Yes, I have looked through the hundreds of old threads and can't find what I am looking for. I bumped the metal on my 59 out the best I could. Got it pretty straight. DP 90 the skin. Let it dry 24 hours. Now I am doing a small amount of mud work. Got the problem areas fixed. sanded through in a few places. My question is, how smooth do I have to sand the DP to recoat? Do you just knock the tops off or does it need to be sanded like you are sanding a final coat of clear. I am using dp 90 and K36. I'm doing one panel at a time. Another question. How long do you wait to NOT have to resand the DP. I always thought if you don't wait over 76 hours you could reshoot it. I have CRS. Thanks TP
Check the tech sheet here: https://buyat.ppg.com/refinishProdu...roductID=c98c3f28-89c5-467d-9983-e87c240f4c09 Says it may be recoated up to a week. After that, needs to be cleaned, sanded and recleaned.
392 hemi. Thanks for the link but I still could not find the answer. Am I over looking it? I'll go back and re-read. TP
I knock it down with 320 and repsray after 24 hrs. Have had great results. Spray color within 24 hours of dp 90.
When you say "Knock it down" that is my question. Does it need to be smooth or does it look like orange peel? I am at that point now.
I am using 180 and it's hard to cut. It's clogging up the paper pretty quick. Maybe thats my problem.
You can use the 180 paper just not for your final coat before paint because it's to ruff. The dp90 does clog up the paper it's def not the easiest to sand from that aspect. Make sure your keeping it wet with plenty of water that will help with the cloging to.
I have done 240 wet sand over dp and it cuts out the orange peel but then go over again with 320 for a smooth finish for the final. If you let it dry for over a month or so the dp becomes hard as a rock to wet sand.
I just knock the top off the orange peel. It is smooth enough after that to spray over. When wet sanding, I use a neutral ph detergent in my bucket and keep the paper very wet to prevent clogging. I have shot color weeks after doing this with no adhesion/printing issues.
I have to be careful here.... First off- I would consult the TECH SHEET. But it takes a pretty long time before epoxy primer is hard enough to feather out without clogging finer sandpaper. It isn't really designed to be sanded, but to be used in more of a wet-on-wet application. If it is really cured (i.e. a couple of months old in 80+ degree temperatures) I would DA it with something like 150 or 220 DA paper. But if it is still fresh enough to clog sandpaper-- as long as it has a decent etch- you should be OK on recoating. If it is till relatively soft, but outside of the 24 hour window like you say, by far the easiest way to do this is with a Scotch-Brite pad. I think that the red ones are equivalent to a 320 grit etch. Those are what I would use. They are expensive but well worth it. I would personally ALWAYS etch the epoxy with 80 grit before applying plastic filler- I don't care how much it clogs the paper. Unless you are working in a climate controlled environment- you don't know exactly how dry the epoxy is. Use an older piece of 80 you have lying around from sanding filler. This is just a personal preference for me- cause I freak out when i start block-sanding filler, and the edges don't feather out smoothly. i know that the paint reps will always recommend a solid barrier of dp40 or dp90 between the bare metal and filler- especially if you are working in a humid environment. Plastic filler gets hot as it dries and condensation can form under the filler for this reason. If you are working in humidity (Texas?), i would follow the tech sheets to the letter with regards to using plastic filler over epoxy primer within a specific drying window. Anyhow- I hope that I answered your question.
Good advice about the scotchbrite pad.....if you are going to spray k36 over it I wouldnt worry too much about the orange peel. I think the ticket here is to open it up and put a tooth in it so you get a chemical and mechanical bond between your old DP and your new coat of DP. I hope you bought your product already....PPG went up 8% in price to the distributor 11-01-08 You can always mix reducer in to use it as a sealer and it will have less orange peel and less build.
What size tip and air pressure do you use to keep the dp 90 as smooth as possible? When I shoot the dp as my final sealer seems like it should be as smooth as possible. I am by know means looking for a show car but want it nice. Thanks to everyone who has offered advice.
Also- I would personally NEVER wetsand epoxy primer when you are working with 1-2 wet coats over bare metal or plastic filler. Never. K36 will easily stick to relatively new epoxy or lightly etched (320 or finer)- there's no retrictions that require wetsanding at this point. Also, if you are primering with dp90, then doing filler work, I would follow this process: 1) recoat the ENTIRE panel with epoxy (or at least any bare metal areas) before coating w/K36 2)then spray the entire panel with k36 before you do any wetsanding. You can double coat the plastic filler areas w/K36 for material to block with, and the solid barrier of urethane primer gives you a cushion between the bare metal and the water. Yes- this all gets expensive, but you don't want rust film creeping round under your primers. Just as primers can seal moisture OUT- they can seal moisture UNDERNEATH them. Plastic filler is porous- and will draw in moisture like a sponge. that's somewhat of an exaggeration, and the modern fillers are better about this, but it is still a realistic concern. Alot of people are just using sprayable polyester for the first blocking coat over fresh bodywork. It can easily be dry-sanded so you remove the moisture component altogether, and it is THICK. It is also relatively cheap. Sprayable polyester is a little bit harder and more brittle than urethane primer (K36), so I would be more careful about adhesion issues. You will need a more aggresiive sanding scratch to allow the polyester to adhere and feather- but it is well worth it. if you folow your job all the way through, and watch your costs, you will see that polyester is a really great way cut cost and give your bodywork a helping hand. K36 is honestly more of a production primer- with alot of versatility and speed built into it. The price reflcets this. Guys at the paint counter will amost always pitch it becasue that is where the bulk of their business comes from- not restorers or hot rodders. Anyhow- sorry for the book, but deserves being mentioned.
Fridge, this is basicaly how I am doing it. I am working one panel at a time. I am also buying my product by the quart. I know it's more expensive this way but I may go a month before I get back on it. I don't want to open up the cans then it set for a monthy. Doesn't seems as expensive when a drag it out like this. Thanks TP
I haven't used the "new" DPLF primers, but when I was using Ditzler, 90 sprayed out the roughest of all the epoxy primers- no joke. Dp40 wasn't bad- but I would never use it as a sealer under basecoat or straight urethane..... but somehow dp50 grey laid down ****ery smooth, flashed off beautifully, and allowed great coverage. I'm not sure how this works, but 90 was always the peeliest and stayed gooey the longest-attracting dirt and other **** somehow. It would straight up ruin a black job. Sorry- I have no further wisdom on this, buddy. Well, I hope this help- that's all. I know what you mean about cost. Not to harp- but try a gallon of sprayable polyester sometime, it's the hook for restoration type work. I think you can still get a gallon online for like $50 (could be wrong- haven't looked in awhile)
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