Reprimer questions

[austin552]

My 911s PO primed it with an etching primer many years ago. The primer has worn thin and small surface rust has appeared. The rust doesn't look too bad, just minor pitting in some areas.

Can I sand down the pitted areas and reprime the whole car with a filler primer?
How can I use rust converter to help?
What grit papers should I use durring the process?

Thanks,
Austin

[Cdnone1]

Anyone have any suggestions. I'm in the same situation

Steve

[Fast Corners]

Originally Posted by austin552

Can I sand down the pitted areas and reprime the whole car with a filler primer?
How can I use rust converter to help?
What grit papers should I use durring the process?

I'm not sure I get this, is the entire car in primer? Assuming that it is, it depends on how deep the pitting is as to wheather or not a filler primer will work out for you. 320 Grit is a good general use paper that still has good cutting action and will prep the surface for primer well. Once you get down to the metal use some "metal prep" as it will help out. Use a wax and grease remover and prime it. Once it is primed get some real paint on it. Primer is pourous and will not protect the underlying metal from moisture.

[austin552]

Yes, the whole car is primer however only certain spots have pitting. I guess I can just sand these areas to the metal and use the converter to help. Then reprime the whole car with filler primer.

Thanks,
Austin

[962porsche]

from what you have told us . i would sand the hole car down removing all the old primer . just to see what was under it . primers do not stop water penetration at all .in time moisture will get at the bare metal . if i find rust . and it needs to be sand blasted i do so . or if i can sand it out i do so . then using an E-type primer i prime over the bare metal only . then with a ( filler primer ) prime over the E-primer and the sanded piant on the panel .

[lindemans]

Etching primers (also called washprimers) need to be covered with the next layer (filler) within 24 hours. If you wait longer you may get bonding problems.

If the primer has been on it longer, as in this case, it needs to be sanded again anyway, then again thin layer of washprimer and then filler etc.
Please note that epoxy-based materials (like epoxyfiller) do not bond well on washprimers; use a filler that is suitable for washprimers. I always like to refer to the tech data sheets of the manufacturers.
To be sure you have no hidden rust left, I would indeed sand the entire body to bare metal again.
I like the etching primers for its enormous bonding to the metal, but you could also start with epoxy primer alternatively; you're more flexibel as to what you can spray over epoxy as basis.

If you have rust on the surface, sand it to shining steel; if you still see dark pitting, that needs to be removed too.
I usually take a dremel-like tool to grind that out.

This rustconverter stuff is the last option I would move to: getting to bare metal is always better.

[austin552]

Thanks guys! Looks like I have my work cut out for me.