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The procedure I keep hearing when restoring a car is to take the car down to bear metal, and then use Epoxy primer for a base on the bare metal, and then put the urethane high build primmer over that. What happens is I end up sanding so much of the epoxy primmer off leveling the surface that I feel I should skip the epoxy part and only use urethane primmer. What do other think?
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TR2/3/3A Epoxy primer
- Thread starter sp53
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Epoxy has very strong adhesion to all kinds of surfaces, so it's great to use over bare metal and inaccessible places where you just couldn't get all the old paint off. You should scuff sand it for better adhesion of the subsequent paint, but (as you discovered) it's easy to sand through it if you do more than that. The polyurethane primer can be built up in layers and sanded to get it smooth as a baby's butt; if you sand through it, you still can spray more polyurethane, or, if it's only a couple small areas that don't go through the epoxy, just leave it alone. Together they make a nice combination.
You can use only the polyurethane, but you lose the adhesion advantage of the epoxy, and if you sand through it, you MUST respray it. Also, check the data sheet for the polyurethane primer; sometimes the manufacturer recommends specific prep for a bare-metal surface.
On my TR, I used this two-primer system. I used both primers on outer surfaces, but only the epoxy on places like wheel wells, the trunk, and the engine compartment, where appearance just didn't matter so much.
You can use only the polyurethane, but you lose the adhesion advantage of the epoxy, and if you sand through it, you MUST respray it. Also, check the data sheet for the polyurethane primer; sometimes the manufacturer recommends specific prep for a bare-metal surface.
On my TR, I used this two-primer system. I used both primers on outer surfaces, but only the epoxy on places like wheel wells, the trunk, and the engine compartment, where appearance just didn't matter so much.
CJD
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The goal is to use the epoxy primer in one color, say light grey. Do not sand that primer coat before spraying your high fill primer in a second color...say, black if you are planning a BRG or black top color. Then, you sand the top primer until you see the grey just starts to show through. Stop sanding and apply as many re-sprays of the black primer until it sands smooth without cutting into the base primer. This system prevents you from sanding through to bare metal and having to re-spray the epoxy coat.
So the epoxy is the protectant for the base metal. The top primer is the to fair the body for the top color.
So the epoxy is the protectant for the base metal. The top primer is the to fair the body for the top color.
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Before I started painting my TR, I visited a number of auto-paint forums and just hung out trying to absorb some of their wisdom. It seems that there was some degree of controversy over using body filler before or after epoxy priming. Putting it over the epoxy was a minority opinion, but still many knowledgeable people favored that. However, most apply the filler to the metal, then prime.
I put the filler directly on the metal. However, there was one place where I found a problem after epoxy priming, and I used a little filler on top of lightly sanded epoxy with no apologies, then used the polyurethane primer. It didn't cause any problems. These modern paints and fillers are amazing products, and I think they are more robust than many people admit.
I put the filler directly on the metal. However, there was one place where I found a problem after epoxy priming, and I used a little filler on top of lightly sanded epoxy with no apologies, then used the polyurethane primer. It didn't cause any problems. These modern paints and fillers are amazing products, and I think they are more robust than many people admit.
CJD
Yoda
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My paint guy says to prime first, then glaze. I still have not brought myself to do that yet. His logic is that the putty and/or glaze is porous, so it will allow moisture through to the metal. A layer of primer prevents rusting under the glaze. I rationalize that if the top coat is good, then there will be no moisture to absorb into the filler.
In the end...either way works...
In the end...either way works...