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Tacky Epoxy Finish

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Jan 14, 2020
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Hi, I just finished posting this about my new epoxy finish rotating holder thing, and I made it all seem like a rainbows and unicorns. A real success. An act of genius. Which of course it was all those things, Except for one thing.
I used system 3 epoxy finish, that takes 2:1 ratio mix. I used a scale and got pretty close to that. I applied it, which was not terribly easy due to the shape of the vase. The rotisserie dryer worked great. I checked after a couple hours figuring it would be dry enough to take of the turner, but it was still tacky. So I check after about 6 hours. Same. I took it off the turner because as you can see from my other post the motor doesn't seem like the most trustworthy thing in the world. I didn't want it burning down my house. In the morning, still dang tacky! What the heck! Does no silver cloud come without a poop lining? It's not that cold here maybe 60 degrees (f) evening and night. Perhaps the mix was off? But seriously, it can't require perfection just to work. so what I read was .7 then I add the other stuff up to 1.1 So that's pretty close. I think?
Anyway, let me know if you know what I did wrong, or if you think I can fix it or if you think it will someday set.
Thanks,
Raif
 
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I recently used an epoxy product to fill a void. The directions called for a 3 day cure time and it took every bit of that and a bit more. With your product what cure time does the directions call for? Also in addition to accurate measures the epoxies seem to require very thorough mixing. The stuff I used called for some number of minutes of mixing by the clock. Just a couple of thoughts.
 

Roger Wiegand

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Most sellers list both the weight and volume ratios for mixing-- you do need to make sure you use the right one.

Depending on the cure time it doesn't surprise me when epoxy feels a bit tacky for several days, especially when it is curing at a low temperature like 60. It is often quite hard even though it feels tacky. Give it a week or two and it will probably be fine. Remember that most reaction rates double with every 10 degC increase in temperature, so it will be half as fast at 60 as at 77 F.
 
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I’ve built several boats using epoxy, and as Chris suggested, the mixing is always by volume, hence metering pumps. I’ve used West System, MAS, and a few off brands, but not System Three, so I can’t swear to that. I agree with Roger that temperature is critical to cure time. Try bringing into a warmer environment. “Rule of thumb” is that when you push your thumbnail into it, it won’t leave an impression when it is sufficiently cured to sand or paint.
 
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West system is very unforgiving if mixing ratios are off. And I think if it’s 3:1 by volume it’s 3.5:1 by weight but don’t quote me on that. A lot of epoxy is by volume hence pump dispensers .

and I think system three epoxy is 2:1 by volume.
 
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I've made a bunch of fishing rods with an epoxy material for the thread coating. Temperature is very important, as Roger said in a much more precise way. My basement is 64-66 degrees year round and when I made a heated box to cure the epoxy, it took much less time at the 78 degrees in the box.
 
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Ok, so I guess I kind of freaked out. It never occurred to me that people would use a finish that could take a couple days to dry :). It seems dry now and I"ll let it sit for while, now that I know it's gonna behave.
The mixture does say 3:1 by VOLUME, or 100:44 by weight, so right there, that's unfortunate. It also says the stuff should BE at 70 degrees before you apply it and that it should be allowed to cure at 70 degrees. Hence the 2 days rather than 6 hours. I'm not a big reader. Actually I just can't see that tiny writing that well and I'm impetuous. But I have learned and my first rotisserie epoxy vase is completed successfully. So I'm pretty happy.
Thanks to everyone for the help pointing me to the culprits. I guess I'm kind of the culprit since it was all in the dang instructions :)
 
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Glad to hear that it cured! Most of the epoxy manufacturers make different grades to use under different conditions - slow, fast, medium, depending on temperature and how quickly you want it to set and cure. Just be careful. It is easy to get it to cure too quickly, especially if a mass of mixed epoxy is in a large concentrated area, like a deep cup. It can quickly gel, smoke, and be too hot to hold. One way to slow the catalyzing reaction if you sense it’s going to go off too quickly, is to mix the resin and hardener, then pour it into a wide, shallow pan as you apply it to your work.
 
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PS- also, don’t forget that most epoxy will degrade in time if exposed to UV light without a filtering agent over it. On boats that usually means varnish.
 
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I once had a rod on which the finish just refused to cure. I put it upstairs in my garage in summer heat and it still wouldn't cure. Advice from the rod building forum suggested that applying a second coat, more carefully prepared, would probably get the first application to cure. That might work for you, in case it still doesn't cure.
 
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