[tech69]

I watched a video where a guy said no real shops use epoxy. I was taught epoxy was the way to go but I'm open to differing opinions. Would love to hear thoughts from guys who've been doing it a lot longer than me.

[cyclopsblown34]

If you're not teaching...you're learning. Man, you're gonna be the next Martinsr. I learned etch was the way to go when Centari was top end. Since I started with urethanes, I use epoxy.

[skip99]

never have used etch,,, back in ....83? I was using lacquer as a base, striping up everthing, and adding "confetti " remember that? lol!
and spraying clear Imron... about 88 went to work at a ford dealership doing nothing but spraying all the trucks that were losing their paint, must have done about 300...thats when I started using epoxy and ppg mostly..dp epoxy,
used it up til about 3-4 years ago and then dplf...finally quit that stuff and use omni now, but about to order some SPI..hope it lives up to the hype..I really dont think these guys will steer you wrong. ..

[DanielC]

I am going to suggest the main consideration in "real shops" is to beat a flat rate, and get it out the door. A job that last longer than the next time the car is sold is good enough.

Getting back to the question, epoxy VS etch.
Read the Data sheet for the products you use. DPLF Data sheet has this sentence in the preparation section.
"Chemical treatment or the use of a conversion coating will enhance the adhesion and performance properties of the finished system."

If you switch to another epoxy produce, read it's data sheet

[tech69]

Originally Posted by DanielC

I am going to suggest the main consideration in "real shops" is to beat a flat rate, and get it out the door. A job that last longer than the next time the car is sold is good enough.

Getting back to the question, epoxy VS etch.
Read the Data sheet for the products you use. DPLF Data sheet has this sentence in the preparation section.
"Chemical treatment or the use of a conversion coating will enhance the adhesion and performance properties of the finished system."

If you switch to another epoxy produce, read it's data sheet

I get a little of that from the boss but I also know the best cars out there come from a shop, or from sidework from one of the workers.

[35prog]

There are trade offs, on each. Epoxy is by far the best for corrosion resistance and will promote adhesion like crazy. But it is slower, requires time to dry before topcoat with anything. Etch prime is much faster and will promote adhesion on bare metal. If the entire panel is bare I would epoxy. For small bare metal spots I often use epoxy as well, but not always. If speed is not the main issue use epoxy. I use only SPI epoxies. Also will tell you that some auto manufactures are stating use of epoxies in repairs to meet warranty requirements. For a driver quality job or on a lower cost (AKA quality) job use etch. If quality is main concern use epoxy period.

[WriterDennis]

From my experience, etch primer will allow a new paint job to look ok for awhile, but will not provide much corrosion resistance. On the other hand, epoxy primer, especially the PPG DP line (I don't work for PPG, but I will say I like their products) give great corrosion resistance and provides superior adhesion. I would always suggest using an epoxy primer, then filler primer when block sanding, followed by a sealer, then color and clear (optional).

Dennis W. Parks
Author of How to Paint Your Car

[tech69]

thanks for the input. From what I gather is epoxy is the most dense(best barrier coat), has one of the best grips on metal, and is compatible with paints and even makes paint stick better when using it as a sealer.

Etch on the other hand has acid which etches into metal, does protect metal well, kills small flash rust, adheres better to metal and doesn't need as much mechanical scratch as epoxy does, but the acid in the etch can cause adhesion issues.

Is this pretty accurate?

So I gotta ask, what's the biggest reason you don't use etch/epoxy?

Most shops I know use epoxy and very little etch. Ca isn't exactly the rust belt though.

[Lizer]

Originally Posted by tech69

thanks for the input. From what I gather is epoxy is the most dense(best barrier coat), has one of the best grips on metal, and is compatible with paints and even makes paint stick better when using it as a sealer.

Etch on the other hand has acid which etches into metal, does protect metal well, kills small flash rust, adheres better to metal and doesn't need as much mechanical scratch as epoxy does, but the acid in the etch can cause adhesion issues.

Is this pretty accurate?

So I gotta ask, what's the biggest reason you don't use etch/epoxy?

Most shops I know use epoxy and very little etch. Ca isn't exactly the rust belt though.

Epoxy (at least SPI) is zinc phosphate-based. Zinc phosphate essentially does the same things as an acid etcher: it also etches metal and kills and inhibits rust and corrosion.

I will say this: I had some panels on my Mustang in Sikkens 1k wash primer, leaving them only in the etching primer without any additional top coat for awhile. The idea was to keep the panels from flashing, but they still did begin rusting with the etch. I suppose that shouldn't be too surprising.

What should be more surprising is the amount of rust I've experienced still breaking through my epoxy, or rust I've found beneath epoxy that I've sanded off. This is nice clean, DA metal I'm spraying here.

[OneMoreTime]

I have had no issues with rust using epoxy..My procedure now is to clean the parts and epoxy them and put them on the shelf and when I need them then install them and then do the finish painting but then this is a fabrication and hot rod shop and parts have a tendency to stay on the shelf for an extended period of time until they are needed in the build..

Sam

[Lizer]

That's essentially I do too. Most of my car or parts have been sitting in epoxy for about 2 years now.

[hoffmandirt]

What kind of prep work do you have to do to the epoxied panels that sat for an extended period of time before you decide to use them?

[OneMoreTime]

All I do is scuff the part and wipe the dust off with W&G remover (the water base kind) and paint away..Some things I do not bother like trailer hitches and chassis parts, just bolt those on and run em..

Sam

[Lizer]

Pretty much. I scuff it with a worn piece of 220 folded up in my hand, then degrease.