basmntdweller

My Feedback: (9)

I mixed up some 30 minute last night to glass a wing center section. I mixed it in a one ounce cup and I mix by weight on scales. Anyway, I stirred it pretty good and started wetting out the cloth. In less than five minutes the cup was getting hot, real hot actually. In less than 10 minutes it had gone rock hard. Needless to say, I wasn't done wetting out the glass and anywhere near ready to scrape the excess off. I have a bit of a mess on the wing but that's nothing sandpaper can't fix. I thought this 30 minute epoxy was supposed to have 30 minutes of working time not less than 10 minutes! Anybody else experience this? My first thought was I had grabbed the wrong epoxy but I didn't. Any ideas what happened?
Thanks,,,basmntdweller

fredscz

My Feedback: (47)

If you weigh the separate bottles you may find one bottle is heavier than the other and you will have to compensate by using more of one than the other. I've not found that it has made as big a difference as you describe. If this is the first time you have used from these containers maybe they are labeled wrong from the maker.
Fred

tailskid

My Feedback: (34)

Temperature in your working area?

Jerry

basmntdweller

My Feedback: (9)

The weights of the bottles are very close, within a gram. That's after I have used maybe 1/4 of each. I have never had it kick off this fast before, it usually never even gets warm. The 6 minute epoxy from H9 dies get warm when it cure but I haven't had the 30 minute stuff get hot before.
Thanks,,,basmntdweller

Ghostrider FIN

I think you got too much or too deep epoxy in to mixing cup, i´ve got same kind of a problems with glass fiber laminating epoxy. If i put epoxy in to wide cup like a paper plate and only about 1/4inc. deep layer then i not have any kinda problems with it. I think this is caused by chemical reaction and it came faster if you but epoxy too deeply.

Sorry about my dumb English

bentgear

My guess would be that it is:

labeled wrong, or
epoxy in the containers was warm before mixing, or
stirred too much, creating heat in the mix, or
lost track of time, or
mixed in too big a batch for existing conditions, or
a little of all the above.

Epoxy can be a strange animal. Avoid anything that involves heat unless you need it to thin and flow quickly, but set up shortly thereafter. The worst I have ever done was when I mixed up a 5 gallon batch that had been setting in the sun. Thought it was going to catch on fire after about 30 seconds of mixing. Melted the 7 gallon pail I was mixing in and would not give the big mixer back.

Ed M.

Crash_N_Burn

My guess is that the product is mis marked and that you got 5/6 minute epoxy.

To be sure, try it again under the same conditions and see when it catalyzes.

I'm pretty casual with my epoxy mixing.......whoa, that's about right....and have never had any problems. Stir solidly for one minute, sit untouched for one minute. I treat 30 minute epoxy as 20 minute epoxy in the summer and 35 minute in the winter. Brand-for-brand, it's never let me down.

Try another test and let us know, OK?

basmntdweller

My Feedback: (9)

I mixed up another batch same size. It started getting warm at about 5-6 minutes, was real hot at about 9 minutes and basically solid at 12 minutes. I will try some of the 6 minute variety I have and see what it does. Oh, temps in my basement are usually high to mid sixties. This is the first I have used Hanger 9 brand as my LHS doesn't have my usual brand anymore. All the previous times I have used this epoxy, I have only mixed up small amounts and never checked on the cure times or paid any attention to how the excess was reacting. I'll post again after I try a batch of the 6 minute.
basmntdweller

Crash_N_Burn

I mixed up another batch same size. It started getting warm at about 5-6 minutes, was real hot at about 9 minutes and basically solid at 12 minutes. I will try some of the 6 minute variety I have and see what it does. Oh, temps in my basement are usually high to mid sixties. This is the first I have used Hanger 9 brand as my LHS doesn't have my usual brand anymore. All the previous times I have used this epoxy, I have only mixed up small amounts and never checked on the cure times or paid any attention to how the excess was reacting. I'll post again after I try a batch of the 6 minute.
---------------------------------------------
Nope, gotta be 6 minute epoxy at mid to high sixties ambient.

30 minute would be warm at 25-28 minutes, hot at 29-31 minutes and solid at 32-38 minutes.

I'll be danged, never heard of a mis marked epoxy package.

I think I'll try a batch first in the future before I commit.

Startling!

basmntdweller

My Feedback: (9)

I did a batch of six minute. Stirred for one minute, was warm to the touch three minutes from the start of stirring and solidified in seven minutes from the start of stirring. All these batches have been 10grams of each resin and hardener. I imagine the six minute, which normally wouldn't be mixed in this large of quantity is kicking faster because the heat generated by the catalyzation is causing it to cure out faster than normal. I would think that the 30 minute would be formulated for pot life of 30 minutes in a larger quantity like what I was working with. There weren't any pot size specs on either epoxies. I do have some 60 minute resin I got from Advanced Composites that specs a pot time of 60 minutes in a 150cc quantity.
Later,,,basmntdweller

Charlie P.

The only real difference in 6 mnute and 30 minute epoxy is the hardener/cataylst used. There is a great difference between working time and cure time. 30 minute epoxy means it is cured in 30 minutes. Working time will be lass than a third of that. I mix up epoxy for boatbuilding, and a pint of epoxy that would take four hours to cure if spread thin will have the endothermic reaction you noted if left sit for 15 minutes in the cup (melt the cup and actually froth, boil over and burn the wood mixing stick. That's over 450º!). The catalyst/hardener can link much faster if the batch is contained in a dense form. By spreading it out the surface area is greatly increased and the catalyst takes much longer to kick the batch over. Some fillers shorten work time, too.

Chilling the epoxy will lengthen the work time. NEVER try to adjust it by adding or reducing the amount of hardener. You'll eventually make a mess that never fully cures or cures poorly.

DMyer

My Feedback: (2)

Some good information on pot life in that previous post... IMHO... I only use quality resins... especially when fiberglassing. I use only Z-poxy resins for general building purposes. Z-Poxy quality and cure characteristics are the same in each batch versus all the no-name stuff sold under a zillion labels. For glassing I use only West Systems epoxy... 105 resin + 206 slow hardener. It has a much longer pot life and is very thin making it perfect for glassing either wing center sections(not thinned) or 1/2 oz surface glassing (thinned). Here is a link for more information:

http://www.westsystem.com/

West Systems can be purchased at any boat store.

I highly recommend glassing with either West Systems or Z-Poxy finishing resin versus any generic 30 minute. The 30 minute stuff is too thick to easily wet out the fabric remove the excess epoxy prior to it going off. Good luck on any future glassing!

Rodney

Ghostrider is correct, always mix epoxy in shallow containers, if they are deep, accelerated curring occurs.

basmntdweller

My Feedback: (9)

Z-poxy is what I normally use but the LHS has quit carrying it. After I cleaned up the mess I had on the wing I re-glassed it using the 60 minute resin I got from ACP. It works well, I just don't like mixing unequal amounts. The stuff from ACP is a 2:1 mix ratio by volume or 45:100 by weight. I used the 30 minute because I hadn't opened the ACP stuff and I had used Z-poxy 30 minute before for this.
basmntdweller

DMyer

My Feedback: (2)

The ACP Glue... is that the EASY-LAM, is real good stuff too. I use a triple beam to weight the west systems 5/1 mix.. they also have a pump set that pumps out the correct amount, but I often want smaller quantities mixed and just use the scale all the time by habit... very fast... very accurate. Glad you were able to get the mess cleaned up. I don't think there is a worse feeling "OH $$$$" than having epoxy go off prematurely during glassing!

basmntdweller

My Feedback: (9)

I was lucky. As soon as I saw it waas kicking off, I pulled the half applied glass off and tossed it and started scraping as much as I could. It's all done now, waiting on a filler coat of Easy-Lam. I couldn't remember the name of it earlier, just that it was 60 minute. It's kind of wierd that I could recall the mixing ratio by weight but not the name!
basmntdweller