car when I started to primer. Only sprayed rear quarter panel before I realized and slapped myself, now what? Do I need to strip the primer and start over or do I sand it smooth again. Thanks

Re: Dirt under primer. What to do
 

I personaly would sand it down out of fear for the paint flaking off because it could not adhear to the metal becasue of the dust. especially if its just one panel.

Re: Dirt under primer. What to do
 

sand it all down bro ! only way it will look good and last:)

Re: Dirt under primer. What to do
 

Back to square one. Lol. Hate doin double work but hate being unsatisfied more. Time to start sanding.

Re: Dirt under primer. What to do
 

haha i know what your going threw...

check my paint work i did on my da lol its rattle can but hey it looks good

goodluck on the paint bro

Re: Dirt under primer. What to do
 

Dayum... Rattle can shinnin. Lol. I'm a pretty patient person. I would much rather do it as many times as needed than to have a fugged up paint job. Thanks. I'll post up pics in my build thread when it's done right

Re: Dirt under primer. What to do
 

yeah its shinnin lol

Re: Dirt under primer. What to do
 

just block sand it, it's no biggie. it'll be smoother anyway and look that much better

Re: Dirt under primer. What to do
 

^^ r u saying jus to smooth it out, kinda sand the dirt off but not all the way back down to it's original color, I know the primer is bonded real well to the car cuz its not coming off to easy with 80 grit.

Re: Dirt under primer. What to do
 

i wouldn't use 80 grit on primer, but then i again i don't know how far along your body work is. i'd block sand it with 180-220

Re: Dirt under primer. What to do
 

I'm so confused by this...

Dirt underneath primer doesn't matter at all. Primer always gets put on heavy and thick and then must be block sanded smooth. Primer is nothing more than the last step in body work. When priming, you only need to make sure the surface is free of wax or grease and there are no pinholes in the body work... other than that, primer can be sloppy. You don't need to worry about dust when priming.

If you're talking about sealer - the first liquid step in paint work - then yes, dirt underneath the sealer is a problem as it will show through into the base and then appear as a nib in the clear coat. some dirt nibs are okay to have with certain colors because you can easily wet sand them out of the clear.

If you have a ton of dirt under the sealer that you're sure will be an issue later on, then just make sure it's cured all the way (the product's tech sheet will tell you how many hours until re-sand) and then just re-prep the surface with whatever grit you're using on the DA for prep. I would just re-sand it with 400 grit on your DA and then *blow it off and wipe it down* and then re-seal it then go from there. You don't need to remove anything, just sand out the dirt nibs and sand the rest of the area smooth, then scuff the rest... it's standard prep work again once the sealer is cured.

I don't know where some of this nonsense comes from but some of you should really hold off on the advice-giving until you know what you're talking about.

Re: Dirt under primer. What to do
 

many people prime>scuff>seal>base>clear, i know its not proper but its been done

Re: Dirt under primer. What to do
 

People have also painted cars with Rustoleum. I've even heard of a guy making rust filler panels with paper mache. Both are just as stupid as only scuffing primer before paint. It's purposely ruining a paint job. No matter how finely you try to atomize the primer, it's a thick material which will build on the surface and only amplify the imperfections underneath.

Primer is only applied to a surface that you wish to remove imperfections from. You apply it thick with the intent to block sand it smooth. There's no other proper use of primer. Like I said, sealer is applied as the first step in paint work, which at that point is over a perfectly smooth surface. There are a few materials companies out there who market a 'multi-option' primer product, like Keystone's 3-in-1 primer surfacer/sealer, but it's not a true sealer that's made to work wet-on-wet in a paint system. Those 'sealers' are just thinned down surfacer which will still need to be blocked out or as least machine sanded before it's smooth enough for paint.

Standard Operating Procedures do not vary greatly between equally competent professionals. No matter what shop you walk into, you will always see primer being used as a surfacer to be block sanded in preparation for sealer and base. Anyone who does it any differently than that is ruining a paint job either out of incompetence or laziness or both.

Re: Dirt under primer. What to do
 

i understand that, i work in a custom truck and rod shop- i know paint. i'm just explaining that not EVERYONE has the same procedure. when i first started painting, i primed>scuffed>painted so i understand where the op is coming from.. i'm not saying that you're wrong, i'm just trying to make sure you understand what op is doing