Hi: First time at this and I'm kinda winging it as I go here (with help of all I can read and the tech sheets). Anyway, I have a door to paint that is not on my truck ('90 Bronco II). The door was taken to bare metal and a major dent removed and bondo work done to make the repair. The paint shop recommended two part expoy primer so I got what I needed. The first attempt went halg good half bad. The inside of the door and around the edges went well. The outside looked good when sprayed but very rough after dry and I found that after 7 hours under the surface the primer was still gummy (I tried sanding to smooth a little and a good sized chunk pulled away from some bondo). I figure I got it too thick because I know the mix was to the specs for the product. Outside went back down to metal. Now going to touch up the bondo to get the contours back to where they need to be. Then want to prime with epoxy primer and follow with a Dupont 2K Primer-Filler to alllow for sanding to what I want for a smooth finish for the color basecoat. From what I've been reading this primer-filler is what I should be doing over the epoxy primer. Am I correct with this? Asking because I sick of sanding this door and don't need to waste any more money on paint that is too exspensive to start with. Thanks for any help you can give.

 

You went all down to metal again? That may be good being that you won't have to deal with painting over somewhat fresh material and you had stuff peeling leaving chunks. What I would do if you stripped it all back down to baremetal is sand the baremetal with around 80-180 or if you already sanded, go over with a red scotchbrite pad to take care of any flash rust that has accumalated on the surface, wipe it down with some wax and grease remover, and get a coat or two of epoxy primer on it right away to protect the metal. You can then procede and do your filler work over the epoxy. I would let the epoxy primer set overnight. The next day do your filler work and when done shoot more epoxy over the filler and baremetal, may just be as easy to re epoxy the whole door. After letting the epoxy flash off for maybe an hour or so, then apply your urethane primer over the epoxy. You can lightly scuff the epoxy with 180 where you will be applying your filler, but after overnight you should be well within the window to apply your filler over it without sanding. The urethane 2k will have more fill and easier to sand without gumming up the paper. After the urethane primer has set the amount of time stated in the tech sheets, You can then procede to sand the urethane primer with final grit for paint or block sand it and apply more coats of urethane primer. That epoxy primer may just have been still been gummy after 7 hrs. Many take up to a week or so to fully cure. If you piled on coats without allowing enough flash time, this could be the cause of your adhesion problems. You don't find much better sealing and adhesion to bare metal then epoxy, but the cure time is slow and it will stay gummy and clog sandpaper for awhile. It will wetsand better then doing it dry. Take your time and allow plenty of flash time. And if the weather is humid at all that will also slow down drying of material. Being you are not doing this in a production shop, you have the luxury of not rushing things and taking you time allowing extended flash time between coats of material.

 

This may not be for you - I use 500 wet for the 1st coat of primer - and 1000 wet for coats after that. It takes a bit longer but you can get a glass-smooth finish. Some shops use 1500 or 2000 wet to buff out laquer paint, using LOTS of water.

 

Went and bought some Dupont Ultra Primer today. Got home and finished the bondo work to get the contours back where the door was originally dented up bad. I'm no pro and am not even looking for a "like new" result but rather an acceptable result considering the whole truck needs new paint. At any rate, I shot two coats of the epoxy primer over the bare metal and bondo, then followed that with three coats of the Ultra primer. The finish looks much better now. If I had been able to I would have top coated today also. The Dupont sheet says that after two hours the primer must be sanded and recommends using a 400 grit. I still have two base coat colors and the clear to do. That will probably need to wait until next weekend. There is nothing stated as to how long is a max before it must be top coated so I assume it doesn't matter except I'll wait to sand until I can do the rest of the painting right away. I'm much more satisfied with the finish now than I was with just the epoxy primer. Hopefully the color and clear will go without glitches and I can get this monkey off my back! I hate body work! Tear things apart and get all hogged up with grease but body work sucks.

 

Your primer can sit as long as you would like. As long as its not being driven long exposed to the elements. In fact leaving it sit may be better. Urethane primer does not shrink to the extent of a lacquer primer but it does shrink some. Leaving it sit will allow it to shrink before you do your sanding. I believe the 2 hours they were talking about is the minimum amount of time to sand or the time you can paint over it if reducing and using as a sealer.

 

Thanks for the help. Priming is finished except for sanding. I had to resand the the fisrts attempt off. Second try went better and I applied three coats of Dupont ULtaProductive white primer over the expoy primer. This is much more sandable and gave me a much better surface to stat with. Next are the Bc and CC. I started a new thread with some painting questions for a two tone if you can help with that please read and reply.Thanks again.