Laminating Epoxy didn't cure?!?

[JSW]

I used this Specialty Resin & Chemical Epox-It 80 Clear Epoxy Resin from Amazon to coat the balsa nosecones/boat-tail of my ASP 29mm WAC Corporal.

Brand new bottles. I've never used this brand/kind of epoxy before. It's supposed to cure in 40 hours. After almost 2 weeks in a hot garage it is still tacky. I'm not sure why? I believe I followed the directions and used equal parts of the epoxy components. I believe I mixed thoroughly. I'd think the heat of the garage should be good for curing.

Regardless of why this happened,... now I need to fix.

Any recommendations on how to correct this? Not sure if it's possible to sand it off? Could I cover with a new epoxy coat (using a different epoxy)?

Any advice would be appreciated.

 

[mikec]

Wipe it down with some alcohol and see if it's still sticky.

Did the stuff in your mixing cup cure OK?

I've never used this stuff either, it's not really laminating epoxy, it's intended for coating. It may be especially sensitive to suboptimal mixing or mix ratio: https://specialtyresin.com/content/pdf/SRC_Inst_Epox-It-80.pdf

 

[JSW]

Mixing cup had the same tacky result. I mixed pretty good - just as good as I do with other epoxies - but as a test I can repeat and put some dye in it,... see if it still has a cure problem.

I'll try the alcohol wipe.

Thanks!

 

[techrat]

Acetone (nail polish remover) will also clean up epoxy. If the alcohol doesn't work, you can get nail polish remover at a dollar store or Walgreens/CVS/Duane Reade.

 

[Back_at_it]

I've seen a tacky surface on some epoxies after they are cured. I've wet sanded with 400 grit a few times to remove that outer layer.

If you find that it it more than just the outer layer that is soft, you will probably need to sand it off and start over. I'm not sure I'd try applying additional epoxy over the old stuff.

 

[JSW]

i used alcohol, nail polish remover, and goof-off,... for the most part it came off with some scrubbing. i'm going to let it dry and sand. then test the laminating epoxy and decide what to do next.

i wouldn't have normally "painted" the balsa components with epoxy, but the WAC corporal booster balsa nose cone is going to take some heat from the main motor. Thought it might be good to give it a bit more protection. once i saw how nice, shiny, and smooth it looked,... decided to use the leftover mixed epoxy to give the main nose cone and boat-tail the same treatment. thank god i didn't do the fins!

thanks for the info.

 

[Back_at_it]

i used alcohol, nail polish remover, and goof-off,... for the most part it came off with some scrubbing. i'm going to let it dry and sand. then test the laminating epoxy and decide what to do next.

i wouldn't have normally "painted" the balsa components with epoxy, but the WAC corporal booster balsa nose cone is going to take some heat from the main motor. Thought it might be good to give it a bit more protection. once i saw how nice, shiny, and smooth it looked,... decided to use the leftover mixed epoxy to give the main nose cone and boat-tail the same treatment. thank god i didn't do the fins!

thanks for the info.

There's nothing wrong with using epoxy as a top coat. I've done it on a number of builds and it works out perfectly when it cures correctly.

The first pic is my F-32. The entire rocket was coated after assembly to strengthen the balsa and tubes. The end result was a finish that required almost no sanding to make perfectly smooth.

The second pic is the fins of my Mega Mosquito. They were coated using T-88 epoxy to harden the fins and make them smooth.

 

[RokitFlyr]

There's nothing wrong with using epoxy as a top coat. I've done it on a number of builds and it works out perfectly when it cures correctly.

The first pic is my F-32. The entire rocket was coated after assembly to strengthen the balsa and tubes. The end result was a finish that required almost no sanding to make perfectly smooth.

The second pic is the fins of my Mega Mosquito. They were coated using T-88 epoxy to harden the fins and make them smooth.

Not trying to be a D@#$, but how does this help the OP fix/solve the problem? I missed the part of "show me yours" I guess.. When using a new adhesive product or process, it's best to do a small test run on some scrap.
Depending on how soft the fillets are, a grout scraping tool works for removing them. Don't ask how I know.
Looks like you're on the right track tho.
Good luck, show use the results, please.

Mark

 

[Back_at_it]

Not trying to be a D@#$, but how does this help the OP fix/solve the problem? I missed the part of "show me yours" I guess.. When using a new adhesive product or process, it's best to do a small test run on some scrap.
Depending on how soft the fillets are, a grout scraping tool works for removing them. Don't ask how I know.
Looks like you're on the right track tho.
Good luck, show use the results, please.

Mark

The OP mentioned that he wouldn't have normally painted the parts with epoxy then regretted do so with the comment "thank god I didn't do the fins".

Just letting them know this is a common practice and there is nothing wrong with doing so in the future with good results. Since a PIC is worth a thousand words I included a couple to show the results.

 

[Grog6]

Epoxies are touchy sometimes. Humidity can make them blush, which is that tacky surface. Polyvinyl alcohol can help prevent that. depends on chemistry of your epoxy. Use a scale, not a volume measurement, it will be more repeatable. I use this stuff:
https://www.3m.com/3M/en_US/p/d/b40066554/We used these for epoxies and rtv's of various types. they sell refillable syringe type dispensers of varying ratios, as well. I have an assortment, 10:1, 2/1, 1:1, and so on. The mixing nozzles take the variability out of the mixing.

 

[86mustang408w]

I have this issue too with a rocket I built and the epoxy didnt cure, well from it standing vertical on the peg board I made it all ran to the bottom of the fins, lol...

 

[Donnager]

Only counsel on this that I have is be certain your epoxy is completely mixed. If it takes a minute of stirring to make it clear, double the stir time.

Be careful about unmixed resin residue on the sides if you are mixing in a cup. If I am covering a good area, I've been known to mix in one cup, pour the mixed epoxy into another cup, re-mix and then apply, just to be sure I have no unmixed resin boogers that can creep up on me later.

 

[David Schwantz]

Do NOT use the same epoxy again. Throw it away.