Re: Removing Undercoating
[Re: 71rm23]
#155136
11/24/08 11:22 PM
11/24/08 11:22 PM
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Joined: Mar 2004
Posts: 269 Arizona
jsully
enthusiast
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enthusiast
Joined: Mar 2004
Posts: 269
Arizona
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Quote:
It would not be my choice... I still prefer using a torch to soften undercoat .and a wide scraper to remove it...
I'm using a heat gun but a wide scraper as well. Mine seems to come off pretty easy, so far. While I'm on this subject and not to deviate from the OP but here's a question related to this:
What to put/do to the metal after removing the undercoating? I would think you need to do something soon to prevent anything happening to the metal. In my case, it could be a while to take it to a body shop(if that's the process)
I just finished scrapping the undercoating off the bottom of my 70 Challenger. A $9.99 harbor freight heat gun(s) and variety of scrapers did the job well. I finished 'cleaning' with a wire wheeled grinder and 60 grit where needed. I put SEM self etching primer to keep the metal from rusting until I can seal and paint. The undercoating was the original dealer applied stuff, what a painful 'under'taking it was.
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Re: Removing Undercoating
[Re: dusterboy15]
#155138
11/26/08 09:53 AM
11/26/08 09:53 AM
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Joined: Jan 2003
Posts: 4,323 NY NY
340duster340
master
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master
Joined: Jan 2003
Posts: 4,323
NY NY
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i had done this back on my duster last summer. not a fun job. i actually haven't worked on the car since because it really tested my convictions to complete the car as well as opened up a whole new can of worms.
after removing all the undercoat, i am now going to have to paint the whole underside of the car. while i have to do that, i decided to paint the engine bay as well since i have the car all apart, why not i figured.
i used the following methods: - torch and scraper - chemical peel (some old rust bust from the 60's) and scraper - younger brother + the above methods
i would recommend using a plastic scraper if possible, as this would eliminate any unintentional gouging of the metal. if you use a metal scraper, file down the corners first.
1966 Dart GT
...down to only 1 mopar for the first time in 15 years!
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Re: Removing Undercoating
[Re: Pntastar69]
#155140
11/26/08 04:49 PM
11/26/08 04:49 PM
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Joined: Feb 2007
Posts: 86 Switzerland
swissmopar
member
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member
Joined: Feb 2007
Posts: 86
Switzerland
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We use dry ice blasting to remove undercoating. It can be done without removing the undercarriage parts since dry ice sublimes completely. I have even removed all the paint from my 1958 Corvette without hurting the original Gel Coat layer.
Last edited by swissmopar; 11/26/08 05:11 PM.
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Re: Removing Undercoating
[Re: swissmopar]
#155142
11/26/08 04:57 PM
11/26/08 04:57 PM
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Joined: Feb 2007
Posts: 86 Switzerland
swissmopar
member
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member
Joined: Feb 2007
Posts: 86
Switzerland
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How it works: Cleaning with dry ice! This new development is quickly expanding around the world. One system uses small rice size pellets of dry ice shooting them out of a jet nozzle with compressed air. It works somewhat like sandblasting or high-pressure water or steam blasting, with superior results. The frigid temperature of the dry ice -109.3°F or -78.5°C "blasting" against the material to be removed, causes it to shrink and loose adhesion from its sub surface. Additionally when some of of dry ice penetrates through the material to be removed, it comes in contact with the underlying surface. The warmer sub surface causes the dry ice to convert back into carbon dioxide gas. The gas has 800 times greater volume and expands behind the material speeding up its removal. Paint, oil, grease, asphalt, tar, decals, soot, dirt, ink, resins, and adhesives are some of the materials removed by this procedure. Only the removed material must be disposed of, as the dry ice sublimes into the atmosphere.
Replaces Sandblasting: This method is superior to sandblasting because the dry ice is soft enough not to pit or damage the underlying surface. The dry ice sublimes quickly into the air and only the removed material must be cleaned up. Dry Ice blasting eliminates equipment damage in two ways. First, dry ice does not erode or wear away the targeted surface as traditional grit media and even wire brushes do. This means that surface integrity and critical tolerances are preserved and equipment will not have to be replaced due to surface erosion common with sand, glass beads, and other abrasive media. Second, with traditional cleaning methods, equipment is often damaged (bumped, dropped, etc.) while in transit to or from the dedicated cleaning area. Instead most equipment and machinery can be cleaned while in place.
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Re: Removing Undercoating
[Re: belv2vert66]
#155145
11/27/08 12:20 PM
11/27/08 12:20 PM
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Joined: Jan 2006
Posts: 3,535 Canuckville
68Cbarge
master
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master
Joined: Jan 2006
Posts: 3,535
Canuckville
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My car had sat from 1974 til now. I worked under my car- on axle stands- for 21 months. I used torch and scraper,wire brush on my drill to clean up,and hammer and an old beat up flat head screwdriver to chip away the brittle stuff.. I found a lot of surface rust under my undercoating so I had to remove it..I cleaned up it to bare metal,a coat of expoxy primer and then painted. Some areas were pitted already and I treated them with phosphouric acid and/or a rust convertor. Not perfect,but I know it will never see snow or salt and will last a long time.
Last edited by 68Cbarge; 11/27/08 12:29 PM.
'68 Newport Custom Barge on a Budget!! BOAB 1973 Satellite WAGON! 318- 3 on the tree!! 2008 Chrysler 300c HEMI!
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