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Epoxy vs. Self Etch for inside quarter panels...

4K views 30 replies 9 participants last post by  Sauron67MM 
#1 ·
I am replacing both full quarters on my 68 body tub. When I took off the quarter panels, there is all kinds of surface rust underneath.

My plan is to media blast, sand, grind, or do whatever I can to get the surface rust out on the area underneath the quarters (the top of the outer wheel well, and so on) down to the bare metal, and then to seal it in or coat it.

Obviously nobody will ever see this area. So once I blast it out, what do I coat it with?

Should I do an epoxy or a self etch? Should I put a rust proofing enamel over it?
 
#2 ·
Epoxy all the way. Etch primer is old school and really has no place now that quality epoxies are available and far superior to etch primer.

Don
 
#4 ·
Test it with lacquer thinner to make sure it really is EDP. I just scuff it and shoot with epoxy on internal surfaces but I sand if off on the large exterior surfaces before epoxy.

Don
 
#7 ·
Some epoxies will fail if applied over etch primer and there reallly is no reason or advantage to etch before epoxy.

Don
 
#11 ·
Just don't apply the first coat too heavy or it will crater on you. Second coat can go on wet and will have a nice gloss.

Don
 
#12 ·
Hey Don
You have replied to a few of my posts and I took auto refinishing and have painted about 6 cars , We were taught to give the entire car a light tac coat as you said and then spray it wet. I am always looking for any advice and helpful tip. Have you tried the Southern Poly paint ?
 
#14 ·
Now that we are off the epoxy topic. Follow the TDS for topcoat application, or any other product for that matter. Tack coats were used in the older enamel days. You will commonly see a tech sheet state to apply 2-3 wet coats. Which means apply the first just as you apply the last. Quality of paint determines DOI ( Distinctness of Image), or deep wet look as you require.

Epoxy over etch is not recommended by companies and only if a certain etch primer is used. Epoxy over properly prepared metal is more than adequate.
 
#16 ·
Don
I understand what you are talking about and will spray the tac coat. The IWATA HVLP gun you suggested is right at $400 on ebay and I was looking at the DeVilbiss GTI 620 Millennium for a little less do you have a option on that ? How does the SPI compare to PPG as far as the quality ? There are a lot of good reviews about it and the cost is quite a bit less. By the way this is for my 67 RS/SS350 I took it all to metal and what I didn"t like I replaced which was quite a bit but OER seems to make a good product at a fair price and I was able to get rid of a lot of bondo. Thanks in advance for the help Don
 
#18 ·
Hi Tom. I haven't used the Devilbiss but the Iwata atomizes so well that it is a great gun to use. You can always sell it for good money when you are done which you can't say for the Devilbiss. I am sure you will not be disappointed. I just had this same discussion with a local guy and he is now raving about the paint he laid down with his new Iwata. :smile2:

I have been using the SPI epoxy for several years and previously used PPG. I prefer the SPI and PPG is insanely priced at my local jobber. I also use SPI turbo primer, basecoat, single stage and universal clear. SPI red and black are amazing colors if you don't care about a factory match. I still use PPG basecoats from time to time.

Don
 
#17 ·
SPI epoxy is good to use on the inside panels and back side of fenders. I used it on my 67 Camaro after I sanded all the EDP off. I hate that stuff, all it does is cause a lot more work. The guy that painted my car worked for a Chevy dealer in Richmond, Va. I gave him a gallon of the SPI epoxy to use. He never heard of it before and told me it was thick like paint. I sprayed the roof on my Camaro with SPI epoxy after stripping it. I thought it went on really good.
 
#19 ·
I stock and use numerous epoxies, SPI being just one. SPI shot at 1:1 can result in excessive mil thickness. Epoxy on bare metal prior to filler is for corrosion protection only, and not to be used as a high build primer as many do. I have received cars that had SPI epoxy hammered on before filler work for no reason. The same unnecessary mil thickness can be done with any epoxy or primer. Qualified restoration shops that I know who use SPI epoxy exclusively do not shoot it at 1:1 reduction, and do not pour it on.

Little mention of PPG commercial epoxy and primer line on these sites. PPG CRE epoxy is an excellent product. Speak with your jobber if they have a commercial contract. Call the company tech line or set up an appointment with a rep. All contact info is available on their websites. Or try a site like this where the pros hang out and can refer you to other pros: https://www.facebook.com/groups/890041547687300/
 
#21 ·
Hi Tom. I am not a painter, just a retired engineer building cars out in my shop. :smile2: I build for myself and also for a few customers along the way. Not SEMA show quality but nice clean drivers that regular folks can afford and enjoy.

Scott is the resident painter expert. He knows a lot more than the likes of me... :smile2:

That is the gun you want with the silver cap and 1.4 tip. I use mine to shoot base and clear. I also have a couple of Sata guns I use for clear. A 3000RP and 5000RP if I remember right.

As far as hammering on the epoxy I thought we were talking about the back side of panels and not prepping panels for filler... :smile2:

Don
 
#23 ·
The Iwata can be used for base, clear and shooting reduced epoxy. I shoot non reduced epoxy with a primer gun and a 1.8 tip. I only reduce epoxy when using it as a sealer before basecoat. Otherwise I do not reduce it. SPI does not recommend reducing except when using it as a sealer.

Don
 
#24 ·
Scottt,
What % reduction do you recommend for the SPI? I've only used it once and it was on a new piece of farm equipment I built. I felt it was excessively thick at 1:1 (might have reduced it a bit per the TDS I don't remember). I p minute induction was lame as well. It didn't matter given the application but I remember not wanting it to use it for an auto application. And I haven't . Moved to shopline but still have a 1/2 gallon of SPI I'd like to work through.
 
#26 ·
If it too thick skip the induction time. The only reason they specify induction is to thicken it up for newbies that will have trouble if it is too thin. Straight from Barry at SPI....

Don
 
#27 ·
Hi Tom. Let us know if you go with the Iwata and how you like it.

Don
 
#28 ·
So here's a follow up question. Once I sand down/media blast the under parts of panels (right now I am taking of a couple of rusted cowl boxes) and get in the nooks and crannies I was hoping to use picklex 20. Can I shoot epoxy over picklex 20?

Thanks again!
 
#29 ·
Not SPI epoxy. Check their website for the tech manual.

Don
 
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