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SElf etching primer
#1
I was just wondering if theres any painters out there, would you spray self etching primer over Bondo? Will it still work or what kind of primer do you use over plastic filler and bare metal?
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#2
fs93543;129587 Wrote:I was just wondering if theres any painters out there, would you spray self etching primer over Bondo? Will it still work or what kind of primer do you use over plastic filler and bare metal?
Depends what your doing...If it's a part... say a motor bracket that you smoothed out then self etch would be fine...If it's body panels then I would strip to bare metal..Sand with 80 grit on a d.a.
Then epoxy prime...then filler work ON TOP of the epoxy...seal filler work with epoxy...then 2k primer..
I've been using spi products great stuff..reasonable price...
http://www.southernpolyurethanes.com/

LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#3
(06-12-2013, 05:29 AM)Qcode351mach Wrote:
fs93543;129587 Wrote:I was just wondering if theres any painters out there, would you spray self etching primer over Bondo? Will it still work or what kind of primer do you use over plastic filler and bare metal?
Depends what your doing...If it's a part... say a motor bracket that you smoothed out then self etch would be fine...If it's body panels then I would strip to bare metal..Sand with 80 grit on a d.a.
Then epoxy prime...then filler work ON TOP of the epoxy...seal filler work with epoxy...then 2k primer..
I've been using spi products great stuff..reasonable price...
http://www.southernpolyurethanes.com/

Q knows his stuff. My method is very similar, but a little less conventional, I use an etch primer (P565-597 from PPG's NEXA Autocolor line) followed by 3-4 coats of surfacer (NCP271 corrosion resistant primer by PPG) block out what I can with that, body filler ON TOP of the NCP271, then spray polyester, block, touch up body filler where needed, then more surfacer, final block and finally paint.
To more directly answer your question: etch over filler is ok in small areas but better to stay away from it because it could bleed through and do wierd stuff. The reason behind doing filler over primer is mainly 2 fold,
1. Etch primer or epoxy will always adhere better to bare metal than filler.
2. Filler heats up when it cures from the chemical reaction. If put on cooler metal you actually run the risk of condensation forming between the metal and the plastic as it cures (water+metal=bad)
Hope this helped!

[Image: 2011smallsig_zps31c630dc.png]
"It's what you learn after you know it
all that counts."

-Chip Foose
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#4
It is for my left fender i did all body work filler on the metal already tho... well should i just remove it? or just paint over it?
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#5
No biggie if the body work is already done. Just spray the etch on the bare metal areas avoiding the filler short of some overspray getting on the edges of the filler, then put a few good coats of a 2k surfacer over the whole thing and you should be fine. Epoxy will go direct to metal and can be sprayed with no issues over filler unless you've already got the etch and don't wanna buy another product. A 2k surfacer should be applied over the epoxy too. Either way will surely work. If there's one thing I've learned after being in the auto body industry for about 15 years is that there's usually at least 2-3 ways to do things and get the same result as the next guy.

[Image: 2011smallsig_zps31c630dc.png]
"It's what you learn after you know it
all that counts."

-Chip Foose
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#6
Thanks Obsidian!! One more thing though, What if I just Spray the 2k surfacer over the whole thing without using etching primer. Will it rust out?
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#7
fs93543;130049 Wrote:Thanks Obsidian!! One more thing though, What if I just Spray the 2k surfacer over the whole thing without using etching primer. Will it rust out?
Yes. You must protect bare metal with either epoxy primer or etch primer. If you don't, rust eventually will return or begin anew.

Let me check your shorts!
http://midlifeharness.com

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#8
(06-14-2013, 11:45 AM)fs93543 Wrote: Thanks Obsidian!! One more thing though, What if I just Spray the 2k surfacer over the whole thing without using etching primer. Will it rust out?

Yes, etch or epoxy is definitely needed. Surfacer isn't designed (typically) to go direct to metal. Few will do a decent job, but it's always best to go with an etch or epoxy 1st. Surfacer is designed to be able to block out minor flaws before paint, not corrosion protection.

[Image: 2011smallsig_zps31c630dc.png]
"It's what you learn after you know it
all that counts."

-Chip Foose
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#9
I forgot to mention: after etch primer, you'll need to apply a sealer. Epoxy does the job of both.

Let me check your shorts!
http://midlifeharness.com

[Image: Flamicon2.jpg]


[Image: oldfart.png]
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#10
(06-14-2013, 08:37 PM)midlife Wrote: I forgot to mention: after etch primer, you'll need to apply a sealer. Epoxy does the job of both.

True, I go etch to surfacer, a lot of guys go epoxy because it saves a step. I go to surfacer because it has more build to get my blocking started and help me find my highs and lows.

[Image: 2011smallsig_zps31c630dc.png]
"It's what you learn after you know it
all that counts."

-Chip Foose
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