Well once again I’m over my head! I’m building a ’48 Diamond T 404 hot rod and though my chassis/drivetrain disqualifies it from being a traditional hot rod I’m sure my paint question is something many here have dealt with. My problem is leaded seams. In an effort to get good adhesion to the lead I used self etching primer from a rattle can. I also used the same primer on all the new metal I’ve added. My concern is the lead isn’t very smooth and I want to be able to use polyester filler and high build primers over the self etch. As I understand it, polyester filler over self etching primer is a No No. What am I to use over the self etching primer? Ive read several contradicting opinions about using 2 part epoxy primer over the self etch and I’m just left more confused. To complicate what is already complicated- I have a fair amount of rust pitting on the body metal (that I have yet to treat or prime)-I’d like to use something like Eastwoods fast etch to kill it before priming but don’t know what to use considering the self etch/lead issue. Please , Some guidance would be much appreciated.
Deceide which brand and line of top coat you will be using. Then use the primers and technique the paint company says to use. Then you will have no problems. Simple.
There will be a few different methods guys will post, but I would do it this way. Sand off the etch primer and put on some good epoxy. The self etch may not have any extra adhesion to the lead, while epoxy will. Now, I use HOK primer, which is also a good hi-fill primer. I'm sure there are others. One stop shopping!
What makes self etching primer work is the thinner, it has an acid base. Dealing with the rust will probably remove the rattle can stuff you put on the lead. Deal with the rust, then do your body work on the bare metal or Epoxy primer, both the self etch and epoxy are direct to metal, use one or the other. The epoxy primer has a recoat window so if you miss it you will have to sand before painting over it. Sanding epoxy primer is like trying to sand a gummy bear so if yours is a long term project I would suggest doing the body work on bare metal and after removing the rust using the self etch primer, then a 2K primer, sand and topcoat.
I would avoid self etching primer like the plague! Had the body on my '36 sand blasted ( and yes, they did a good job - I saw it before they painted it) and they painted it with the self etching primer. Within a few months it began rusting. I had to re-blast it myself and sprayed it with epoxy primer - no rust now.
Self etch primer is porous and not water proof, it creates a chemical bond to metal and a mechanical bond to other primers and top coats. Do not wet sand it or allow moisture to contact it. it dry sands easily. Best not to allow your project to sit out side or do one panel at a time and cover it with a good two component primer. Used as directed it works well.
Yes, HOK primer over lead. It is an epoxy primer. It is a good filling primer for imperfections, and sands easily (relatively). Is also a sealing primer. Self etch's acid based reducer really doesn't have any advantage being used over lead, at all. Although there is variation in different brands, most epoxy primers are not recommended over etch. Some body fillers are not recommended being used over etch, either. It does have it's advantages, but you need to read both the tech sheets for the etch primer, and whatever you put over it.
OK, I subscribed to this thread to read about lead and primer, and between here and some local body men, I'm getting conflicting answers to my question: My problem is pertinent to the OP's so maybe I ain't hijacking the thread Son bought an OT car just about 3 years too new for the HAMB, so we won't discuss the car, just the work done on it previously, OK? Car had been "restored" about 16-18 years ago, and spent the last 14 years in a garage while the owner was incarcerated. The years it sat in the garage exposed what a "hack" the guy was who did the work for the previous owner. Bondo over rust, trim glued on with construction adhesive, etc. But my quetion concerns the original factory lead joints between top and rear quarters. The otherwise nice and shiny paint had bubbled in the exact outline of the factory lead joints. Several friends and acquantances who are somewhat involved in body and paint work say that the cause is that modern paints and primers and lead joints are incompatible and that the lead should be removed and replaced with plastic filler (bondo) before the new paint job is done. But a body and paint man whom I highly respect and have one car with his body & paint work says the cause is either wrong primer or inadequate cleaning and sanding. We have no way to contact the hack who did the job back then, and after seeing his work and what he covered up with bondo, etc., I wouldn't believe him anyway. Now I read here that the problem could be self etching primer or something similar. As I said car was first redone about 16-18 years ago. Was self etching primer available that far back? Could this or something similar be the problem? I don't want to remove that factory lead joint unless it has to be done.
Dave, self etch has been around for over 30 years, at least. I don't think that is the problem with your son's car. If the car was redone, it's most likely that the applier of the leadwork did not clean up the flux thoroughly. You have to wash it with water + baking soda, to neutralize the acid in the flux, and scrub it with some thinners afterwards to remove any other residue (including any beeswax/oil from lubing the paddle). If this is done, a lead repair is as close to permanent as you can get. If it was the original lead from the factory, I'd be more likely to think that whoever prepped the car for paint back then didn't do a good job, and perhaps there was residual rust near the edge of the lead that they didn't address.
I'm pretty sure the quarters were replaced at the time the hack job rebuild was done, so most likely the leading was done by that guy, and it may well be that his lead job wasn't cleaned properly as yall are saying. I did final body repair work at the ATL Lakewood Chev. assy plant back in '64-late '66, and they really frowned on our using lead for a repair unless absolutely necessary because of it being a dent in a spot with inaccessible backside so as to be unable to bump up and then metal finish. Their stated reason was that the factory lead joints were done using a special flux and lead powder slurry and big torches and we were using acid and an OA torch to tin and lead. Nowhere near as much heat to bring the acid out of the lead, and a different tinning agent. Some of what we did on repair was leaving acid in the lead pores that later leached out and spoiled the paint on a customer's new car My thoughts are to heat the area pretty hot with a heat gun, scrub with hot water and strong alkaline such as TSP, then scrub with clear hot water, followed by lacquer thinner and metal prep before applying epoxy primer. Your thoughts and comments appreciated.
I did lead fill at the GM assembly plant in Linden New Jersey for five years . The tinning butter and 30–70 lead is very close to what's available today . The biggest difference is the amount of heat I can use on a flat panel versus the sail panels we were filling . Our cars went right into the lead sanding booth immediately after filling. I am assuming the dip they used for the entire body must have neutralized any remaining acids. It sounds like your idea for prepping the lead is better than the self Etch primer I used. Nothing says disappointment like having to do it twice
I have had and seen to many paint jobs bubble over old lead seams for whatever reason. On my cars I use a propane torch and melt all old lead out. I have NO problem with new lead work . Bill Hines was a friend, and Marcel Delay leaded the cowl on my 36 roadster. But my cars from 32 to 58 lead was removed and mostly replaced with bondo or weld and metal finished
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