This subject was brought up on another board (ABS) and i wanted to run it by some of you here.A guy was concerned because he was able to wipe his cured PPG DP90LF off with a thinner soaked rag. it was suggested that his,catalyst was old, bad batch, mixed wrong ect. Well a few more guys did the rag test and said it was wiping off. One guy had it wipe off with another brand (RM?) Now i tested my two week old DP90LF and when rubbing a thinner soaked rag, it turns the rag black and the primer gets soft enough that i could scratch it off with My fingernail. Is this normal? Is this from all the 'reformulation' going on. Barry will SPI Epoxy soften with thinner?

To answer your last question, No. after setting overnight.

Don't confuse dusting of color with wiping off.
With a cured primer or epoxy if you hit it with thinner you may get a smudge of color and that is normal.

If the product is softening it can only be weak activator, improper mixing, cold metal, excessive coats (retarding the cure) or applied over an unneutralized acid or epoxy has not cured long enough.

Some epoxies cure out faster than others and with that in mind perhaps a 2-3 day set time would be in order before wiping with thinner.

This is all I can think of that can cause the epoxy to whip off.

No experience with it wiping off.

But it WILL lift along a sanded edge. As a matter of fact I have had problems spraying DP over sanded DP many times. I have learned how to spray it a little better and have not had it happen lately.

So I know thinner will lift DP.

Rich

Epoxy will not wipe off after it's reached full cure. Fully cured epoxy will however swell some if subjected to solvent for a long period of time, all 2K primers seem to do this, urethanes, and also polyesters. Example:I've soaked primer guns in lacquer thinner for weeks that had old cured epoxy on them and all the lacquer thinner will do is slightly swell and soften the primer, the primer will never be soluable again after it's reached full cure. If the primer is washing off with solvent it hasn't cured. Epoxy is slow drying IMO, but very very durable after full cure. If it's still soluable after 2-3 days there is definately something wrong with the product, temperature, or application. The thicker it's applied the longer it takes to cure, leave some mixed epoxy out in a mix cup and you'll see the more product in the cup the longer it takes to cure.

Well two different brands of epoxy are wiping off after full cure for about six or seven guys who are in different states and dont even know each other. Mine didnt wip all the way off,i rubbed it and it was coming off on the rag.It softened and i'm sure if i continued to rub it would have gone down to the metal. It was sprayed about two weeks ago. If you have some epoxy on something try it out.

Well i just tried rubbing thinner on a panel that had U-tech epoxy on it for a good six months.Rag turned black,primer got soft and i scratched it with my fingernail down to bare metal. Next test. I have a decklid that has 'the old' dp40 on it for at least three years,maybe longer.Same result,rag turned green, scratched it down to bare metal. I think the result will be the same no matter what brand.

I don't know if it's the same thing but I used SPI epoxy for my engine bay and frame parts and got alot of urethane over spray on it. I then took acetone on a rag and removed all of the cured overspray and it did not soften the SPI, no black came off on the rag. I don't remember if I tried lacquer thinner or not but I'll try it later to see. I'm a believer in the SPI epoxy, haven't used the urethanes yet.

In my experience the DPLF epoxy primer will definitly wipe off with lacquer thinner all the way to the metal, even after three or four days. The SPI epoxy primer is not affected by lacquer thinner after three or four days. This is one of the reasons I don't use PPG's DP anymore. In fairness to the DP product I can't say if it will wipe off after 7 or more days because I haven't tested it.
Jim

[QUOTE=shoddy_f-body]Well i just tried rubbing thinner on a panel that had U-tech epoxy on it for a good six months.Rag turned black,primer got soft and i scratched it with my fingernail down to bare metal.
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I can assure you the U-Tech never did this.
Maybe since Sikkens bought them in 2001 its been changed.???

What I'm seeing written just blows my mind, I'm all confused.

This whole thread did not seem to make sense so I decided to try it on my own. I am finishing a car that is primed and sealed exclusively in DP90 and DP50LF

I have trunk that was done and sealed at one time but has sat in the corner and got scuff. So it really needs blocked out again. It has DP90 on it and is about 3 years old.

So I got out a clean rag and some thinner and started wiping down an area. The rage became dark so I went to a clean rag, it became black. With continued rubbing it began to soften. I dont know how long it would take to get through the black with a rag, but I can say after doing this with the rag my fingernail took it down to bare metal.

So I have to concur with the above thinner softens DP comments.

Rich

Another guy on ABS said it happened to him with RM epoxy also.So i wound'nt say its just a PPG problem.

Cured Epoxy will swell and soften but I've never seen it turn soluable. Self etch primer on the other hand will wash off whenever you want and will be forever soluable just like lacquer primer. Urethanes and polyester products will also swell and soften if exposed to lacquer thinner for a long time but won't wash off/become soluable. For the epoxy to wash off after full cure doesn't make any sense. I've got some primered parts in the shop that I'll try washing with thinner tomorrow, the epoxy on these is three months old. Bob

"Doesnt make sense" to me either

Like I said, I dont know how long it would take to rub through but after 60 seconds of rubbing, it was soft enough finger nail would take it off.

I told my Jobber to ask PPG on their opinion. Be interesting to see what they have to say.

I have experienced the same thing with PPG DPLF74. I had applied it to a four piece Rootlieb steel 34 Ford hood probably a year ago to keep it from rusting in my garage as I worked on finishing the car. The DPLF74 and hardener were fresh from the local jobber and applied the same day as purchased. A year later I discoverd the red PPG epoxy primer will wipe off with a few swipes of a lacquer soaked rag . I removed all of it and applied SPI's self etching epoxy primer and have had no such problems. Considering what I paid for a quart of DPLF74 it really gives me the rosie's.

Vince

I've been using Kirker EP611, sprayed some on a table top to empty the gun about 10 days ago. Took laquer thinner and rubbed the crap out of it this morning and the rag turned a little gray and now the top is really clean No softening at all and couldn't scrape through at all with a fingernail.... I would not have been happy if thinner would take it off!