is it o k to cover a car in spray can primer? i stripped the car down to bare metal and have removed all of the previous bodywork, only trouble is that the metal started to rust after a while. a trip to pep boys and i had 10 cans of black primer. i sanded down the metal, preped it and taped it, then shot it. was this a good idea? will this stuff last or am i wasting my time? will i have to sand it off again when i prime it for real? thanks.

john

John,
Any primer that I have had experiences with that came out of a spray can have not been good. That is not to say that all spray can primers are bad, just that I haven't found any good ones.
The primer is usually too thin to be of any value, is very pourous and prone to allowing rust and the adhesion is very poor.
I wouldn't want to use any that I have seen as a foundation for any other primer or paint.
If cost is a concern, have you thought about renting a compressor and spray gun? I know this isn't a very good option either but I thing using a quality primer and appling it with rented equipment is better than a spray can.

John - If you've got a Sherwin-Williams automotive coatings shop nearby, check with them. They sell a zinc based self-etching primer in a can that etches into bare metal and gives decent adhesion. It is very thin though and doesn't "seal". If left exposed for an extended period of time it will still rust. I've used this stuff to control flash rusting on bare metal and it worked well.

Hi, John, there was an exact question asked a while back, click on the link below, there are some interesting suggestion's on this since a lot of us have or will be in this predicament, of body work.
http://www.chevelles.com/forum/Forum3/HTML/003324.html

Hey John, I did the exact same thing to my 69', after stripping it down to metal, you have to cover it with something. I'm pretty sure I used the Rustoleum automotive primer, the guy at Home Depot swares by it! Any way you look at it, it's better than letting it sit there rusting away in bare metal!
http://www.geocities.com/kz1000ltd/primer1.jpg

OK, I've got the idea on what to do and how to 'prepare' the bare metal for paint. I'm going to borrow a gun and shoot self-etching primer/surfacer on myself, or just have the guy that's gonna paint the car do it if I can afford to do both at the same time. Otherwise I'm going to shoot the thick stuff on and block it myself. No rattle cans for this important step!

What I need to know now is the best or easiest way to clean the bare metal before I shoot the primer? The car is already down to either the original primer or someone shot it and blocked it already. (poor job) I'm going to do it all over again though. I'll be doing it in my garage since there's no rearend in the car. Once the metal is bare, can I just use a good strong cleaner/degreaser or is there something better that I can get at the automotive chemical supplier? I'm thinking environmentally safe and something that won't turn my garage into a nuclear waste dump. (it has no floor drain BTW)
Any ideas what to ask for when I call them?

Thanks!



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Joe
HwyStar@Rochester.rr.com
'97 Blazer - Bad wheel hop!
'69 wallet crusher

DuPont Zinc 215 S is also a good spray bomb, but it's about $17.00 a can. I wouldn't use a regular spray bomb (like Rustoleum) on exterior sheet metal, but it's okay for under hood stuff.

Joe, DuPont's Metal Prep 5717 S is a good metal cleaning/etching conditioner.

JD

Great... thanks John.

I know the primer process is a 2 step process..... once it's at bare metal status, I use the self-etching primer, then a primer/sealer which gets blocked. Correct? As long as the metal prep went well, I should have a good base to paint?



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Joe
HwyStar@Rochester.rr.com
'97 Blazer - Bad wheel hop!
'69 wallet crusher

Joe, you can shot primer sealer right over the etch prime as long as it's within 3 hrs, otherwise you have to use a scuff pad to scuff the etch primer. Use Prep sol to clean all the panels before painting, and tac cloths to pickup any dust.

Great... Thanks Clash. My body-man is coming over this weekend to tell me what final areas need attention before I finish stripping the old primer off.



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Joe
WCA Member
HwyStar@Rochester.rr.com
'97 Blazer - Bad wheel hop!
'69 wallet crusher

I have seen some bodyshops that put on top of bare metal a yellowish base. They say it's bare metal sealer and it's suppose to protect from rust. Is that correct and is it a good idea to put that on top of metal prior to spray primer or that goes after the primer. I'm comfused.

ORENCH, yes the metal etch should be put on any bare metal before priming or sealing. Some brands are a tranparent yellow, others are a tranparent green. You don't need very much just one light to medium coat. Let it sit for about 1/2 hour (check lable) then apply primer surfacer. PPGs best metal etch is DX1791 DX1792 mixed 1 to 1.

Just thought I would add, if primer is already on there is NO benefit to using metal etch. It is only effective when sprayed dirrectly onto bare metal. It will help corrosion and adheasion on bare metal.

Thanks for the info "Austin".

I know this doesn't pertain to this discussion, but I though I would add.....

1.READ THE TECH SHEETS! Nearly every paint company I know has them on line.

2.Some etching primers CAN'T be sanded.
3.If you are using an etching primer DON'T use a metal etch, you will loose adheasion because the acids attack each other instead of the metal. If you are using an aerosol primer, I don't think this would be a problem, being I doubt it has acid in it. BUT I would look into it, maybe the MSDS sheet? It's most likey on-line too.



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Fan of anything that is interesting and moves human beings.
1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
1948 Chevy PU with 401 Buick