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brainwash
Samba Member
Joined: June 22, 2014
Posts: 64
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 Posted: Sat Aug 22, 2015 5:07 pm Post subject: Newbie Q: How do I treat this pitting? |
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I just wire wheel brushed the rain channels and some of the top of my 78 Westy and have come across some not previously visible pitting. I guess the PO had painted over rust? What should I do here? I've wire wheeled it as much as possible not sure how to treat it.
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'78 Westfalia |
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Deutsch
Samba Member
Joined: August 07, 2003
Posts: 295
Location: E-town, KY
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| Posted: Sat Aug 22, 2015 5:25 pm Post subject: |
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If its not too deep, I'd paint the pitted metal with PPG epoxy primer. Then apply a thin coat of body filler onto the primer to fill the pits.
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The German |
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Mike Fisher
Samba Member
Joined: January 30, 2006
Posts: 17969
Location: Eugene, OR
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| Posted: Sat Aug 22, 2015 6:29 pm Post subject: |
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Treat all the bare metal with Rust-Prep or similar phosphoric acid rust killer first, before filler or spraying primer etc.
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buguy
Samba Member
Joined: November 17, 2003
Posts: 4915
Location: Port Orange, FL
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| Posted: Sat Aug 22, 2015 6:54 pm Post subject: |
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| Both answers are correct. The best way would be to get a spot blaster and really get that rust cleaned out, then epoxy primer. If you dont have access to a blaster (although if your restoring a car/bus I would get one) then some phosphoric acid before your epoxy. I know it looks like you got all the rust out with the wire wheel, but you didnt. So it needs to be treated first. |
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brainwash
Samba Member
Joined: June 22, 2014
Posts: 64
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| Posted: Sat Aug 22, 2015 8:44 pm Post subject: |
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I've got some rust bullet metal blast with phosphoric acid in it. Was told that 4:1 water:vinegar solution would work but plunked down the $20 (pound foolish?).
Will be needing a blaster of some kind soon, but not planning to shoot my whole bus. Wanting to remove as much rust as I casn for now and save up for a professional paint job some day.
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modok
Samba Member
Joined: October 30, 2009
Posts: 26776
Location: Colorado Springs
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| Posted: Sun Aug 23, 2015 11:30 am Post subject: |
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That is more than clean enough to apply paint. Just paint it!
You'd have to be seven feet tall to see the pitting......so why fix it? |
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Mike Fisher
Samba Member
Joined: January 30, 2006
Posts: 17969
Location: Eugene, OR
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| Posted: Sun Aug 23, 2015 12:54 pm Post subject: |
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Don't spend $5000-10,000 on a professional paint job. Paint it yourself for $1000 and you will be able to spot repair/paint it when it gets dinged up. 
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69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
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'68 Karmann Ghia sold
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buguy
Samba Member
Joined: November 17, 2003
Posts: 4915
Location: Port Orange, FL
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| Posted: Sun Aug 23, 2015 2:33 pm Post subject: |
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| modok wrote: |
That is more than clean enough to apply paint. Just paint it!
You'd have to be seven feet tall to see the pitting......so why fix it? |
Now punch yourself in the nuts for saying that! |
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brainwash
Samba Member
Joined: June 22, 2014
Posts: 64
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| Posted: Sun Aug 23, 2015 3:16 pm Post subject: |
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| Mike Fisher wrote: |
| Don't spend $5000-10,000 on a professional paint job. Paint it yourself for $1000 and you will be able to spot repair/paint it when it gets dinged up. |
I'm liking the sound of that much better!
I'm new to the body/painting world, but willing to learn! As long as the cash outlay for equipment capital doesn't hit the thousands. And since I've got the roof off and am painting the top and rain channels, may as well remove everything else as well.
In that case, should I just gut it and have it blasted professionally?
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Sun Aug 23, 2015 7:28 pm Post subject: |
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| brainwash wrote: |
I've got some rust bullet metal blast with phosphoric acid in it. Was told that 4:1 water:vinegar solution would work but plunked down the $20 (pound foolish?).
Will be needing a blaster of some kind soon, but not planning to shoot my whole bus. Wanting to remove as much rust as I casn for now and save up for a professional paint job some day. |
Uh....no.  .....water and vinegar will do nothing. It may remove a little rust.....but will NOT produce iron phosphate conversion....which is what phosphoric acid does.
Its nit just the use of a generic acid....jts a specific acid.
Also....for pitting clean it first with small amounts of hydrochloric/muriatic acid. It will dissolve every spec of rust down to bare metal even in the smallest pits.
Rinse it with a small amount of baking soda and water. ...then rinse again with clean water. Lit it sit for a day or two and create a fine layer of surface rust. Then hit it with phosphoric acid to convert that fine layer of rust to iron phosphat.....which is ideal primer.
Phosphoric acid is useless in bare metal. It must have rust to convert.....or it does nothing. The issue is that it, cannot convert what it cannot soak into. It will not, convert rust deeper than .002-.003" thick. So if you first dissolve thick rust then let it flash rust and then treat with phosphoric acid....you know its converted all the way through. Ray |
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brainwash
Samba Member
Joined: June 22, 2014
Posts: 64
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| Posted: Sun Aug 23, 2015 8:19 pm Post subject: |
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| raygreenwood wrote: |
Uh....no. .....water and vinegar will do nothing. It may remove a little rust.....but will NOT produce iron phosphate conversion....which is what phosphoric acid does.
Its nit just the use of a generic acid....jts a specific acid.
Also....for pitting clean it first with small amounts of hydrochloric/muriatic acid. It will dissolve every spec of rust down to bare metal even in the smallest pits.
Rinse it with a small amount of baking soda and water. ...then rinse again with clean water. Lit it sit for a day or two and create a fine layer of surface rust. Then hit it with phosphoric acid to convert that fine layer of rust to iron phosphat.....which is ideal primer.
Phosphoric acid is useless in bare metal. It must have rust to convert.....or it does nothing. The issue is that it, cannot convert what it cannot soak into. It will not, convert rust deeper than .002-.003" thick. So if you first dissolve thick rust then let it flash rust and then treat with phosphoric acid....you know its converted all the way through. Ray |
Thanks for the great advice, Ray! 
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benchracer1
Samba Member
Joined: September 24, 2006
Posts: 583
Location: ramona
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| Posted: Tue Sep 29, 2015 5:29 am Post subject: |
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| I've heard that muriatic acid can actually change the properties of the metal and make it brittle. Are you talking about very small amounts? ....Steve |
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Air-Cooled Head
Samba Member
Joined: October 15, 2002
Posts: 4070
Location: Chicago Suburbs
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| Posted: Tue Sep 29, 2015 10:19 am Post subject: |
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| benchracer1 wrote: |
| I've heard that muriatic acid can actually change the properties of the metal and make it brittle. Are you talking about very small amounts? ....Steve |
This is true, but it takes quite a bit of time.
Small amounts. Short exposure.
For small areas, a teaspoon of acid, a few minutes at most. Rinse time.
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benchracer1
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Joined: September 24, 2006
Posts: 583
Location: ramona
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| Posted: Tue Sep 29, 2015 10:54 pm Post subject: |
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| What is considered short exposure |
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benchracer1
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Joined: September 24, 2006
Posts: 583
Location: ramona
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| Posted: Wed Sep 30, 2015 4:03 am Post subject: |
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| Oops, I see where you said a few minutes at most. |
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Volks Wagen
Samba Member
Joined: February 13, 2013
Posts: 2926
Location: Germany
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| Posted: Sat Oct 03, 2015 2:03 pm Post subject: |
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| brainwash wrote: |
| Mike Fisher wrote: |
| Don't spend $5000-10,000 on a professional paint job. Paint it yourself for $1000 and you will be able to spot repair/paint it when it gets dinged up. |
I'm liking the sound of that much better!
I'm new to the body/painting world, but willing to learn! As long as the cash outlay for equipment capital doesn't hit the thousands. And since I've got the roof off and am painting the top and rain channels, may as well remove everything else as well.
In that case, should I just gut it and have it blasted professionally? |
How'd it go so fast from treating a few unnoticed/unexpected pitted spots to completely gutting the bus? Maybe I'm just getting old or something.
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buguy
Samba Member
Joined: November 17, 2003
Posts: 4915
Location: Port Orange, FL
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| Posted: Sun Oct 04, 2015 5:31 pm Post subject: |
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| If you are restoring the whole thing. Then, yes. Gut it and have it blasted. Its really the only good way to be sure all the rust is gone. |
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Jon's62
Samba Member
Joined: June 16, 2015
Posts: 55
Location: Ontario
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| Posted: Thu Oct 08, 2015 7:50 am Post subject: |
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| Once the rust was gone, I would spray with high build primer then apply filler (from a pro paint shop supplier, not the cheap stuff). |
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jpjohns
Samba Member
Joined: May 03, 2014
Posts: 882
Location: Harrisonburg, VA
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| Posted: Thu Oct 08, 2015 9:52 am Post subject: |
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| buguy wrote: |
| modok wrote: |
That is more than clean enough to apply paint. Just paint it!
You'd have to be seven feet tall to see the pitting......so why fix it? |
Now punch yourself in the nuts for saying that! |
haha, I was thinking that. If I was 7 feet tall, wouldn't I be farther away from the pitting?
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"Scrapyards are for quitters" - Beetlenut (a Samba member) |
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