Using epoxy without topcoat?

[chevynut]

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.

[LEE T]

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.

[chevynut]

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.

[Rick_L]

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.

[chevynut]

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.

[LEE T]

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????

[chevynut]

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.

[55 Rescue Dog]

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.

[Rick_L]

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.

[chevynut]

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/chemical-resistance-epoxy-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.

[chevynut]

Well I found out that Xylene does attack DPLF so that's out. It's not as aggressive as acetone, but DPLF does not have "excellent" resistance to it like an epoxy is supposed to have.

[MP&C]

I had primed some motorcycle tanks once and forgot about cleaning the inside for sealing the inside (customer request). This involves shaking the tank with a section of sash chain and MEK solution inside. Splashed MEK all down the outside, guide coat RUNS off the side with the MEK. Never touched the epoxy. This was House of Kolor KP2.

[chevynut]

Anyone know how long it takes for SPI epoxy to cure to the point that it's chemical resistant? Two hours after I sprayed it acetone took it off, but I know that's not long enough to cure. What solvents is it resistant to? I need to spray the timing numbers on my damper with white paint and wipe the rest off with something that won't attack the SPI epoxy.

[LEE T]

Call the owner of SPI, he is available almost anytime 7 days except after 5PM on Wednesdays. He has all the answers and will talk to you as long as it takes to fully answer all your questions.
404-307-9740

[Tabasco]

Use white latex exterior house paint on the numbers. Wipe over with a damp rag. Problem solved.

[chevynut]

Tabasco, that's not a bad idea. :)

[chevynut]

After 24 hours I found that acetone still takes the SPI epoxy off, and so does lacquer thinner. In fact the lacquer thinner attacks it more readily than the acetone. I read on a SPI forum that the epoxy takes 7 days to fully cure.

[Rick_L]

Lacquer thinner is a lot more aggressive than acetone in my experience. Just in general.

It's not clear what you're up to here other than painting the marks on your balancer mentioned in your other thread. Epoxy does take a while to cure fully, even if you can touch it, paint over it, etc. prior to full cure. In fact I think that's intentional, as a "compatible" topcoat will have a chemical bond to it, specifically because of that cure time.

I think Tabasco's simple solution will work - or maybe things will change if you wait a week.

[chevynut]

Part of what I'm interested in is how good the solvent resistance is for SPI epoxy in general. The specific task right now is the damper markings. I want to make them a lot more visible than they are. The TDC mark is easy, but the other marks are hard to see.

[mech393]

I have used por-15 on my under carriage but also can be painted chassis black so the sun won't damage it but chemicals won't harm it and you can beat it with a hammer and it won't chip but once its on there its not coming off. it also can be brushed on and when it dries it becomes smooth no brush marks the only thing bad about it is you must use it in a ventilated area and if you get it on your hands it not coming off.

[chevynut]

I have used por-15 on my under carriage but also can be painted chassis black so the sun won't damage it but chemicals won't harm it and you can beat it with a hammer and it won't chip but once its on there its not coming off. it also can be brushed on and when it dries it becomes smooth no brush marks the only thing bad about it is you must use it in a ventilated area and if you get it on your hands it not coming off.

I've heard from several sources that POR-15 doesn't stick worth a damn to clean metal, and I refuse to paint over rust when I can remove it. I used a similar product, Rust Bullet, inside my doors at the very bottom after cleaning as good as I could. Both are MCUs (moisture curing urethanes).

[LEE T]

After 24 hours I found that acetone still takes the SPI epoxy off, and so does lacquer thinner. In fact the lacquer thinner attacks it more readily than the acetone. I read on a SPI forum that the epoxy takes 7 days to fully cure.
I'm not sure about the cure time for chemical resistance, but 7 days is the safe recoat window, full cure is much later than that.

[Rick_L]

I have seen POR15 come off in sheets. So much for chip resistance and never lifting.

Toxicity, never comes off your hands, etc. plus it doesn't stick anyway are my reasons for never using it. Spray it and it's even worse. The overspray sometimes sticks better than what you intended to have a coating on.

[mech393]

por15 won't stick to smooth metal just like paint you have to score it, the paint works best on sand blasted metal ive had it on my Camaro for over eight years and its there and ive steam cleaned it many times so if the paint has come off in sheets then the metal wasn't prepped right.