questions about primers

[82chevy]

ive been doing my bodywork on my truck for a few months now and have the cab all finished and painted. ive moved on the the bed and have started to remove all the rust. on the cab i used nason acrylic primer. someone on here said that it would show scratches and they were right. in some spots i can see them. i dont want to make that mistake on the bed. i see people on here using more than one primers when doing there bodywork. i was thinking about using like a high build primer also. so what would be good primers to use that i can get at carquest or a store like that. im also using an acrylic enamel for the paint if that matters

[flthead]

this what i use  http://www.akzonobelcarrefinishes.net/default.asp?sid=65395&pid=438

[Blazin]

I firmly believe in a self etching / rust inhibitive primer over bare metal. In some applications a 2 part epoxy primer. Always a 2 or three part 2K high build urethane primer to fill you final body work sand scratches. Don't use acrylic putty either. The high build primer takes place of that. I like 5 star 2K Primer / sealer. Mar Hyde also makes a very good 2K primer as well.

[82chevy]

so the areas that i did the body work i should shoot it with a self etching primer. what about the areas that i didnt take down to metal? another words should i shoot the whole bed with it or only the areas that i did the body work on?? thanks blazin for your input

[choptop]

 I spot prime the parts with the epoxy primer/ self etching primer that I have in bare metal until I have all the major work done on that panel, then I epoxy the whole thing. Then I go in with the filler primer. I am not a pro painter, but I want a good base/sealer on it before I put down the filler primer. The filler primer does not seal moisture as well as the epoxy and if there is any bare metal, the rust will eventually come through the filler primer. At least that I what I have been told. The epoxy is better to have as your all over base anyway because it adheres to the old surface better.

[Blazin]

Self etching / rust inhibitive is only for bare metal. Doesn't do anything for the filler or old paint. It won't hurt it to get some on the filler or old paint. Then you can epoxy the whole thing and then urethane the whole thing. Or if you are only doing a touch up / non show finish you can urethane just the repair. Then when you paint you can paint over the primer and the old finish. I don't always epoxy prime. Some self etching primers don't take well to epoxy over them.

[choptop]

I got confused. I thought self-etching primers and epoxy primers were one in the same. I have always used the 2 part epoxy primer (DP-40) but didn't relize there was a different self-etching primer, or maybe thats backwards. Any, now I know to research more. Thanks Blazin

[Blazin]

Self etching primers etch or bite into the steel. Sort of like wood stain does to wood. You can use Dupont 244S to etch any metal. Then use the epoxy primer on it. Dupont Vari Prime is a two part etch primer that works very well, but cost an arm, & a leg. SEM makes a half way decent ready to spray etch primer. Mertin Senior has a two part etch primer that smells and looks very similar to Vari prime. Its called etching filler primer. It actually has a little bit of filling quality to it. The DP 40 is a very good epoxy primer. I am not a big PPG fan but I do like DP 40.

[HAULIN IT]

Blazin' I would like to add, I do have some concern with spraying the etch primer over old paint. I think if you look, most paint companies advise against it (PPG & Sherwin-Williams/NAPA (Trio-prime # 8848 & 8849) for sure. I have seen problems with this, especially with Lacquer,Acrylic Enamel & old factory paint. When the edge of the paint is sanded thin around the fixed spot to feather, that edge is glad to be effected by the strong chemicals in the etch primer. I would like to say "Aim carefully" not to get very much on the old paint. Once that edge is effected by the chemicals the filler primer will lay on there, but not "hold down" the edge from swelling/shrinking later. Just my two cents, Lorne 

[Blazin]

I have read that on a few brands I have used in the past, Mar Hyde was one of them. On the other hand I thought the Mar Hyde etch primer was crap! I have not had any issues with the Martin Senior, or the SEM. But like I said before it is for bare metal

[d stroud]

In my opinion, If you've got epoxy primer, theres really no need for the self etching primer. 

The epoxy will adhere just fine to bare metal without the need to etch it. 

I usually take to bare metal, then epoxy the entire car or panel or what ever I'm working on.  Then, the body work.  I use the 2K primer for building or sometimes spray polyester (slicksand is what I use but others are probably just as good) if the area stills need more fill.  block sand, then block sand, then block sand a few more times.    After that, hit any spots that broke open during the blocking with more epoxy. 

After that cures, hit it one more time with a sealer coat of epoxy primer, then the base and clear.

Also, unless your painting a show truck, I wouldn't get to concern with getting absolutly all of the old "orignal" paint off.  It actually makes a pretty good base for, you guessed it, epoxy primer.

[JJSZABO]

d stroud - that's my process.  I use Southern Polyurathene though (I like it, but a small choice in base colors).

[Blazin]

I don't use polyester primers any more. Back when I first started out my boss was a huge Feather Fill freak. He used it on his 65 GT 350 replica. He wet sanded it, & top coated it. About three months later it developed all kinds of little tiny pinholes all over the car. Dupont rep said that polyester attracts moister. The pin holes where the water coming out through. He said that they had had problems even with high humidity where the work was not wet sanded. Since then I don't use it. Why put something on a car that promotes / attracts water into it.
 I use the self etching because it makes sense to me to have the first coat of material bite into the metal along with the mechanical bond. 
I agree there is no better base than factory paint. I take as little off as possible unless it is a restoration.

[HAULIN IT]

Guys, The polyester primer/filler work great, however you can get in trouble with the moisture thing. The way I look at it is, you need to keep the moisture out. A friend of mine used some on a car, primed in & put it outside under a tarp for a few months. SUPRISE!   He had bubbles & blisters when he took the tarp off. This is a big no-no regardless of what products are on it. Bare metal, body filler, ect. are all bad left uncovered in a humid surrounding. You really should have a de-humidifer  running if your in one of these situations. The polyester products are not really to blame, there is just some precautions to take. Cover it up with epoxy or urethane as soon as possible, especially in damp weather. I prefer the products made by the Clausen co. (Sandy & Rust defender) they can make a good base, quickly (minimal applications) for a excellent finish. You should not be afraid of them, just understand what is happening, Lorne 

[d stroud]

I've been using PPG Epoxy and DBC Base with SPI Clear.  Turns out beautiful.


I've heard a lot of guys really like the SPI Epoxy primer.  I may try it when the PPG primer is gone.

Oh yeah, and I agree about getting any bodywork in primer as soon as possible.  But, thats the beauty of the epoxy primer going down first.  It seals the metal up from moisture, but you do still run the risk of getting moisture in the poly fill.  Though I have never had a problem with it painting out of a home made booth.