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View Full Version : Epoxy has cured hard but left a tacky surface???



Larks
06-16-2014, 03:18 AM
I can't say that I've come across this before...I've used International Epiglass resin and their standard hardener to glue up all of the planks on my stitch and glue Thames Skiff.

By this morning it had cured hard but felt tacky to touch when I was heading off to work and this afternoon it still feels tacky/sticky to touch, although it is indeed rock hard throughout.

Has anyone had this experience with this or other epoxy resin systems?

Weather has been dry and temperature ranges since laying down the epoxy have been from 6degC/42degF last night to about 16degC/60degF (probably even a bit warmer where the hull is sitting in the garage behind the roller door that would have copped the morning sun).

slug
06-16-2014, 03:38 AM
epiglass is my favorite resin. Low viscosity, almost spreads like paint. Never had any problems, cure time is predictable , only normal blush.

One problem with epiglass is the 4 to one mix ratio.....perhaps you measured or mixed incorrectly

ask international...perhaps there is a defect in the resin.

Larks
06-16-2014, 03:46 AM
slug the HT9000 that I have specifies a 3:1 mix and good for temps between 10degC and 35degC. I know there is a 4:1 mix kit but this one definitely specifies 3:1 (it was the first thing I rechecked when I came home and found it still tacky)
http://www.yachtpaint.com/LiteratureCentre/epiglass_ht9000_manual_ap_eng.pdf

It may be a temp' thing but I'd be surprised as it was layed at about 15-18degC and, other than perhaps early this morning when it got down to the minimum, has been over 10degC

Ando56
06-16-2014, 03:48 AM
I can't say that I've come across this before...I've used International Epiglass resin and their standard hardener to glue up all of the planks on my stitch and glue Thames Skiff.

By this morning it had cured hard but felt tacky to touch when I was heading off to work and this afternoon it still feels tacky/sticky to touch, although it is indeed rock hard throughout.

Has anyone had this experience with this or other epoxy resin systems?

Weather has been dry and temperature ranges since laying down the epoxy have been from 6degC/42degF last night to about 16degC/60degF (probably even a bit warmer where the hull is sitting in the garage behind the roller door that would have copped the morning sun).

I am using West System for building my boat and did the transom the other day when it was about 10C. Next morning there were practically beads of tacky stuff but the glass itself had set hard. I put it down to a good dose of amine blush due to the colder weather and gave it a wash. Seems fine now. However I'm no expert and on a massive learning curve.

Ken

slug
06-16-2014, 03:58 AM
Possible they have different epiglass hardeners and reisn

You can try to raise the heat and cook the epoxy

blush could be the problem


If you are confident of the mixing Id call international and asked what happened.

RFNK
06-16-2014, 04:05 AM
My friend David had this happen with another brand of epoxy with a 4:1 mix ratio, I think. Like you, he's very careful with mixing and the reason remains a mystery. I only use 2:1 mixes because I'm too lazy and sloppy to bother with complicated systems and I've never had a problem like this. I'd also recommend calling International and discussing it with them. Very annoying!

Rick

George Ray
06-16-2014, 04:26 AM
Blush/Bloom: In addition to temp and humidity, CO2 as in a combustion byproduct from a heater is a factor
Have a look at Dow Chemicals discussion of Blush/Bloom and see if it fits ( Pretty darn readable for a tech paper ).
(note: What was the relative humidity at the coldest point of the cure cycle?)

http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_00cb/0901b803800cb78d.pdf?filepath=/296-01656.pdf&fromPage=GetDoc

pipefitter
06-16-2014, 04:31 AM
If it passes the fingernail test, it's likely due to the cool temps, regardless whether the epoxy was designed for it or not. Is why most will recommend waiting a week before painting or what not. Many resins will have a tacky feel just due to the sheer gloss of it, and you will likely find that it will clog sandpaper until you get the gloss broken, which will also help quicken the full cure.

You may notice that the bits that peel out of the mix pots, or that is left on the brushes, will remain pretty flexible for a few days, and finally really harden up after a week or so. I always keep a spill sample of my resins after the fact so that I may get an idea what changes it is actually going through over time. Even those that claim to be extra flexible, will lose a beneficial amount of that attribute, even over the short term, making such notions a misnomer at best, with regards to actual usefulness in composite boat building.

Larks
06-16-2014, 06:19 AM
Thanks for the comments all. Cumulatively you've given me a cunning plan:

I also keep my mixing trays to check curing (rather than go poking any epoxy on the boat leaving fingerprints and marks when it's still soft), so have these from yesterdays work, all firmly cured but displaying the same tacky surface:

http://i260.photobucket.com/albums/ii11/Larks_01/Larks_01073/DSC_0435_zps8c7f940e.jpg


So, leaving one down in the garage as the control, another has been parked in front of a heater in the bathroom:

http://i260.photobucket.com/albums/ii11/Larks_01/Larks_01073/DSC_0436_zps6af3edf3.jpg

and the other here:

http://i260.photobucket.com/albums/ii11/Larks_01/Larks_01073/DSC_0437_zps6b314469.jpg



And already I can say that the winner is...
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Ken, the warm water and dishwashing liquid scrub has worked immediately and that tub is tack free. (So one guess what I'll be doing after work tomorrow:d).

Thanks again for the responses all.

Doug Schultz
06-16-2014, 09:01 AM
I would have never thought to use the leftover tubs to test this. Or to even keep the tubs. Great thinking.
Glad you found an answer.

Phil Y
06-17-2014, 05:35 PM
Pretty cold in Perth overnight on the weekend, I wouldn't be surprised if your garage got down to 4 or 5. Good that it will wash off.