Epoxy is not curing - a sticky mess

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len sandok
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Epoxy is not curing - a sticky mess

Post by len sandok »

I live in Minnesota and have been waiting all winter for it to be warm enough for me to encapsulate my little Tubby Tug parts. I thought that day was yesterday. I mixed the epoxy and did all the parts I had ready. Most of the parts are fine, but some are not curing and they are a sticky mess. I have two suspects as to the cause. It was the last batch of epoxy I mixed yesterday and I might have mistaken the portion of hardener to epoxy. It could also be that the temperature dropped below freezing last night.

I plan to wait a day or so to see if it cures by itself. If it is still a mess, what do you all suggest? Should I “dry” the parts with a hair dryer? How do I get that stuff off of those parts? Suggestions appreciated.

khundley
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Re: Epoxy is not curing - a sticky mess

Post by khundley »

If you have any goose neck lamps you could place them near the sticky spots. The directed light, especially close...creates a surprising amount of heat. You don't want to get the areas hot, but you do want them quite warm. Keep the builb 12-16" from the hot spots. That might get the hardner to kick in.
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vupilot
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Re: Epoxy is not curing - a sticky mess

Post by vupilot »

I hate when that happens. Give it a day or two to see if it wont cure. What I found works on flat surfaces if youre careful not to damage the wood is that you might save some sandpaper buy scraping as much off as you can first. I use my widest old chisel to scrape the majority of it off then sand the rest, it will gum up your sandpaper in no time.

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DaveLott
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Re: Epoxy is not curing - a sticky mess

Post by DaveLott »

I had that happen to me on a whole side of my boat in February. I did not know if I mixed it up wrong or if it was the temps so I chose to remove it and started over. I bought a 100 pak of 80 grit paper for me RO and went at it . A disc only last a few minutes but it does take it off

Otherwise, if you are sure you mixed it properly you just need to wait it out with some heat.
Dave

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thudpucker
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Re: Epoxy is not curing - a sticky mess

Post by thudpucker »

I read these posts because I'm an abject failure at F/Glass.
All I've ever wound up with is a Sticky mess!

Sometimes it worked out when I put a Reddy-Heater in the building for a day or so.

But...I really never have seen an explanation by the F/Glass people on what to do when it happens, and what the heck you did to cause it.

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Bob Perkins
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Re: Epoxy is not curing - a sticky mess

Post by Bob Perkins »

There are only two things (IMHO) that will cause the epoxy not to cure.

1. Too cold.
2. Improper mix


#1 - Easy to fix - just warm things up as everyone suggests and it will cure. no worries here.

#2 - Most common way to mess up epoxy unfortunately. My suggestions to avoid the big sticky mess:
- STOP using the crappy pumps that come with epoxy - they always get gummed up and ruin your mix.
- Buy a digital kitchen scale and weigh your batches. This is more accurate than little measuring cups or pumps.
I used System 3 which is a 2:1 ratio resin to catalyst - very easy to weigh on the scale.
If you use West System - it is 5:1 - make up a chart using Excel or something to get the right weight combinations.
- When you are mixing epoxy - look at a clock with a second hand. On large batches - I mix 60 seconds - on little batches - 30 seconds.
You will be surprised how long 30 seconds is - you can't over mix epoxy - you can only under mix it.

Epoxy must be mixed in the proper ratio +-10% of each component. Otherwise there will be left over molecules that do not combine, leaving your sticky mess. Same if it is not mixed properly. Mixing gets all of the epoxy molecules together.

I'm mixed up many gallons of epoxy now and have never had a batch not work properly.
Trust me when I tell you - just weigh your mix - then mix for 30-60 seconds. you will not have issues.
good luck
Bob
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Bill Edmundson
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Re: Epoxy is not curing - a sticky mess

Post by Bill Edmundson »

I use the pumps and have never had a problem. I think some people have a had a problem with 1:1 ratio resins:hardener brands. They mixed resin with resin.

Assuming that you did not mix resin:resin, it will go off when it warms up.

Bill
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thudpucker
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Re: Epoxy is not curing - a sticky mess

Post by thudpucker »

Well....after all these years of Sticky, Bob finally exposed the problem.
There's a intelligence test involved! :x
It aint just following the instructions, it's knowing how to do all that other stuff like timing the mix et al.

I figgerd out warm!
I posted late last year on making a Temporary floor heater. A cost reduced model.
About $150 to start and $30/Month and you have even temperature all winter long and pretty cheap too.

The mixing ratio, whether it be pump or cup and digital scale, still requires patience and experience.

On the subject of being the correct temp; Can the temp be too high?
I'm not too far from Bill and we get temps up into the 90's with Humidity.
Is that too much?

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vupilot
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Re: Epoxy is not curing - a sticky mess

Post by vupilot »

The higher the temp, the less working time you have (pot life) Also the bigger the batch the less time you have. Gluing and encapsulating parts wasnt a problem in 95 degrees for me but I dont think I would want to try fiberglassing an entire boat in 95-100 degree temps unless I had a lot of experienced helping hands so we could do it fast

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leakcheck
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Re: Epoxy is not curing - a sticky mess

Post by leakcheck »

If you must remove it: furniture scrapers and vinegar !! Or any combination of the two!~

Steve

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thudpucker
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Re: Epoxy is not curing - a sticky mess

Post by thudpucker »

Remove what Steve? Excess F/glass? Meaning the Mix got too Hot and you didn't get it all in place before it set?
Or are you talking about cleaning the tools? :|

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Bob Perkins
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Re: Epoxy is not curing - a sticky mess

Post by Bob Perkins »

Yes - White Vinegar does a great job on cleanup - good reminder ;)

I had a little factory training on epoxy - a great way to describe it is that it behaves the opposite of paint.

for instance - if you leave cup of paint open in the air.. it will never *dry* so to speak... however - spread thin on something... dries quickly. That is because it is air dried (think latex)

Mix up a cup of epoxy and it will generate so much heat it will boil over... Spread it thin and you have a lot more working time... When I was making large batches - I poured it into a pie plate to keep it thin - so that it could not generate as much heat.

HTH
Bob
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thudpucker
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Re: Epoxy is not curing - a sticky mess

Post by thudpucker »

:lol: Your talking about Sour Dough Bread right? :P
A pot fulla that stuff will rise up over the pot. You can feed the masses with that stuff, spread thin or thick.

Thanks for the very accurate and easily understandable Explanation. :D

len sandok
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Re: Epoxy is not curing - a sticky mess

Post by len sandok »

Len here again, I am the originator of this thread. I think the mess is drying but it is taking way too long. However, I have a basic question. The ratio of epoxy to hardener is 5 to 1, but I assumed (that's probably the problem right there) that the ratio was in VOLUME not WEIGHT. I built a squit a few years ago and head no problem mixing by volume. I was using West products last time. This time I am using an AD-Tech product.

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Bob Perkins
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Re: Epoxy is not curing - a sticky mess

Post by Bob Perkins »

You are correct. It is by volume and not weight. The epoxies I have used - the resin and hardener weighed the same by volume. So it all worked out.
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Bob Perkins

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