Mud over primer, can I do it?

I am at the point of needing to smooth a few things on my chassis. It is covered in a nice coat of self etching primer. Can I start skimming a few areas with some sort of filler and be OK or does it need to be stripped in those areas. also could some one suggest a brand and type of filler to buy. This is an A chassis for a channeled car, I am only real worried about from the cowl forward. Thanks in advace for the advice.

 

No you dont need to strip the primer just scuff it with 120 and mud away

 

That's what I like to hear. Any suggestions on what to buy.

 

I use a 3M product called Piranha Putty...this may be a little overkill (and expensive) for a frame job but that would be your call.

 

You can, but should you? . . . NO! Don't mud over anything but raw, clean metal that has been roughed with AT LEAST 80g by DA or grinder for proper adhesion. However, it is acceptable to apply half-time or another pin-hole filler over either acid-etch or any other suitable primer. Evercoat, the fiberglass folks, they make great fillers of all kinds. Deal with a reputible automotive paint supplier.

Of course, this is all very optional.

 

Incidently, I too drive a flathead 29-A 2dr sedan (with absolutely no paint at all). But, . . . I am in the biz and hold an international award for paint and graphics from DuPont.

 

Absolutely. In fact you will get a finer feathered edge working on top of scuffed primer. Some fillers will recommend it BTW.

As for filler, I am useing a new one (for me that is) Evercoat filler #3. True it dosen't clog the paper as bad, but man this stuff is a pain to work and even harder to spread. I will go back to Feather Lite in the gray and purple can.

But for a frame I would just drop by the local parts whore and get some Bondo brand in a smaller can.

 

can we see pictures ...of the car (not the award)? and maybe an intro, so we know who you are?

 

This is one of those questions you will get both answers for. Both are acceptable from what I have learned. I prefer to use epoxy primer first and then filler. Either method should work fine. Evercoats Rage Gold or I think the new one is Rage Extreme are very good fillers, easy to work with. Just my .02

Bill

 

True enough, opinions vary on this subject. Self etching primers come in many varieties. So it really depends on what you've used.

The main problem with fillers over primers is that all of these products have a solvent base to them of some kind. Depending on the type and mil thickness of the primer, the filler's solvents sometimes can soften the primer underneath. It never shows up until the final top coat is applied...then it shows up as a dreaded "bullseye" in your finish. There will be a crazing or lifting "ring" around the repair.

In general as stated above, you can apply over most any fully cured epoxy based primer. Some self etching primers (most) have an acid base to them...etches the metal. At that point they're applied in very thin and transparent coats and pose no threat.

As for fillers, the tried and true Kromate Light is very hard to beat in both price and quality. Rage does do what it says, but I can buy 2 Kromates for the price of 1 Rage. In the end, it's all some type of fuckin "bondo" and most of them are the same. For real easy sanding and small work, USC "Icing" or Evercoat "Metal Glaze" do a fine job. The whole secret to using fillers is to sand it at the right time and use as little as possible. What's the right time? Kromate likes 30-60min, Metal Glaze likes 15min. Any longer and you work yer ass of getting a nice finish. I hope this was helpful.

 

I really like the Icing. easy to sand, and it goes right over primer. it was originally supposed to be a pin hole filler, but it works great for MINOR,SHALLOW fills as well.
Keep it thin and it kicks ass. I have never had a problem with bullseyes or peroxide bleaching with it.
Good Luck!

 

I use Zero Rust Red Oxide on frames and sheet metal and then Evercoat Rage over as needed. I then topcoat with ZR Black on frames or a top coat compatible primer.
ZR is chemically compatible with most plastic fillers.

www.zerorust.com

A bad thing about mud over bare metal is that it will allow moisture to get under it over time and start lifting. Maybe not a problem in the Southwest but a big problem out here. The ZR will seal the metal from the air and moisture.

 

I got a can of "Black Magic" from '62...used it to fill holes in a de-chrome job...is it still good to use? on my trophy?

 

I've used a topstop before and that recommends going on over paint, it is a filler type not a cellulose base one. Do you guys have Upol brand filler there?

 

Who cares?

But yes you can mud over primer, as a matter of fact most of the top guys around here do it over an epoxy like dp90....