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-   -   I bought Dupont products to paint rusted car parts, but I feel like I'm wrong... (http://www.hotrodders.com/forum/i-bought-dupont-products-paint-rusted-car-parts-but-i-166280.html)

klingfilm 10-06-2009 07:31 PM

I bought etch primer to fix my paint, but I feel like changing for epoxy primer...
 
Hi,
Here is my problem, I have a cavalier 05 orange sunburst II and some flakes of paint went off after an accident revealing rust just at the end of the fender beside the headlamp. I hit a little dear...It is sad, but it is not the point.
So, the insurance didn't fix it and I have to do something with it. I tried the spray cans, but what a disaster with the clearcoat!
One thing I know is that I'll have to sand block the rusted part and use something like BONDO (3M filler) to flatten the bare metal with the chipped paint.

So I started my journey at a NAPA shop. The guy sold me
Dupont Nason 497-00 urethane clearcoat
Dupont Nason 483-78 activator

Dupont ChromaBase base coat -Orange Sunburst II
Dupont Chroma System Basemaker 7175S Mid temp

Dupont Etch Primer 1k A-4115S

But my question is about the layers in between Etch primer and base coat.
Can I put bondo over etch primer and would they stick together?
And what should I put between Bondo and base coat ?

I don't feel like the sandwich

Bare metal
Etch primer
Bondo
Base coat
Clearcoat

is going to work well...
I need help.

i1964ss 10-06-2009 09:16 PM

dupont products
 
hi, well you din't mention how big the damage is, sometimes is better get a new part than try to fix the one, however if you gonna put bondo you have to grind first the dent (make sure all the rust is gone) then apply the bondo, the etch primer use it only if there's big surface of bare metal if that's not the case use 2k primer right after the bondo dupont products are good the clear is not the best dupont has to offer but work just fine

Centerline 10-06-2009 09:48 PM

Here is what I would do.

Grind all the rust off then shoot the etch primer over the bare metal. When its dry rough it up with some 80 grit and then apply the bondo. After you have the surface shape the way you want spray some high build 2K primer. Wet sand with 400 grit then 600 to get the surface nice and smooth. Now your ready for your base and clear coats.

Many people don't mind putting bondo over bare metal, that's pretty much old school but....... bondo sticks very well to roughed up etch primer and the primer will help seal the metal from any moisture that might get through the bondo before it is painted. Bondo is very porous and wet sanding and even high humidity will allow dampness to get through and begin rusting the bare metal again. Using the etch primer first eliminates that problem.

klingfilm 10-06-2009 09:51 PM

I'm quite impress! It's faster to get support here than at any Canadian Tire.
The damage done to my car is pretty small I think. It is not bigger than a thumb and the rust is still a the surface on the metal.
So, I won't have to grind it, I'll just use a sand block.
About the clear coat, I know it is not the best stuff but my cavalier will never do any expo show.
I only want to remove rust first, and then have uniform color with a proper finish. I just hate to see rust it's a real pain when you deal with hard winters.

So, If I get it right I should go back to the shop and buy a high build 2k primer. Also, the 3M bondo will stick to the etch primer.

P.S. Can you tell me the meaning of "1k" and "2k"? And what is high build?

klingfilm 10-07-2009 06:48 AM

how about no etch primer and epoxy primer instead?
 
Hi,
I've been reading about bondo and etch primer, and top coats. Bondo over etch primer could be a problem especially if you don't let it cure long enough to get rid of the acid.
But, with that product, I have to buy a 2k high build primer.
After hours of reading through Dupont technical manuals, I have another Idea and I need your opinion on it.

My idea is to return the etch primer and buy instead
Dupont DTM epoxy primer 25x0S.
This product can stick to the metal and protect it.
It sticks to bondo too.
And I can use my ChromaBase over it

So my new sandwich would be,
DTM epoxy primer over the sanded metal
Bondo over it to obtain a plain surface with the chips of paint missing
DTM epoxy primer again to offer a proper substrate to my basecoat
Basecoat
Clear coat

What do you think? Am I improving with my reading or am I getting worse? :P

cyclopsblown34 10-07-2009 08:13 AM

You're on the right track. I'd still use a surfacer/hi build urethane 2K (2 component primer) to fill any pinholes and whatnot. Other than adding the high build primer, you're on the right track. Spray the entire panel with it and make it your coat between the bondo and epoxy before paint. You definitely want to start with the epoxy on bare metal.
DTM Epoxy
Filler/Bondo
2K hi build primer
DTM Epoxy
Color
Clear.

deadbodyman 10-07-2009 08:23 AM

Bondo will NOT stick to etching primer,it will stick to epoxy primer,but niether are nessary for such a car just grind, bondo, prime with 2k sand and paint

Centerline 10-07-2009 09:46 AM

Quote:

Originally Posted by deadbodyman
Bondo will NOT stick to etching primer,it will stick to epoxy primer,but niether are nessary for such a car just grind, bondo, prime with 2k sand and paint

Sorry but you are dead wrong! Bondo sticks very well to etch primer providing its dry and roughed with something like 80 grit. Although it is yesterday's technology it still works very well. Epoxy is really the way to go but since the poster already had the etch I saw no reason to tell him to return it. Especially considering it was a very small job.

Also, the spell check button is there for a reason (it makes your posts more easily readable), please feel free to use it.

klingfilm 10-07-2009 10:43 AM

First,
Sorry about the roughness of my words and spelling. But as a French canadian, I am about as good as a 13 years old average student, expecially when it's time to write.
Could you help me to understand the need for 2k primer? I thought it is mainly useful to sand the surface quicker than the epoxy primer to get a nice smooth finish prior to basecoat. But, the metallic area that I have to cover is small about the size of a match box. So I don't mind having to sand 30 min more over my epoxy primer just to get the same finish as I would get in 5 min with 2K primer.
I have sand papers with grid from 60 to 2000. I just feel like it's useless to buy a full can of 2k primer and epoxy primer on such a small area that needs bondo.
I plan to repaint the hole fender, but I'll just sand the clearcoat from it and paint over the original basecoat.
Can you show me your sandwich?

cyclopsblown34 10-07-2009 11:03 AM

I've been told by my DuPont rep that any epoxy primer requires at the finest 80 grit scratches to bite to. Any finer and it is relying on the tension of itself to hold it to the panel.

klingfilm 10-07-2009 11:15 AM

Hum...This is a really helpful comment from you cyclopsblown. But frustrating at the same time.
Let me resume, If I use epoxy primer as a layer under my base coat, I must not sand it with a grid finer than 80 grid because my base coat will not really stick to it.

So, I have to put 2k high build primer over it anyway to be able to gain a smooth finish for my base coat.

Whatever I do, I must buy a 2k primer to put in between the bondo and the base coat.

This might be my last question. Which Dupont 2k primer would be compatible to stick to bondo and ChromaBase base coat?

cyclopsblown34 10-07-2009 11:26 AM

The sanding scratches the epoxy covers can be no finer than 80 grit. As for 2K primer, ask the supplier for some Nason 2K primer. They offer a 4:1 mix I think and it is a high build polyester or Urethane, I can't remember which. They should be able to supply you a one quart kit and the same quantity on paint and clear. That is unless they already mixed the color as a larger quantity.

As for sanding the epoxy, I usually let it dry a couple days if I'm going to sand it and then only gently so it doesn't gum the paper. i usually don't sand the epoxy, I try to get the 2K primer on it while it is still "open", that way the 2K primer sticks by chemical reaction.

cyclopsblown34 10-07-2009 11:30 AM

To use an old cliche', There's more than one way to skin a cat. Deadbodyman is way more knowledgeable than I am about body and paint work.

klingfilm 10-07-2009 11:36 AM

I am finally focusing toward a complete solution. I need 2k primer anyway. But, I see many types of 2k primer from Dupont.
I can get:

-Primer-Filler
-Primer-Sealer
-Urethane primer-filler

What should I use between my bondo and ChromaBase?

cyclopsblown34 10-07-2009 11:47 AM

Urethane primer is my preference. I use sealer as my last coat before color. Several people say sealer is unnecessary but it is my security blanket.


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