epoxy didn't cure

[chergui]

I mixed some epoxy yesterday to glue up my transom. Went down today, about 20 hours later and found that it was gummy and not totally hard. I've never had a problem mixing epoxy before. I used the same stuff a couple of weeks ago and it was fine. I was mixing a small amount and may have put in slightly more resin than called for. But the amount was so little I would have had to ad so little hardener I didn't think it would matter. I'm sure I've been off by this much before and its never made a difference. I made about 30 ml or just over an ounce. The resin may have creeped up higher on me in my measuring cup once it settled. How annoying. Guess I get to cut up my transom for the second time. I suppose that's what I should do. Is there any chance the epoxy will harden enough in the joint to be good enough?

[Dolly Varden]

id apply some heat and see what happens. do you have the leftovers still in the cup? take them indoors let it set up a week or so and if you have a durometer, take a reading and see what it says. that compared to what the reading of the finished product should be after 168 hours at that temp should tell you how close to full strength your mixture actually is

[JimD]

I agree. Put some heat on it and see if its a temperature issue. A single lightbulb up close to the surface will harden it up if the mix was ok. If heat doesn't do the trick then almost certainly you were too far off with the ratio. Nothing to do in that case except clean the gummy stuff off thoroughly and try again.

[Peter Heiberg]

I'm not an expert on epoxy but like most people have used it for years. The only failure I have ever experienced was from not allowing enough time for it to cross link after mixing. Perhaps that's another way of saying, insufficient mixing.

[John Turpin]

I wouldn't trust that epoxy. I'd redo that work ASAP.

My first thought was that one of your pumps might have been partially plugged and you got a different ratio than you thought. But, it sounds like you were looking closely at your measuring cup. I just remember that, in his book, Sam Devlin said that whenever he came in the next day to find uncured epoxy, he immediately cleaned/replaced his pumps to solve the problem.

[Thorne]

Sounds like everyone else has much quicker-curing epoxy than I do -- none of mine cures quicker than 3-5 days. But once cured, it stays rock-hard.

I'd say wait and see. Do some serious testing, but maybe it just needs time to cure?

[capt jake]

It may also be a factor of not enough heat. It will cure (assuming it is mixed correctly) eventually; but giving it the proper amount of heat will help it out.

Just a thought.

[chergui]

I'm in a shop though and its quite warm in there, 80 degrees almost all the time. I'm afraid I won't be able to separate the joints without cutting though but I'll try. Also, I'm using a bottle not a pump. I always leave the extra in the mixing container so I can check it the next day. I'm afraid to say I doubt very much that it will cure now.

I saw this happen once before, except the guy in the boat yard mixed it. I checked the container the next day and noticed it was gummy. I made them take the through-hull fitting off so I could check the end grain that I had epoxied. Sure enough it was gummy, just like this.

Is there anything that will help loosen the epoxy so I don't have to cut the boards? Heat gun?

[ 02-26-2006, 07:10 PM: Message edited by: chergui ]

[chergui]

ignore

[ 02-26-2006, 07:11 PM: Message edited by: chergui ]

[chergui]

Oops please ignore this.

[Thorne]

Well, it it is not cured, plain old cheap vinegar will clean it up very nicely. Be sure to wipe all of it away before applying any other epoxy products.

[Dolly Varden]

what exactly did you glue up?

[Bob Perkins]

Epoxy will cure properly if mixed in proper proportions plus/minus 10% usually.

Since you are in Vancouver, I'd guess it is just too cold up there? Like they said, bring the mixing cup indoors and see how it does. If it hardens - yours will too..eventually..

Good luck,
Bob

[chergui]

Originally posted by Dolly Varden:
what exactly did you glue up?I was glueing up my H. mahog transom. It's made of 3 boards about 36" long and 7" wide each. I don't want to joint the edges again, it took me a long time to get it perfect! On the other hand I'm getting better at jointing smile.gif

[JimConlin]

If the affected part is transom glue-up, take it to the table saw and lose a few kerfs' width. The risk of its coming apart later is intolerable.

For measuring epoxy, i use the pumps up to a pint or so, and a cooking scale for greater quantities. Measuring cups are inherently inaccurate, especially for small amounts.

[Don Kurylko]

As likely as not you mixed in too much hardener. A little extra resin is okay, to an extent, but too much hardener and the mix will never cure properly. It happens sometimes. Try wetting out the area with methyl hydrate. It might dissolve the goop. If not, apply high heat and “melt” the epoxy. It will become runny and you should be able to pull the joint apart. Epoxy "melts" at about 150 degrees F.

[Barry]

Just a thought, but has the resin crystallized?
Check inside the resin container for flakes, crystals or cloudiness. This will cause the epoxy not to cure properly. If so,place the container in a warm water bath(simmer) for about an hour and it should reconstitute. If not probably a bad mix as you stated.

[epoxyboy]

I have got into the habit of "burping" my pumps after a similar problem with a small "one pump" batch - the hardener pump in particular seems to drain out after a few days. I just push slowly until a drop of hardener comes out so I know all the air has gone, release the pump so it fills properly then pump out the required amount.

Pete

[chergui]

I checked it again yesterday and was surprised to see that it had finally cured! I guess I did put too much resin in and that may have slowed down the process. I've never seen it take that long before though.

[capt jake]

I checked it again yesterday and was surprised to see that it had finally cured! I guess I did put too much resin in and that may have slowed down the process. I've never seen it take that long before though. Must be an effect of Spring and the warmer weather. ;) LOL

[gert]

Seeing as how you are in Vancouver you should be using ColdCure or G2 from Fibertec on Boundry (who wants to leave the heat maxed overnight in a shop anyway?) very forgiving, slightly tacky at 24hrs is normal; I always clamp for 48.

Ignore the problem cause it aint one.

Whatcha building?

[ 03-03-2006, 05:41 PM: Message edited by: gert ]

[JimConlin]

Though the epoxy has hardened somewhat, i'd still worry about whether it has the strength you want if you're going to build a boat around that panel.

[chergui]

Hey gert. I'm building Paul Gartsides 7' clinker pram. I've got the molds up on the strongback and I'm getting ready to attach the transoms to it. I'll soon be working on the keel and figuring out the bevel on the transoms.

[ken.bryant]

Another local Gartside builder! Sending you an email...

[Rob Stokes, N. Vancouver]

Tag me as another who's embarking on the Gartside pram trail. I've not started yet, but am well into the study phase and am busy trying to secure a decent log that can be milled into planking stock.

Rob

[cs]

What brand of epoxy are you using? I used a brand one time that didn't kick good. I'll never use that brand again and stick with RAKA.

Chad