Having a finish issue on my most recent build. I have been applying multiple thin coats of finish to get my end results. Using ProKote. On the last and final coat I applied as usual. I cleaned my mixing cup with denatured alcohol and mixed as usual. Equal proportions of both. The issue is that after I applied the last coat I rechecked everything and all looked good. I let dry overnight. When I came to check the next morning the finish had separated from the previous coat and fish eyed real bad. Is this because the previous coat had cured too long and the new finish wouldn't adhere to it? It wasn't even 24hrs between coats, but it was in a moderately warm environment. Thanks for any advice.

Possibly. Once epoxy cures to a certain extent you're applying the next actual coat onto a surface that will tend to repel anything placed upon it. If the temperature was warm enough, then the cure time was accelerated to the point that this happened in only 24 hours.

There is another possibility, however, and this concerns wiping the inside of your mixing cup with alcohol. This is never a good idea as many solvents contain fragrances and the like that can contaminate an epoxy or similar finish. If you feel the need to do that, always rinse the cup with water afterwards. Better yet, use plastic mixing cups and supply a fresh one each time out.

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Thanks Tom. I've never heard of Denatured alcohol having fragrances in it. Not saying that it doesn't, but it sure doesn't smell like it. I see people on here all the time talking about wiping down the previous coat of finish after drying to remove any oils from your fingers that may have gotten on there. Wouldn't this cause the same issue? I also see people that have thinned their finish with denatured alcohol. Wouldn't that cause an issue as well? Sorry for the questions, but I'm fairly new at it, and am trying to get the root of the problem. If applying multiple coats would it be better to lightly scuff the previous application with sandpaper before applying the next coat? Thanks again.

People write and do all sorts of stuff and often get away with it. The fact is, any good chemist will tell you that a solvent wipe should never be the last step in any surface preparation technique. Be sure to read the surface preparation article in the online library here.

The best way to keep finger and hand oils off your wraps is not to get any on there to begin with. There is never any need to handle the thread with your fingers once the wrap has been made. And if your hands and fingers are washed and cleaned, some light handling isn't going to harm anything. I think sometimes that in their efforts to "clean" things, builders often introduce more problems than what they were trying to correct.

I don't think you need to go so far as to sand anything between coats/applications. Generally you can allow a couple or even three days between applications and still expect good results if applying more epoxy after that much time. Scouring a previous application of epoxy, with fine grey Scotchbrite, is really only recommended if some time has passed between applications, say more than a week or so.

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x1000 on never using any solvent on a finish before adding another coat.

Also, never use solvent to clean out a mixing cup. Use a new plastic cup. Too many issues with a solvent causing a problem on an ensuing coat.

Be safe

Lesson learned......The hard way.

I never mix any type of epoxy in any kind of plastic container, I use aluminum cans-cups or foil. Certain types of plastics can interact with the epoxy and contaminate the epoxy. If bonding grips and reel seats, this contamination may not be detrimental, if it is used in a finish application the contamination may cause noticeable cosmetic effects. If you must use plastic mixing cups make absolutely sure that the plastic cup will not interact with the epoxy used.

John

I use the plastic sample cups that are commonly used in Grocery stores and Delis. Very inexpensive and have never had any issues.

Be safe

I buy my plastic cups from a local food distributor. I've never had a problem with them. 200 small cups @ $5.00

I was using the small medicine cups and didn't have any issues the first 2 coats and did the same thing on those 2 coats with no issues. I'm just thinking the finish had set too much and was too smooth for the other coat to adhere to. Is this possible?

I have had the same problem before and I believe it was because I had touched some of the wraps in between coats of epoxy. Not positive that was the reason but that might be something to look out for. Aside from making sure I don't touch anything I started doing the coats as close together as possible while the previous application is still a little tacky.

If the finish has cured to a certain point, it will indeed attempt to repel further applications. I would need to see a photo to determine if you're dealing with contamination or simple repelling of a subsequent epoxy application. They are quite different in appearance.

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Thanks Tom. I'll try and send you a photo soon. Getting ready to head to The Henry's Fork in Idaho this weekend. May have to send it when I return. Thanks again!

I use prokote all the time, you have to wait 24 hours before you put the next finish. You may have not let it cure enough.

Gabriele, why do you have to wait 24 hours? I waited 21, and I was in a warm environment? Just curious.

I always follow the manufactured recommendations, the instructions say recoat after 24 hrs.

A lot of times that does not work
You have to Experiment and find how you can alter and make things -- BETTER

Bill - willierods.com

Just saying cause I use prokote and its amazing stuff. Wish it would cure a bit quicker.