Please advise paint prep steps\products

aftermath · aftermath's Garage

Im going to repaint a project 944 car I bought for my son. Its galvanized....I have one rust repair to make ( cutting out some sheet metal ) and a few spots not rusted through but under the paint and maybe on the backside of the panel.

I was hearing about water based paints ( not toxic ) that I can do at home, in several coats and wet sand to make up for my poor spraying techniques - product recommendations?

I know that I have to get rid of the rust, wire brush will be what I use. But that does \ can leave some rust in the pitted areas. So how do I prep that - product recommendation for a galvanized body? Then I need to prime so that it doesnt flash rust - product recommendation for a galvanized body?

Im most concerned about rust coming back. These steps also will apply to my race car, I have melted the undercoating off the car where some plates were welded in for the cage and I already see some surface rust.

962porsche · 10-22-2010, 02:37 PM

if your thinking of a water born base colors you will need allot of things to make the system work as it should . if your going to paint it out side of a booth i would go with the solvent base color . i would go out and get a little spot sand blaster there about 35 dollars .if your going to try to use a wire wheel the rust will be back in no time making all your work for not . when it comes to galvanized panels try not to get down to the metal when ever you can . the galvanized coatig is so thin you will sand it off quick and ez . there are body fillers that work real good on galvanized panels look for one of them . just about any E-coat primer works for galvanized panels .

aftermath · aftermath's Garage

I have a big compressor and sand blaster. Ok solvent based....So if I sand paint, bring the rusted areas down to metal with sand blaster. Then maybe por-15 over the rusted areas. Then prime, block, paint? I understand a lot of the process, just not which products to use at home. I used to have access to a paint booth from one of my sponsors and a friend who would spray, but now Im on my own....

MrJTP · 10-22-2010, 05:45 PM

Read the entire Freddie Hernandez' 101 series at the top of this forum. It will certainly get you started.

Fishcop · Fishcop's Garage

Hi Aftermath,

Visit your local jobber/paint supply place and choose a good brand's "system"... PPG, Glasurit, BSA... whatever. Stick to the MSD and tech sheets supplied and you'll be fine.

Pretty much all systems require bare metal (sanding/blasting), you begin with their epoxy based primer which sticks like sh.. to a blanket. Unlike old tech paints it's waterproof and the work can sit literally for years (undercover). Preferably you then lay their urethane build primer within the "window" of the epoxy's drying time which means you don't have to sand. There is a whole bunch of opinion on using filler over or under epoxy - follow the manufacturer's directions and you can't go wrong. Block sand. Top coat (single stage or clear over base).

This is a great forum for discussing bodywork and paint Autobodystore Forums

I'm no expert and don't claim to be - but this seems to be working really well for me and beats the old skool etch-primer systems hands down.

962porsche · 09:33 PM

i would not por-15 right over the bare metal . no need . after you sand blast . do your welding and plastic work (bodyfiller) then use a etch or epoxy primer over that ( with most E-primers only one coat is needed ) then using a high build primer spray 3 to 4 coats . when spraying primers do not stop your spray pattern in the same place . what and how it should be done is say the spot you want to prime is 12inches do your 1st coat the hole 12 inchs then on the next coat step it in about 2 inches . this means that the 2nd coat your only spraying 10 inchs long . then on the 3rd coat you only spray 8 inches . so each coat starts and ends just a little shorter than the last coat you sprayed . doing it this way you will get less of an abrupt edge from old finish to primer making for less waves in the finish . also by starting with you sirts coat going all the way out you will not be putting wet primer on the dry overspray edge from the coats before . if you use a E-primer and you should use one that is chromated and with an activator . as stated get some TDS sheets with the products you are going to use . try not to mix and match product lines if you want to use say BASF (glasurit / RM ) then use all there sprayables (primers and top coats ). also you should remember is that not all advice that you get from forums like autobodystore is right . off the top of my head the last time i was on that forum there was a person that had orange peal and was told it would be ok to da sand the finish with 400 dry paper and clear over the top . thats just wrong !! so do your home work .

rickharrison · 10-23-2010, 04:57 PM

I decided to test the POR15 stuff on my winter beater, a 1999 Exploder, er Explorer.

Right at the front left wheel well, where the plastic fender flair joins the paint, it was chipped off and the surface was rusty.

I used the kit, and have left it since June this year.

To date...no re-occurance of rust there. It damn good stuff methinks!

The kit says you can prime over top of the POR15 and continue on finishing.

Maybe in the spring I'll follow through and post up the full project. I really want to see how it lasts through our winter up here.

962...think the top coats will react with the POR15?

962porsche · 10-24-2010, 06:01 AM

i don't think you will have a problem with top coating por-15 . i have stated on some posts that i'm not a big fan of the por-15 product line and i'm not ! i have and do use it at times . por-15 is like the craz when dupont introduced there imron line in the 80's . there not the 1st or the best to offer that kind of product . but with marketing the public thinks they are . does por-15 work YES but any product should if you follow the TDS . it comes down to cost (twice as much as other products that do the same thing )and as a shop owner for a long ass time i have never seen a por-15 rep.

ratpiper71T · 10-24-2010, 08:18 AM

Quote:

i would not por-15 right over the bare metal . no need . after you sand blast . do your welding and plastic work (bodyfiller) then use a etch or epoxy primer over that ( with most E-primers only one coat is needed ) then using a high build primer spray 3 to 4 coats . when spraying primers do not stop your spray pattern in the same place . what and how it should be done is say the spot you want to prime is 12inches do your 1st coat the hole 12 inchs then on the next coat step it in about 2 inches . this means that the 2nd coat your only spraying 10 inchs long . then on the 3rd coat you only spray 8 inches . so each coat starts and ends just a little shorter than the last coat you sprayed . doing it this way you will get less of an abrupt edge from old finish to primer making for less waves in the finish . also by starting with you sirts coat going all the way out you will not be putting wet primer on the dry overspray edge from the coats before . if you use a E-primer and you should use one that is chromated and with an activator . as stated get some TDS sheets with the products you are going to use . try not to mix and match product lines if you want to use say BASF (glasurit / RM ) then use all there sprayables (primers and top coats ). also you should remember is that not all advice that you get from forums like autobodystore is right . off the top of my head the last time i was on that forum there was a person that had orange peal and was told it would be ok to da sand the finish with 400 dry paper and clear over the top . thats just wrong !! so do your home work .

962 would you say it's acceptable to spray epoxy after welding and rust treatment, but before plastic- bond and filler work- like Freddie suggests? I know theirs alot of opinions on this and most say plastic then epoxy, but. For most DIYers like myself it may take weeks or months to do body work and blocking stage...

962porsche · 10-24-2010, 12:57 PM

i would opt more for an activated and chromated etch primer then a epoxy primer for going under my body filler . but yes you can in most cases . you should alway check the TDS for the product your using . becouse most E-primers only need one and no more than two coats there is very little mill build to the prime . a E-primer is more for adhesion unless its a chromated product as well . then the chromates will help to combat rust .

ratpiper71T · 10-24-2010, 01:18 PM

Quote:

i would opt more for an activated and chromated etch primer then a epoxy primer for going under my body filler . but yes you can in most cases . you should alway check the TDS for the product your using . becouse most E-primers only need one and no more than two coats there is very little mill build to the prime . a E-primer is more for adhesion unless its a chromated product as well . then the chromates will help to combat rust .

When you say e-primer are you referring to epoxy or etch? And can an etch or chromated primer be left for a significant amount of time while plastic or filler work completed.or better yet which can?

AfterMath- forgive the highjack I hope you don't mind as he ?s are in line with yours