Using DP90 for final finish

W

wrndln

Well-known member
I have primed some of my fender support brackets and other brackets with PPG DP90 epoxy primer and the finish looks really nice. It has a nice semi-gloss sheen to it. I am wondering if I could just leave the brackets with the DP90 as the final finish. I have heard that this epoxy primer does not have a good UV characteristics, but the brackets I am referring to would not see the direct sun, at least not long like the outside of the car would. Has anyone done this before? I would rather not use a high gloss finish like PPG Concept and I have had mixed results using DX685 flattener to dull the Concept to a semi-gloss.
 
I have heard of a lot of guys using it under the hood of cars for fire walls and fenders wells etc. I have used it on Model A Floor boards and body wood with great results.
Ken
 
I don't know that it matters, but the fender brackets were originally dipped like the fenders albeit only one coat. With that said, DP is a little flatter that semi-gloss. It holds up quite well but in reality it's actually a "dark gray". If you don't mind it not really being black then go for it. It will survive just fine.
 
PPG recommended the original DP90 for use on chassis components without a top coat for the first few years, then later recommended top coating it. It seems to me that a couple coats of DP90 that will not see sunlight or extreme exposure to salt and/or water would hold up very well. 'Problem is, the original DP was replaced some years ago with DPLF (90 is black, 40 is gray, 74 is red oxide and 48 is white). If the satin finish with minimal work is the result you're after, the DPLF's would probably work in minimal exposure situations, as they make an excellent sealer. However, don't take my word as a factory recommendation. Google or call PPG paint tech. By the way there is a recommended corrosion fighting pre-primer for the bare metal under the DP, its PPG 1791/1792. It's inexpensive and makes for incredible adshesion, if your metal is properly cleaned and prepped first. The 1791/1792 alone will hold bare metal parts from rusting in dry storage for years. It is semi-transparent gold/brown.
 
I use the DP 90 as a base coat and then use K36 or Ever coat euro Fill over that.
I have not had any problems with that combination. Is there any down side to 1791/1792??
Thanks,
Ken
 
No down side to 1791/1792 that I know of other than it does not adhere well to shiney new, unsanded steel. If the 'blasted or sanded steel is chemically cleaned and acid etched (I go for overkill or fail-safe), all the better. I can't scrape it off with my pocket knife, that's my adhesion test. I believe it greatly improves the adhesion and corrosion resistence of the DP and always use it. It is recommended to spray on only one thin coat. The solvents in the DP will soften the cured 1791/ 1792 enough to physically bond with with it, if it has dried more than a couple hours. Again, consult the manufacturer's recommendations. But, I have sprayed over it a month later and had excellent adhesion, because the DP solvents will still "re-activate" the surface. I have parts that I sprayed with it 8 years ago, in dry storage, that are showing no dark splotches or other indications of rust. By itself, it will not tolerate rain or water, though, as it it has no sealing properties. Lacquer thinner will soften it, which has proven to be an advantage rather than a weakness, since I will sometimes spray a long-storage part with lacquer thinner before overcoating it with DP. I have tested the adhesion of this process or I would not mention it. Another advantage is that it can be sprayed over (no interim DP, primer or sealer) with urethane single stage where surface texture quality is not important. I am not a PPG dealer or promoter, but I have a lot of cars out there with no pre-mature deterioration or failure in decades and think choice of products has something to do with it. Probably most manufacturers have products that will produce impressive results, if recommended procedure is followed. And that is a pretty sure way to never have to worry about how many years later you'll be doing your paint job over. www.olympic-speedsters.com
 
DPX170 or 1791 is not intended to be left uncovered and it is not intended to be topcoated with DP. It also cannot be directly topcoated with color, basecoat or single stage.
I am a firm believer in etch and wash primers when used properly, I am not cutting on these primers, they are excellant for what they are intended for.
From memory, I believe the tech sheet says NOT to acid etch before these primers. I have not used acid on steel for years. Even after 25+ years I still check the tech sheets daily.
They are 1K products so they need to be topcoated with surfacer or sealer.

You will NEVER find a recommendation to spray lacquer thinner over anything to soften it for topcoating! We'll get a good laugh out of that one at work tomorrow.
Do it right the first time, the methods on the tech sheets are proven to work. Varying from the recommendations are a gamble you are welcome to take, just understand your likelyhood of failure is much higher than it is when following the tech sheets.


DPLF is a much better product with 401 hardener (watch for induction period) than it is with 402 hardener.
Use the 401 with DP90LF and it will work great if not exposed to UV.
685 flattener works great in Concept or PPG CPC AUE-100. You need to have sufficient film build to get it to flatten properly. Two good coats minimum, maybe three if you are little shy. Let it dry thoroughly before evaluatin the sheen.
 
Try my tests. I would not post anything that was not proven by severe testing and decades of service. Checking tech sheets daily is a practice I believe in also. You could scrape test any of my 10 and 20-year-old and older paint jobs before you laugh without knowledge. Read my posts again and you will see that I said to consult PPG tech. Yes, any procedure that varies from the manufacturer's recommendation voids any manufacturer's warranty and puts all risk and responsibility on the painter. Again, I posted a procedure that works unquestionably well, recognizing that those corresponding on that subject on the barn have the professional maturity to understand and experiment with my deviations.
 
Jim Huseby said:
Try my tests. I would not post anything that was not proven by severe testing and decades of service. Checking tech sheets daily is a practice I believe in also. You could scrape test any of my 10 and 20-year-old and older paint jobs before you laugh without knowledge. Read my posts again and you will see that I said to consult PPG tech. Yes, any procedure that varies from the manufacturer's recommendation voids any manufacturer's warranty and puts all risk and responsibility on the painter. Again, I posted a procedure that works unquestionably well, recognizing that those corresponding on that subject on the barn have the professional maturity to understand and experiment with my deviations.
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On the contrary, many readers or posters are DIY newbies to the painting field. They can be easily mislead.
Not putting any newbies down, I have plenty of areas where I am am inexperienced.
 
DP90 will not hold up over time and will gray out and look poor. If you have a Tractor Supply nearby they have a great chasis/tractor black and it's pretty close to an original finish in color and sheen. It's cheap too.


Tim
 
I must admit, my experience was with the old DP90 and the DPLF. I can't say how well the DPLF will hold up. Back when I was restoring the Roadster I borrowed an old grinder stand from a buddy to mount a Baldor buffer motor on to do my stainless and plating prep. I had to store the stand outside for a short time and it rusted in places. Shortly after completing my "project" I blasted his grinder stand and sprayed it with DP90 and returned it to him. He has left it outside for almost 15 years now and still says it looks like it did when I returned it to him.
 
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