E-Coating on replacement panels
 

First, I want to apologize if there is already a thread on this topic. I used the search function but didn't see one, maybe I scanned over it. If one already exists, feel free to slam me, or merge/delete this, Mods. :) Just let me know where to find it first!

OK, so I received a replacement rear fender from LMC Truck, and it has that black primer e-coating (?) on it. My plan is to finish the fender in PPG D74LF primer to match the rest of my truck (refer to my avatar). So my question is: how should I prep the fender before applying the PPG primer? Do I need to sand off the e-coating? Just scuff it up and shoot the PPG primer? Actually, now that I think about it, I have no idea what that black coating is! Anyone know what they use on their fenders? If not, I'll call and ask them.

Thanks in advance, and again, if there's already a thread on this, please post a linky dink for me?

Ant

I would contact LMC truck. Post back what they tell you, I might be getting some LMC panels in the future.

"PPG D74LF" Is this a misprint? Did you mean PPG DP74LF, with actvator?

I have the PPG data sheet on DPLF. and you should too.

If you cannot find out what is on the panel, I would sand it to bare metal, and then prime it with the DP74LF. Optional, use the DX1791/DX1792 wash primer, under the DPLF.

Wipe a rag soaked in lacquer thinner on it. If it lifts the black primer then strip it off. I have had floor pans that the primer lifted. If not just sand and refinish.

Daniel, yes activated DP74LF. Thanks for catching my mis-print.

Update: I spoke with a customer rep at LMC, they say it's an "EDP" coating, and intended to be left on, just clean it, scuff and shoot the finish coats onto it. To be safe, I'll test it with the lacquer thinner as suggested here first. If it lifts or otherwise comes off, I'll take it down to bare metal. If not, scuff and shoot.....I guess.

I use aftermarket parts all the time. just clean with wax and grease remover, sand ,seal and paint according to paint mfg directions. This coating is said to contain rust inhibitors and shouldn't be removed. If it is removed a self etching primer should be used on bare metal.

Yep, go ahead and scuff and shoot. The EDP is high in zinc and
protects the metal underneath from oxidizing/rusting.

I have faith in the factory e-coat that I'll just sand good and prime and paint. The after market stuff especially the crap from overseas I don't trust. That I'll sand to metal, a coat of spi epoxy ,and go from there.

Funny you should post that question. I just got certified for waterbourne paint two months ago and that was part of the test.

First, never trust what a supplier or manufacturer tells you, yeah, that was on the test.

Use thinner on a piece of rag only, not wax or grease remover or mineral spirits, just thinner. If it’s soluble or lifts then you must remove coating. Also, take a piece duct tape and firmly adhere it to the panel then rip it off. If the coating lifts with the tape then remove coating. Those are the proper methods to use to determine if the coating should be removed.

And if you apply PPG DPLF you can also try the lacquer soaked rag on it, but be prepared to substitute something better and cheaper like SPI when it wipes right off :pain: .

Vince

X2. Exact same thing I've heard from several people who have used it.

I would not assume the panels from LMC truck are made in the USA, unless told otherwise.

"And if you apply PPG DPLF you can also try the lacquer soaked rag on it, but be prepared to substitute something better and cheaper like SPI when it wipes right off ."

PPG DPLF is a base coat. It is intended to be topcoated with a paint. I do not normally park my cars, when they are in primer only, were it rains lacquer thinner. I would also think that if the undercoat gets softened by the solvents in a topcoat, that would only help the bond between the primer, and the paint.

DPLF is epoxy primer not a basecoat. The problem is, if you can wipe epoxy primer, or any primer for that matter, off with lacquer thinner it has not bonded to the metal. And THERE lies the problem.

You are right, DPLF is a primer. I stand corrected on that.
My point still stands. A primer is not designed to protect against degradation by strong solvents. That is what the top coat does. Even then, I would suggest rubbing almost any paint with a strong solvent like lacquer thinner will cause some degradation, unless the paint was designed to pass this "snake oil barker at a county fair trick"
The reality is that in many cities you cannot even use lacquer thinner anymore because of excessive VOC problems.
Saying a primer will not resist degradation by a strong solvent is like saying it will not hold up to sandblasting. In both cases you are doing something to the coating it was not designed to resist.

Does SPI advertise on this board? Are they a supporter of this forum? Sometimes I wonder if somebody somewhere is getting a benefit by constantly pushing this product line.

PPG is pushed on this board alot more than most other brands. Do you think that they get a kick back?