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onebadmerc 11-20-2006 07:34 PM

Having problem with epoxy primer......
Last week I stripped my hood and used naval jelly hood to get rid of the rust and crow checked paint.Thursday I finished cleaning up the hood and sprayed it with two coats of Omni MP172 Epoxy primer. The day was about 70-75 degrees when I sprayed the primer. After spraying the primer I let the hood set out in the sun for about 5 hours. Fast forward, five days later the primer on the hood has hardened to the touch but still will scratch with a fingernail. I figured I would DA it with 180 and fix the dings and dents. When I tried to DA the hood it kept loading up the paper and throwing little balls of primer. I finally got the hood sanded down real well and figured maybe it would be ok to fix the dents. After applying the filler, I decided to scrape off a few of the filler goobers with a scraper. When I started to do this the filler came off but it took the primer with it. I know something is wrong with what I did and know this is not going to work. Do I need to strip the hood back down and start from scratch or is this normal? This is the first time I have tried epoxy primer, all I can say is I am really disappointed with it. Here is the details for everybody. The nights were cold and I didn't keep my garage warm. Number two is, before I sprayed the epoxy primer I sanded the hood down with 120 grit on a DA. I never have used epoxy primer before, I was trained old school and learned to fix dents on bare metal and then prime it with a 2K primer. I have never had any problems with my old ways, and figured I would try the new school method. I know something is wrong , so let me know what I did wrong and what I need to do to remedy this problem.

colormecrazy 11-20-2006 07:58 PM

It sounds to me like one of two things. A. it has not had long enough at a high enough temperature to cure yet. or B. you did not clean the hood well enough before you sprayed it.

Naval jelly is nasty stuff, it works well, yes, but, it is a real pain to get it all off the panel. And, MP172 has a 1 week window at 75 degrees. But, because you say it is not sticking when you put filler on it tell's me, You didn't get it clean. I'd say, sand it all back off, clean very thoroughly with water (yes, water) then wax and grease remover, then try again. Remember that you can wipe your filler right over it (within a week) without sanding. And I've used MP172 several times and it works.

onebadmerc 11-20-2006 08:11 PM

After I used the naval jelly I washed it with water, I then wiped it down with lacquer thinner. I then let the hood dry and then sanded it down with 120 grit on a DA. I then used a final wash before I primed it. I don't think it was dirty, but it probably was. I was figuring it was more of a temperature issue, since my garage was not maintained at 75 degrees for the last week.

kenseth17 11-20-2006 08:11 PM

Either that epoxy just wasn't cured yet (epoxy is a slow curing product) or you mixed wrong/bad can of activator, or the epoxy went dormant cause wasn't kept above 60 long enough. Isn't the cure time on omni longer then 5 days, I don't know how much placing in the sun would shorten cure time. Or its not adhering to the navel jellyed surface. I'll let others see what they think, but several things could be the problems. Most Epoxys are not normally easy sanding, and has a slow cure time, so that could be why it is was balling up your paper. It will look like its not adhering well/scratching until it has time to cure. Wetsanding probably would have worked better though. But for the ones that say you must sand epoxy for filler to adhere, then why when he scraped the filler did the epoxy go with it, wouldn't the filler just pop off from the epoxy? But my opinion is the epoxy itself wasn't fully cured or it couldn't adhere to what was under it.

kenseth17 11-20-2006 08:17 PM

Lacquer primer isn't really cleaning the surface. It flashes off too quick and you can't really doesn't get rid of the contaminants. You need a wax and grease remover which is what is designed for the purpose. W&G remover will float contaminants, and say wet longer allowing you to follow the wiping it on with another clean rag before it has dryed.

onebadmerc 11-20-2006 08:28 PM

I used PPG DX330 wax and grease remover before I shot the primer. I used the laquer thinner after I washed the hood with water. There was a day difference between washing the hood with water, laquer thinner and sanding it and wiping it down with DX330 and priming it.

colormecrazy 11-20-2006 08:42 PM

DX330 is way way slow. That could actually be your problem. If you didn't get it all off. :pain: As Kenseth said, MP172 doesn't sand real good anyway, but, It does stick.

BarryK 11-21-2006 04:20 AM

Its a 100% temperature issue.

Now being epoxy and not getting a chance to cure it will need more heat and for a lot longer period of time to finish curing out then a say a 2K primer painted the same time.

Past experience with these kind of problems I will suggest you need the panel exposed to around 140 degrees for four-five hours or a couple of weeks (minimum) at 75 degrees and up.

Here is something that could have contributed to your problem also.
Were having a cold spell here and I keep the one garage heated at all times due to the amount of paint I have in the garage.
The temp is set at 63 degrees because I'm not working on anything right now.
I just now took the laser reader and a gallon of paint on the work bench gave a reading of 63 degrees, a gallon in a box on the cement floor red 55 degrees and a new fender setting on the floor read 53 degrees.
If you have had the epoxy setting there for a while and its 55 degrees or less it is just plain not going to kick.

onebadmerc 11-21-2006 07:57 AM

Thanks for all the replies and help on this. This was my first time using epoxy primer, all I can say if you don't screw up you are not learning anything. My plan of attack is to take the hood back down to bare metal and start over, hopefully everything goes well this time around.

Bee4Me 11-21-2006 10:06 AM

This issue came up awhile back I recall with the Omni epoxy and it being "soft" as well as lacquer thinner wiping it off.
Nature of that beast I believe.
Anybody bookmark that one?

crashtech 11-23-2006 12:20 PM

Epoxy is THE best thing for coating bare steel, but as far as cure rate goes, it can be a bit unforgiving. I would suggest that everyone doing refinish work in colder weather buy an infrared thermometer. I have one now and couldn't live without it during the winter. It's really important to keep metal temps above 60°F, As Barry says you can go down to 55° but in my experience the cure rate is VERY slow below 60°, plus there is always a margin for error, and as far as I know, somewhere in the mid 50's, catalyzing of the material just plain STOPS.

baddbob 11-23-2006 12:52 PM

Yup I agree it's either a temperature issue before and after spraying, old epoxy catalyst that has gone bad or a combination of the two. Your cleaning methods should have worked just fine and 120 grit scratches should have provided enough texture although 80 grit would have been better. I think it's time you shoot a test panel in good temperatures with good cure temps and see if the primer locks up and hardens good.

haism007 06-06-2008 06:41 AM

hello every one


STEP 1: Clean surface with soap and water to remove water soluble residue.
STEP 2: Clean surface with a wax and grease remover (PPG DX 330).
STEP 3: Hand sand hood to finished surface with 220 grit sand paper.
STEP 4: Clean surface with a wax and grease remover (PPG DX 330) and then apply a fast evaporating cleaner (PPG DX 220).
STEP 5: Apply the epoxy primer coat (PPG DP Series)*.
STEP 6: Clean surface with a wax and grease remover (PPG DX 330).
STEP 7: Lightly sand the surface with 220 grit sand paper.
STEP 8: Clean surface with a wax and grease remover (PPG DX 330) and then apply a fast evaporating cleaner (PPG DX 220).
STEP 9: Apply primer surfacer coat (PPG K36*.
STEP 10: Finish sand the surface with 400 grit sand paper, clean surface with a wax and grease remover (PPG DX 330) and then apply a fast evaporating cleaner (PPG DX 220).
STEP 11: Apply a coat of epoxy primer as a sealer (PPG DP Series)*. NOTE: To use the epoxy primer as a sealer, follow the mixing instructions provided by the manufacturer.
STEP 12: Apply the basecoat (PPG DBU DeltronŽ)*.
STEP 13: Apply clearcoat (PPG DCU 2020)*.
STEP 14: Polish to desired finish.

goshawks00 08-28-2008 07:40 AM

thanks for the posts all... Not trying to hi-jack thread but seems appropriate to ask... I am about to have my car ( 51 woodie) sandblasted and then it will be epoxied...
Can anyone recommend a good 'fast' drying epoxy so I don't run into these issues?
Thanks guys all are making the site a big bonus to me and I really appreciate you.

shine 08-28-2008 08:18 AM

220 is too fine for epoxy in my opinion. i 80 grit everything before epoxy.

temp is the leading cause for all types of paint failures .
i would move up to a better quality epoxy if it were me.

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