| Painting over Phosporic Acid |
| yes |
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83% |
[ 5 ] |
| no |
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16% |
[ 1 ] |
| stupidest Idea I have ever heard of |
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0% |
[ 0 ] |
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| Total Votes : 6 |
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| Author |
Message |
hpw
Samba Member
Joined: July 17, 2006
Posts: 3010
Location: memphis
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 Posted: Mon Oct 05, 2009 3:53 am Post subject: Painting over Phosporic Acid |
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I did a test area on my car to see how this would work and the paint (master
series) seemed to adhere excellent. This was on bare metal, then I applied the
phosphoric acid and allowed to dry, then a small test patch of paint. Before I go
whole hog and do the rest of my areas needing painting, can any one advise me
if this is a good idea or not?
Didn't want to introduce any water(to rinse) into this if I didn't have to.
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spook
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Joined: December 30, 2003
Posts: 2038
Location: in the shop 35750
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Bart Dunn
Samba Consiglieri
Joined: May 09, 2004
Posts: 2354
Location: Sea level (Mid Atlantic)
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| Posted: Mon Oct 05, 2009 8:06 am Post subject: |
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I think Chuck actually recommends it with Masterseries, although I could be wrong. I recall that the instructions say to wash it thoroughly before applying the paint after the phos. treatment.
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TheRustySuper
Samba Member
Joined: June 24, 2009
Posts: 2076
Location: New Albany, IN
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| Posted: Tue Oct 06, 2009 6:35 pm Post subject: |
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I've also heard this. I'm doing spots of bodywork, so my car will have tons of bare metal patches that I need to paint over. I was told to use phosphoric acid in order to help my primer adhere better, since the car sits outside and I can't have any bare metal exposed.
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Stuggi
Samba Member
Joined: October 16, 2007
Posts: 1208
Location: Jakobstad, Finland
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| Posted: Tue Oct 06, 2009 10:59 pm Post subject: |
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It's supposed to be one of the best primers available, only thing better would be acid dipped, welded, acid dipped again and then hot-galvanized as they do with new cars.
The way you're supposed to use phosphoric acid is like follows.
First strip the part with thinned out hydrochloric acid. This removes everything, even steel if left on too long (several hours/days so don't worry). Wash it down properly and allow to dry. Slight surface rust should have formed, don't do anything to this, this rust is half of the primer. Now put on the phosphoric acid, and allow it to work. It should turn all the rust black (iron phosphate if I remember correctly). This is a very thin coating, but it'll make sure it doesn't rust in a very long time as you've converted all of the rust into iron phosphate. Now wash it down again, and paint it with normal primer. Put it on thick so you don't accidentally sand through it.
If you go over to shoptalkforums.com there's an excellent tutorial on how to do this.
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