I recently undertook a repair using epoxy in less than ideal conditions(garage in New jersey) and the resin never fully hardened. I have had the board inside for 2 days and it is still tacky. Do I have any options to get the resin so it can be sanded(I think the mix ratio was correct) or do I have to redo the repair?
your probly best off redoing the repair
just scrape it out and start over
be carefull mixing small amounts of epoxy
From one Jersey guy to another: do the re-do in the house at room temp. Smell is insignificant. Open a window for a bit of ventilation if you must.
If it’s still tacky your ratio must have been off… too much resin, not enough hardener. If only parts are tacky, and other parts are cured, it’s a mixing issue.
It’s a re-do.
Don’t even think about doing it in your garage for the next several days… it’s gonna get bluenut cold. Bring your materials and board in the house and let them warm up. Lay down some newspaper, mix small volumes by weight if you can, and try again.
I’ve had the epoxy stay gummy if there is too much hardener in the ratio. For small batches I like using a digital scale.
There could be degrees of “too much hardener,” but my experience has been that too much hardener leaves a soft or rubbery end product. Too much resin never fully cures.
I feel a weight vs volume discussion coming 
(I’m with the weightwatchers :P)
Scale 100%!! I’ve done by volume and had the batch come out questionable. With the scale, perfect every time. There’s an old thread about this(probably a million of them).
For small batches you can't beat measuring syringes. You can get them at the local drug store. You can keep re-using them so long as you always use the same one on the hardener and the same one in the resin and you keep them clean. The biggest problem with measuring with cups is you can easily be off quite a bit by volume and still be within a fraction of the measuring line on the side of the cup. Its just too hard to be accurate with cups. Syringes eliminate this problem.
NO!! mix by volume. Epoxy resin is heavier than the hardner. So unless you are doing a 45:55 ratio, the volume thing is a lot easier.
If you have to make a small batch...get a small jar. measure out 2 parts of water...draw a line...then pour one part wateron top of that: draw the line. Now dry out the cup and do it with epoxy...it takes about 20 seconds start to finish.
It's easy, don't make it more difficult that it has to be. Also RR resin is a lot more forgiving than other brands. The big deal is the temp of the room. Low temps can screw the whole thig..but then that's where a heat gun comes in handy if you know how to use it. (and I said if you know how to use it, otherwise you are going to create delam, or volcanos)
Do it by weight, which will requrie a different ratio than volume. The manufacturer will supply this for you. Don’t try to mix 3 fricking grams of the stuff. If you’re that broke, sell your surfboard and get a job. You have no business surfing if you can’t afford a few grams of epoxy. If weight ratio is unavailable, use the syringe thing. Also, nearly all this stuff is intended for use at or near 75F. Make sure all of both parts are mixed thoroughly (none hanging out in the corners/sides of your mixing container). Mix until all striations gone, and then some.
Where in his post did he specify he was using a 2:1 by volume epoxy? They make ones with other ratios, you know? Besides, small batches are always difficult, especially when both the drawing of and filling to the line are error prone. Sorry, but you’re not helping the guy much by your “answer”. Others here have some good ideas, particularly the syringes for small amounts by volume. Carry on.
I’ve never had a problem with epoxy not curing.I use to mix by volume,but after mixing by weight and seeing each drop of resin register on the scale its a no brainer.
Having done it with a scale, measuring cups, and eye-balling it with paper cups, I’ve never really had any issues. Not counting spreading it out and having a pool of sweat pour out of my nitrile glove onto the board during the scorching Florida summer in my garage. I suppose foam hides water marks, but balsa is not very forgiving.