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  #1  
Old 01-29-2010, 01:14 PM
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jferraro17 jferraro17 is offline
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Default Priming 2 different materials

So, I've reached the point with the emp tips that I'm happy with the finish--at least I think I am.

I would like to coat these areas with primer since a final paint job is years down the road. Any suggestions on what to use? My concern is, the combination of fiberglass and aluminum in the areas that need to be coated. I'm pretty sure I can't use the self-etching rattle cans I've been using throughout the build for parts.

Thanks for any advice.

Joe
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Last edited by jferraro17 : 01-29-2010 at 01:39 PM.
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  #2  
Old 01-29-2010, 01:19 PM
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I'm also at this point and dont have an answer yet how I'm going to do it so I'll be interested to see what the concensus is?
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  #3  
Old 01-29-2010, 01:36 PM
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I am "all ears" on this one too. My plan was to use regular (non-etching) primer on the fiberglass. However, I have a couple cans of self-etching left that I wouldn't mind using up.
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  #4  
Old 01-29-2010, 02:09 PM
Ted Johns Ted Johns is offline
 
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If it was me, I'd use an epoxy primer like PPG DP40 or similar. Don't go wild with the amount of coverage, because down the road you will have to scuff it all with red scotchbright and give it another DP40 coat prior to the finish coats.

Most epoxy primers have only a day to a week of "open" time before the above requirement kicks in. When the primer coat is too old, the top coats don't chemically bond to it, and peeling may happen.
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  #5  
Old 01-29-2010, 02:43 PM
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http://smartshoppersinc.com/Kirker/primers.html

Kirker Enduro prime. Etching primer, works on both aluminum and fiberglass, and is inexpensive. I've used it and really like it, lays down smooth. Equivalent to PPG DP40LF. You can get two gallons sprayable for the price of two quarts of PPG.
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  #6  
Old 01-29-2010, 02:43 PM
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Quote:
Originally Posted by Ted Johns View Post
If it was me, I'd use an epoxy primer like PPG DP40 or similar.
Epoxy primer on both alum and fiberglass? Acid etch alum first?

What about filler primer for the tips? Would that go on over the epoxy primer?
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  #7  
Old 01-29-2010, 03:47 PM
Ted Johns Ted Johns is offline
 
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Quote:
Originally Posted by RV7Ron View Post
Epoxy primer on both alum and fiberglass? Acid etch alum first?

What about filler primer for the tips? Would that go on over the epoxy primer?
I don't like the idea of acid etch sitting in between built up layers, so I'd reserve it for individual parts. Built up parts I'd carefully solvent wipe and then scotchbright etch. If the parts are already alodined, solvent wipe and shoot primer.

I don't like the idea of etch primer on fiberglass, though some mfg's may be ok with it.

Fiberglass: Fill pinholes first (resin wipe or wonderfil, or ...), then epoxy prime, them filler primer as needed. If you're going to give it a full coat of urethane filler primer, and not sand through it, then no need for the epoxy primer. The main advantage to a epoxy primer under a filler primer is that you immediately see when you've sanded through, and the epoxy is a bit tougher to sand through.

PPG's optimum plan for aluminum is a thin coat of acid etch, followed by a coat of epoxy primer. Many of their topcoats are not recommended for direct application over DX1791 (their chromate based etch primer). The DX1791 largely replaces alodining by providing some chromate based corrosion protection. Yup, it turns the metal a nice light gold color. If you don't need the extra bit of corrosion protection, epoxy straight to prepped aluminum is fine.
People have been successful shooting PPG Concept straight over DX1791, but when in doubt, follow the p-sheets, that's what I say.
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