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Joined: Feb 2003
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I have a 66 Chevy fleetside truck and am doing some body work on it right now. I had the bed sandblasted and then cleaned and primered it with a primer for bare metal. I had to leave the bed out for one day and while there was no rain, a heavy dew fell. Obviously, I didn't have enough primer on, or wrong primer. I now have several surface rust areas showing up. The truck will only be a daily driver. Would it be most logical to sand these areas, and reprimer, or could a good rubbing with some naval jelly or some other rust converter be practical?
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Joined: Dec 2000
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No; Sand them back in the rust area only. Then obtain some 'eopxy primer' from an Automotive Paint Store. Put on plenty, expecially on the horizontal surfaces. This will "hold things" till you can paint it. Kragen sells a 'bed spray' that works good too. It's really tough to get off, if you want to later. Good luck. 
John M., I.I. #3370
"There are no shortcuts to any place worth going". -Anon
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Joined: Feb 2003
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Thanks guys. I hate to take a step backwards, but I REALLY don't want the rust to come back thru! I guess I need to sand to bare metal in those areas?
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Yes; Just those places. Then use the epoxy AND the respirator with head gear & long sleve shirt('coveralls'better) if in a booth. It's the 'hardner' that is toxic. Spiling it on your hands can be harmful too. The same applies to painting and clear coat (second stage). Later It's just light sanding before painting. Good luck. 
John M., I.I. #3370
"There are no shortcuts to any place worth going". -Anon
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Sanding is good if you can get to all of the rust. But if you have areas where its tougher to get to or short on time you can also apply "one step" by MAR-HYDE. This stuff is great it causes a chemical reaction with the rust and when dry (black) creates its own primer ready to paint.
Hope this helps
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Sorry to be commenting late, but I just read the thread. Sandblasting produces a surface texture (duh) that promotes mechanical adhesion, but the peaks have to be covered to resist corrosion. A thin coating of a primer hasn't got much chance of providing this protection since like most liquids, it pulls away from the peaks and flows to the valleys of the sandblast texture. The primer should be applied thin since it's only purpose is to promotes adhesion and provides the best characteristics of a bonding agent between the metal and the topcoat. The topcoat will have different characteristics since it's purpose is to prevent moisture permeation to the metal surface and retain it's looks. Typically, the primer should be left on only long enough to apply the topcoat. It wasn't designed as an effective topcoat. Applying primer thick enough to provide long term corrosion protection over a sandblasted surface means using it incorrectly. That is the job of the topcoat.
John M. Schluter
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I really have to disagree with the above although it is in part correct. First of all on a sandblasted surface there is no problem or should there be laying your epoxy down. Two wet coats with proper flash times inbetween coats. The epoxy is the best for adhesion and for sealing the metal to protect it from moisture. It can sit on there for years and will not have an issue with rust. When you are ready to start puting on your filler and you have gone past the recoat window which in a lot of cases is 7 days you just scuff and reshoot one wet coat of epoxy and you are good to go.Now you can put your filler on,2K urethane primer or polyester primer on for blocking and filling. I use the epoxy with about an ounce per quart for a sealer. Epoxy is more chip resistant and your gloss retension is by far greater.I will also add that some of the most expensive cars out there are being done with epoxy only. Using a high end epoxy all the way thru and leaving enough cure time ensures that you will have no shrinkage issues and you are not putting on 3 or 4 diff products before the base and clear. Tech manuals guys read the tech manuals. Here's a good rule of thumb if you get a project and it just has primer on it and you don't know what it is. After the primer is cured take a cloth and put some laquer thinners on it and wipe a spot. If it comes off then whats ever on it should come off and reshoot.
1946 Chev Aerosedan Most southernest inliner in Canada
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Your correct (Mr. Morgan) about the primer etc. The situation is that; most don't know how to sandblast the older vehicles and can cause more harm than good. Unless done by a professional, sandblasting isn't the "best way" any more. Happy trails. 
John M., I.I. #3370
"There are no shortcuts to any place worth going". -Anon
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Glass media is the best for stripping paint,rust,body filler.
MBHD
12 port SDS EFI
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