Etching before paint |
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Etching before paint |
worn |
Mar 4 2023, 05:12 PM
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#1
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can't remember Group: Members Posts: 3,156 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
Looking for advice. The car is at bare metal and the next step is epoxy sealer followed by k36 sandable primer etc. i have used a variety of phosphoric acid concoctions to turn pits or crevices to black iron II. But on sanded bare steel it leaves a grey haze at best, and a slightly orange have at worst. I am not a friend of iron oxide under my paint.
With all of that said, i know that a lot of folks etch prior to paint. In my hands that hazy stuff makes me nervous. Will it adhere as tightly to the paint and steel as the epoxy would without the etching. My chemistry knowledge is stronger when you have a bunch of carbons to play with. So any help would be appreciated. |
Superhawk996 |
Mar 4 2023, 05:54 PM
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#2
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914 Guru Group: Members Posts: 5,836 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
I’m Confused.
If at bare metal - sealer is not the first thing to go down under primer onto metal. Maybe I’m misunderstanding what you meant? Regarding etch. Properly done, etch will be slightly gray - no longer shiny metal. Should not be rust or orange. Trick to etch is do only a small area. Etch, rinse, dry immediately. If you can’t master that - start with shiny bare metal and source a self etching primer. Edit: not pointing fingers at you - high humidity or other corrosives in your shop can cause the flash rust / orange haze. Sealer goes between primer and topcoat for PPG systems I’ve used. |
Superhawk996 |
Mar 4 2023, 06:00 PM
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#3
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914 Guru Group: Members Posts: 5,836 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
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FL000 |
Mar 4 2023, 06:20 PM
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#4
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Member Group: Members Posts: 395 Joined: 31-January 12 From: Lancaster, CA Member No.: 14,076 Region Association: Southern California |
If you have a local paint shop I recommend buying your products through them (if doing it all yourself). They’ll be able to sell you compatible items, and give you some good advice. I did that when I painted my car and haven’t had any weird issues.
And agree, scour the tech sheets. |
930cabman |
Mar 4 2023, 06:35 PM
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#5
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Advanced Member Group: Members Posts: 3,071 Joined: 12-November 20 From: Buffalo Member No.: 24,877 Region Association: North East States |
If you have a local paint shop I recommend buying your products through them (if doing it all yourself). They’ll be able to sell you compatible items, and give you some good advice. I did that when I painted my car and haven’t had any weird issues. And agree, scour the tech sheets. (IMG:style_emoticons/default/agree.gif) It's a system that needs to work together. |
Front yard mechanic |
Mar 4 2023, 06:49 PM
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#6
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Senior Member Group: Members Posts: 1,165 Joined: 23-July 15 From: New Mexico Member No.: 18,984 Region Association: None |
Use this stuff it sticks like no tomorrow you can 60 grit your deep dents and bondo or lighter for top coat filler and any primer will adhere well
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worn |
Mar 5 2023, 03:14 AM
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#7
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can't remember Group: Members Posts: 3,156 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
DP40 and DP402LF is the first thing to go on the steel. I am very fond of PPG epoxy. PPG thinks that is perfectly ok under K36. But I misspoke. It does seal metal from moisture, but isn’t a color sealer. Do you think because I am *not* using an etching primer that I should use a metal etch? |
mb911 |
Mar 5 2023, 06:59 AM
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#8
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914 Guru Group: Members Posts: 6,854 Joined: 2-January 09 From: Burlington wi Member No.: 9,892 Region Association: Upper MidWest |
You can use epoxy over freshly sanded and cleaned metal. You then do primer surfacer or any body filler over that then seal and paint(I use epoxy primer as a sealer)
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Can-Am |
Mar 5 2023, 08:56 AM
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#9
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Newbie Group: Members Posts: 35 Joined: 20-November 07 From: Scottsdale, AZ Member No.: 8,360 Region Association: None |
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worn |
Mar 5 2023, 05:14 PM
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#10
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can't remember Group: Members Posts: 3,156 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
You can use epoxy over freshly sanded and cleaned metal. You then do primer surfacer or any body filler over that then seal and paint(I use epoxy primer as a sealer) Ditto. What he said! Ditto what I have been doing for the past cars. I have had no troubles with epoxy, surfacer, paint. But wanted to know if I could do even better by etching. |
mepstein |
Mar 5 2023, 05:52 PM
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#11
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914-6 GT in waiting Group: Members Posts: 19,279 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
You can use epoxy over freshly sanded and cleaned metal. You then do primer surfacer or any body filler over that then seal and paint(I use epoxy primer as a sealer) Ditto. What he said! Ditto what I have been doing for the past cars. I have had no troubles with epoxy, surfacer, paint. But wanted to know if I could do even better by etching. People etch prime when they are are painting over previously rusted metal. It helps to chemically bond and seal up the micro pitting that you can’t get to with sanding, etc. I’ve always heard the rule of thumb is epoxy over fresh metal and etch prime over previously rusted metal. But I’m no painter so follow the tech sheets. |
Van B |
Mar 5 2023, 07:07 PM
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#12
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Senior Member Group: Members Posts: 1,590 Joined: 20-October 21 From: Maryland Member No.: 26,011 Region Association: None |
Factory did etch primer, build/filler, sealer, then paint. Anything else and your gonna regret it. Etch has phosphoric acid (self neutralizing) and also seals with the solids in the paint. Second best thing to a true galvanized body.
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