varnish-epoxy issues again!

[Chuckles]

Some of you may remember that last fall I had a lot of trouble with minwax spar urethane that was not curing over epoxy on my galley hatch. The epoxy was only a week or so old so I thought there might be some issues there. I ended up wiping off the sticky finish with mineral spirits and sanding off the rest. then applied a new coat of epoxy.

Well, more than 7 months later I finally got back to it. I scuff sanded the hatch and wiped it down with mineral spirits. This time I used Cabots satin spar varnish. No problems at all on the interior surfaces (no epoxy) or the small test area with epoxy so I brushed on a coat. Three days later about 95% of the surface cured just fine... the other 5% remained tacky .

I am at my wits end! The spots that didn't cure were an area where there was a run in the epoxy that required more sanding and some edges where I may have sanded deeper into the epoxy. Today I wiped and sanded until I got all the bad varnish off then wiped everything down with mineral spirits again.

Has anyone had a problem like this? What should I be using to wipe down the epoxy to get rid of contaminants? I tried acetone but it softens the cured varnish. Should I use alcohol, mineral spirits (paint thinner), or other solvent? I really need to figure this out before I tackle the whole trailer. Any help would be appreciated.

Chuck

[tony.latham]

Good grief, I do recall this trouble. Thankfully, I have not had this problem. I'm sure you've Googled it, but typically it's an "amine blush" issue with the epoxy and that stuff is water soluble -acetone etc won't touch it.

Have you let it sit in the sun? There's something about varnish and UV rays. Wash that spot down with soapy water, rinse, and try an unthinned spot test with your varnish and park it in the sun for a couple of days. Two-bits it hardens up.

Easy for me to say.

Tony

[Capt.todd]

Hi Chuck
What kind of Epoxy are you using? Amine blush is the first thing that comes to mind, and like tony said it's water soluble. I work with A LOT of varnish and epoxy.....mainly epifanes for the varnish and west system and MAS for epoxy and have never had any comparability issues with those 3. Another option might be either Bristol Finish (acrylic urethane) or any 2 part auto clear over the epoxy, these both work quite well on our boats in SW Florida. Let us know what you find out.

Todd

[doug hodder]

How well did you mix your resin and catalyst, and were they correctly dispensed? I've never had an amine blush on my epoxies. Doug

[Chuckles]

Thanks for the responses. I had some computer problems the last few days but I'm back now.

I used RAKA UV inhibited epoxy and Cabots spar varnish. I cleaned the dickens out of it with alcohol and paint thinner then gave it another coat of spar varnish. This time it cured just fine. I did a little reading and it looks like the proper course of action from here on out will be to scuff sand then wash with soap and water then let it dry and wipe with thinner before putting spar varnish on the body.

The first coats of epoxy over glass were put on in an air conditioned workshop. I think I did three coats (one per day) and never had any problems except a few minor bubbles so I don't think mixing was a problem. Once assembled I glassed the roof and ends then added another coat or two on the whole camper. When I did this I was in a very hot and humid garage and there was a lot of cloudy areas under/between the coats of epoxy when it was all done. I probably didn't do myself any favors by rushing the camper into use on a rainy day when the last coat of epoxy was only 36 hours old.

Right now it looks good in the shade but in the sun you can really see the cloudy spots. I don't think there is anything I can do about it now... hopefully I can get through the varnishing without any other problems though.

Right now I'm working on the galley cabinets. I'll post some pics when I'm done

Chuck