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  #31 (permalink)  
Old 09-19-2007, 12:04 PM
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BondoKing-

Thanks for all the great info (and the links- I guess this is a subject that gets beat to death!). This is making a lot more sense to me now.

If I am correct, it sounds like I can safely do this:

1. Sand blast the entire car
2. Immediately acid wash each part after blasting
3. Clean with Prep Solvent
4. Apply Epoxy Primer
5. Scuff areas for filler
6. Body filler & sand
7. Urethane build primer & sand
8. base coats (with or without sanding)
9. clear coats (with or without sanding)

One BIG question about dealing with a sand-blasted car:

After blasting I will have a lot of blast media residue to deal with. Since the metal will begin rusting right away, I probably don't want to rinse/clean the body with water. Obviously, compressed air won't blow all the residue away. If I just spray the acid wash right onto the bare metal that has blasting residue on it, when I go to clean with prep solvent (much later, but just before applying the epoxy), will the prep-solvent and wiping take care of all the blast residue?

I just don't want to paint over blast residue, and I don't want to rinse the car with water...how is this generally handled? Or am I worrying too much (impossible, right?)?

And thanks for everything.

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  #32 (permalink)  
Old 09-19-2007, 07:05 PM
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Sandblast your jambs, floor, engine compartment, window openings, but don't sandblast the exterior surfaces unless you have experience and can control the blaster for no metal warpage. A 67 Triumph is a tiny car and it wouldn't take very long to strip the exterior with chemical stripper, a razor blade scraper, sanding or a combination of all. Your metal should have a blasted texture or be sanded with 80 grit prior to applying any epoxy. Clean it well with wax and grease remover. Once the parts are in epoxy you can work any damaged areas at your own pace. Fillers can be applied to epoxy primer without the need for sanding if done within the epoxy's recoat window-but after the recoat window is up and the epoxy reaches full cure you'll need to scuff it with 180 grit for texture before any fillers are applied. Read the tech sheets on the primer you are using and if there's any question contact the manufacturer. Starting with a quality epoxy over clean and textured bare metal is the foundation for a job that will outlast you and I.

You've got a few choices on primer surfacers, polyester for heavy fill work, urethane, and epoxy hybrid types. Stay away from lacquer 1K surfacers. Also stay away from the acid wash products-they are not needed when using quality epoxy and can make for some mysterious problems down the road if not used correctly. Most acid etch primers should not be applied over sandblasted metal.
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Old 09-19-2007, 08:00 PM
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Thanks for the input.

Yeah- the more I read, the more I am shying away from sandblasting any flat panels.

If I go with chemical stripping & sanding, then go straight to epoxy, should I be concerned about the seams in the body? As you probably know, British cars are notorious for having a lot of seams where certain permanent body panels meet (front valance, rear valence, turtle deck, etc...). This is why I was leaning towards an acid wash- so that I would get some protection down in the nooks and crannies (and there are a lot of them!) in this old car.

My biggest concern is getting some protection in those areas that I will not be able to reach with sanding- I am expecting that there will be a small amount of surface rust in those seams that I simply will not be able to reach.

What do you think- should I just flood those small seams with a zinc chromate primer before applying epoxy???
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Old 09-20-2007, 05:12 AM
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Sometimes I spread the seams open between the spotwelds and use a spot blaster to get as much corrosion out as possible, then epoxy prime, apply a urethane seam sealer and close them back up with hammer and dolly. This works well on accessable areas. It's also very important to treat these seams from the backside with cavity wax if possible. Bottom line is, trapped acid in these seams is worse than leaving some light corrosion and sealing it off from both sides. Cut the oxygen supply off and the oxidation will stop. In cases where the rust is severe within the seams you should section that area out, remove the corrosion and weld it back together or make a replacement piece.
A quality epoxy will have a good amount of Zinc Phosphate in it for corrosion resistance.
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Old 09-20-2007, 07:18 AM
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Thanks, man- that was just what I needed.
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  #36 (permalink)  
Old 09-20-2007, 08:17 AM
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If I can add something, forgive me if it has been mentioned I only skimmed the thread. Do not strip this car completely at one time. Strip a panel or two MAX then prep and get them in primer before moving on to another panel. Stripping a complete car is a HUGE undertaking and unless you have a lot of time, room and experiance a guy is usually pretty overwhelmed by the job.

Brian
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Old 09-20-2007, 05:52 PM
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Good advice.

Since I'm used to only painting frames and motorcycle gas tanks (read: easy), what do you guys do to strip and prime the inside of doors? Do you slosh epoxy in there, or what? It just seems like those kind of spaces are going to be impossible to clean 100% and prime 100%.

If I am going to go through all this headache, I just want to make sure that this poor little car doesn't have to go through this again for at least another 50 years!

I just want to get every last bit of corrosion out for good...?
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Old 09-21-2007, 05:24 AM
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For the interior of the doors clean them as best you can, apply epoxy primer to any areas that can be cleaned well, treat any areas that can't be cleaned well with a cavity wax like 3M Rustfighter. I usually tape the drain holes shut wo the coating doesn't run out and let the seams soak and fill with the waxy coating then pull the tape a few days later and open up the drains. The cavity wax should be applied after your paint work is done to avoid paint contamination.
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  #39 (permalink)  
Old 09-21-2007, 06:38 AM
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I had no idea that you could flow cavity wax. It makes sense to apply it after the paint is done.

I'll let you guys know how it goes after I start stripping the individual panels with aircraft stripper & prep then epoxy prime.

Thanks for the info.
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  #40 (permalink)  
Old 09-21-2007, 06:58 AM
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My two cents, after 40 years of restoration work.
Sand blast, plastic blast or sand with 80 or rougher.
I do not use an acid wash next. The phosphate coating is great if your are doing metal work for extended time open time, then sand it all off. The best surface for epoxy is bare metal.
Next a good epoxy. This coating is only to protect the metal. Not for any kind of build up.
Next any kind of bondo work that you will do.
Then comes the urethane building surfacer or (spray poly)
Spray poly is not a primer surfacer. It is a spray-able body filler, the will be covered over later with primer surfacer.
I tried to make this as short and sweet as possible.
Dave Tallant Hot Rod Shop KC Mo
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  #41 (permalink)  
Old 09-22-2007, 05:10 AM
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Thanks. The prices I've been quoted for plastic blast media are insane - but it appears to be the best blast media choice for an old car.

Also- I am completely sold on laying down epoxy without an acid wash, then doing the bodywork over that. In the past, I have carved filler out of bare metal many times only to find rust under the bondo. It's amazing that people didn't think of bondo over epoxy back then...
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Old 11-23-2008, 05:50 PM
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What do you use during metal work?

I used a DTM Epoxy primer on my truck after complete sand blast. It worked very well. Question is, what do I spray on areas where I am now cutting and patching rust spots? This is pure metal work right now, no filler. Cut rust out and weld patch panels/pieces back. I need something that is easy ie. rattle can, while working on metal bc I can not be moving back and forth to the spray booth and spraying two part primers.
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