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Thread: Using epoxy without topcoat?

  1. #1
    Registered Member chevynut's Avatar
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    Using epoxy without topcoat?

    I was taking my Nomad apart today for blocking and was thinking that I might need to coat things like my headlight buckets, bumper braces, and a few other miscellaneous parts with something. I don't really want to mess with powder coating.

    I was thinking about using some black DPLF or SPI epoxy for some of this. I noticed this on SPI's website:

    "You do not need to top coat our epoxy on frames, wheel wells, firewalls or suspension components."

    So it seems like their epoxy might be good for this purpose. Would DPLF also work? I have some black DP90LF that I could use if it can withstand the elements without topcoating.

    Also, what would you guys recommend for coating under the tailpan area and everything behind the wheelhouses under the car? I can't really see using BC/CC under there, but maybe I should.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
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    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  2. #2
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    I would be a little concerned about using DPLF for that because of its chemical resistance----lacquer thinner will remove it even after full cure. They do have another one that I know nothing about, its DPLV. SPI epoxy is totally chemical resistant.

  3. #3
    Registered Member chevynut's Avatar
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    Thanks Lee, but I don't think I'm going to be driving through any lacquer thinner puddles.

    I guess I need to take a look at PPG's P-sheet to see if it can be used without topcoat. I don't know what to do with the underside of the body up in the quarter panels. I probably should have used DP90LF there instead of DP50LF. Maybe I'll just have my painter go ahead with BC/CC as far as he can reach up there.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

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    The only problem with using DP as a topcoat is that it has no UV resistance, but that shouldn't matter for the places you have in mind.

    I think SPI does have some UV resistance.

  5. #5
    Registered Member chevynut's Avatar
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    I'm getting to the point that I hate PPG DPLF and probably won't use it on future projects. I sprayed some parts with it and after a full day it's still soft. It has almost ZERO chemical resistance and is affected by acetone, lacquer thinner, and most other solvents...it's supposed to be catalyzed EPOXY! I sprayed my harmonic damper with it and put some rattle can white paint over the timing mark/numbers to make them more visible, and it dissolved the DPLF. You can't even sand it or wipe it down with anything without damaging it. The crap sucks and it's some of the most expensive primer on the market so you'd think it would be top notch.

    Going to order some SPI epoxy.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

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    You asked for information on it a year and half ago, I told you about its chemical resistance then, and now you are complaining about its chemical resistance????

  7. #7
    Registered Member chevynut's Avatar
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    I don't know what chemical resistance has to do with my original question of using it under my quarters and on some other parts. Lacquers were used for decades and lacquer thinner dissolves them too. Where would the thinner come from while driving?

    I knew about the lack of chemical resistance LONG AGO. I knew it could be removed with lacquer thinner but thought there was some type of solvent that it would hold up to. There's not much it resists, which makes it junk imo. It may be a good metal sealer, but with it's non-sandable properties and the requirement to use primer-surfacers over it, it's too much hassle to use anymore. I found that out on my frame when I had to do some work on it after primer. One would think a true epoxy would be more chemical resistant and tougher.

    Just ordered a gallon of SPI epoxy today. Hope it works better, and it's a fraction of the cost.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  8. #8
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    Sorry, I have to ask, how long till it sees UV light? I have used PPG's DTM ALK-200 black paint, which is easy, cheap, and seems to work great. Just pour it in the gun, and shoot it. SPI sounds like the way to go otherwise.
    For small parts I love SEM e-coat DTM trim paint, even at $16 for a rattle can.
    Last edited by 55 Rescue Dog; 09-13-2016 at 03:41 PM.

  9. #9
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    Have they changed DPLF? I've never had any problem with it.

    I think part of your problem is that full cure takes a while.

    I did notice that they have DPLV now (low volatility). I've never used that, and no idea how it compares.
    Last edited by Rick_L; 09-13-2016 at 05:06 PM.

  10. #10
    Registered Member chevynut's Avatar
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    Several people have reported in the past that their DPLF comes off with lacquer thinner, even after months of curing. I don't use lacquer thinner for anything but cleaning my gun out, but for some reason I once wiped an area of my car with it and the DPLF was attacked. The problem with lacquer thinner, according to a PhD chemist friend where I worked, is that it contains lots of different solvents. So it attacks lots of other materials, including epoxies. I discussed the fact that DPLF epoxy was attacked by lacquer thinner with him and he said it wasn't a surprise.

    Maybe I should have let the damper cure longer before trying to apply the white paint for the numbers, but I needed to get-er-dun so I went for it.

    I found this online and it's somewhat interesting:

    http://www.engineeringtoolbox.com/ch...oxy-d_786.html

    It says that "epoxy" is attacked by acetone, which I found takes DPLF off easily. I checked the white rattle can paint I used and it says it contains acetone, toluene, and xylene. I checked another one I have and it says it contains toluene and xylene, but doesn't mention acetone. Notice the chart says that "epoxy" is supposed to have "fair" resistance to toluene and "excellent" resistance to xylene. I had some xylene sitting on the shelf and I probably should have used that instead. I also tried butyl acetate (cleaner for Cerakote) and although it didn't take the DPLF off, it did remove the sheen...the chart says it has "good" resistance to it. I think I'm going to do some testing to see if DPLF resists xylene or not just for my information.

    I'm glad epoxy is resistant to "beer".

    I am going to use the SPI epoxy on the damper when it gets here. But I'm still going to test it's resistance to these solvents before using them.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

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