Crystalization of Epoxy

Crystallization of epoxy

Today I set the metal 5 gallon container of epoxy on my electric coil of my smoker.

If you looked into the can's hole what you saw was a white solid block.

In two and one half hours the solid block of epoxy was a clear liquid. You could see the bottom of the can very clearly. It worked slick. I had surrounded the smoker unit with alum plates to form a "tent'" to hold in the heat. I didn't monitor the actual tempature but the can's top handle was too hot to hold after I removed the tent and looked into the hole.

It took a couple of brew pops to cool off my right hand's fingers.
Thanks for your assistance.

phil w.

 

After heating, give it a good shake (gloved hands, don't burn yourself) to also dissolve the crystals which can be on the top

 

just a quick comment on Herman above. With some epoxies the crystals form on the top, with other epoxies they from on the bottom. In some epoxies you see crystals, with others it just turns milky (more common),

note that often you don't quite melt all the crystals and the remaining crystals act as 'seeds' and the epoxy may crystallize sooner rather than later. Sounds like the above folks got it well heated/melted!

Some epoxies crystallize more than others and some production batches seem to do it while other do not. Generally the more 'pure' the epoxy the more likely it is to crystallize but this is a very very rough generalization.

paul
progressive epoxy polymers inc

 

Oh yes, and things sometimes get really spooky. I have one resin which sometimes does, sometimes does not crystallise. Then when decanted into transparent containers, half of them crystallise, half not. Until the next morning, when the crystalised stuff is good again, but the other half is crystalised. Anyhow, my customer uses it at 180 degrees C (yes, very hot) and I never heard him complain...

 

Went by a boat builder the other day and noticed that he had one of the drums half wrapped. I ask him what that was all about. He stores them with an electric blanket wrap around the bottom of barrel. He says it keeps it fresh by circulating the fluid. Never seen that before. Never done that. I just give them a couple of hours of sunlight early in morning to get them a little warn before I use them.

 

In Florida? Thought thers's warm enough but obviously not..

 

When I am doing a floor, I warm epoxy a little to make it more liquidy and just pour it on and let it self level.

 

Question; Would there be a benefit to warm the epoxy before you use it to wet f'glass cloth, as on a small boat? Would it facillitate the cloth wetting more thorough or faster? If so what would be a good temp to take it to?
phil w

 

Phil,

I don't think anyone will be able to answer that question without knowing exactly what kind of epoxy it is. Do you have any manufacturer data?


Allan

 

Epoxy

Allen,
I've used West System's 105/207 in the past on my Canoe. I have recently come into DOW's D.E.R. 331 Epoxy. I haven't been able to use it yet, the hardener I received with it is their D. E. H. 24, however it has exceeded the shelf life. I am trying to find a way to obtain new hardener. Their Tech Data lists Marine Applications so I hope to use it. I have 10 Gallons & hate not to be able to use it for building a Drift Boat which will require a few gallons.
Thanks for any assistance,

phil w.

 

Better not.. Not that epoxy wouldn't stand it but if you pour warmer epoxy to colder surface it may couse of gassing if there's porous surface. Better other way round, ie warm surface and colder epoxy and room temp!
BR Teddy

 

Warm epoxy will wetout fabric faster, but it'll also kick faster, so it's a trade off. Unless working in a cool environment, most laminating resins will wetout fabrics well enough at room temperature, while providing enough working time to permit spreading it around.

I have little to no difficulty with crystallizing in Florida, nor do I find the need to "keep it fresh" which I think is silly. On the rare occasion it's been cold enough to cause an issue, some warm water or warm box has solved the problem.

How far out of date is the hardener? I've used hardener that was several years old after opening and it worked fine, though wasn't tested. If the container hasn't been opened, you're likely just fine using it as is, out of date or not.

 

PAR,

Thanks for the info. The date on the label and Lot No. of the batch isn't legible. Dow's Tech Info says the Hardener is good for 24 months. My guess is that its much longer than that. A friend had plans to build a boat but moved out of town about four-five years ago and just last year sold his house and had to clean it out real fast, that's how I came to getting it. Price was right, ZIPO. I guess I owe him a few brews, next time I see him.

I tried last fall to mix some and let it harden in a small plastic cup, I pitched it after a couple days it was stickey not hard like I am used to. The Tech Sheet's from Dow say to mix 13 parts by weight of hardener to 100 parts by weight resin. The ratio is significantly different from most other brands ratios so I mixed it 2:1, like West's 105/206. My logic was, I received two 5 gallon cans of resin and one of hardener, duh. Maybe I should give it another try, eh.
phil w.

 

You have to be pretty close on the mix ratio, or you can expect curing issues. In your example, you took an 8:1 ratio epoxy and tried a 2:1, with obvious results. Mix at 8:1 and it'll likely work just fine, assuming it's not contaminated or been stored in a particularity harsh environment. These higher ratio mixtures are much more sensitive to ratio deviations, than the the lower 2 and 3:1 formulations (understandably), so have a go at a new batch.

 

So if your doctor tells you to take a pill a day, and you receive a bag full, you swallow them by the dozen?

If Dow says 100:13, then the least you can do is try that mixing ratio. It might even work.
See the datasheet for DEH24, they were nice enough to include the mixing ratio with DER 331 on the datasheet. Potlife at 25 degrees is 25 minutes or so. Pretty fast if you are doing large pieces.
http://msdssearch.dow.com/Published...poxy/pdfs/noreg/296-01496.pdf&fromPage=GetDoc

Besides that, West 105/206 is 100:20. See their datasheet.
http://www.westsystem.com/ss/assets/Product-Data-PDFs/105206-Technical-Data.pdf

Always keep as close as possible to the mixing ratios. This is epoxy, not magic goo.