Epoxy not gone off...

[nigelmercier]

... temperature is not particularly significant with epoxy...

Sorry, but I disagree. The West Epoxy has clear instructions for the minimum temperatures, the slow hardener being higher. The man at West said that if mixed below these temperatures, it will cure very slowly, if at all. To make it then cure the temperature has to be increased dramatically to above 30° C, or 40° C if possible.

 

[Avocet]

My best guess would be a duff batch of hardener. I find the hardener is much more "finicky" about storage conditions than the resin. If the top on the can isn't a perfect seal, moisture gets in and it goes deep ruby red and stinks of ammoina.

I'm also not sure if all epoxies are the same, but on the SP stuff that I'm familiar with, the hardener has a great affinity for moisture - prefering to react with that rather than the resin. Significant humidity seems to lead to incomplete cure.

Is it possible that there was a fair bit of moisture in the thing you were sticking it to?

 

[Poignard]

Anyway, next question is: How the hell do you clean off the sticky uncured resin?

 

[BERT T]

Sorry, but I disagree. The West Epoxy has clear instructions for the minimum temperatures, the slow hardener being higher. The man at West said that if mixed below these temperatures, it will cure very slowly, if at all. To make it then cure the temperature has to be increased dramatically to above 30° C, or 40° C if possible.

Temperature is critical, especially on the slower curing epoxys. I use an epoxy similar to that used in the construction of wind turbine blades which has a very low shrinkage factor and temperature has an effect an the cure.

 

[Avocet]

Anyway, next question is: How the hell do you clean off the sticky uncured resin?

Depending on how far cured it is, I think meths or acetone are probably favourite?

 

[Iain C]

Depending on how far cured it is, I think meths or acetone are probably favourite?

Oi, have you been in my boat's drinks cabinet again?

 

[prv]

Anyway, next question is: How the hell do you clean off the sticky uncured resin?

I've heard of people using vinegar to clean tools. Worth a try?

Pete

 

[Poignard]

I've heard of people using vinegar to clean tools. Worth a try?

Pete

Certainly worth a try. All sorts of uses for vinegar

http://www.vinegartips.com/Scripts/

 

[VicS]

I've heard of people using vinegar to clean tools. Worth a try?

Pete

I'm doubtful if a dilute aqueous solution of ethanoic acid will be effective, but you can but try.

I'd have more confidence in an organic solvent such as propanone or ethanol

 

[prv]

I'm doubtful if a dilute aqueous solution of ethanoic acid will be effective, but you can but try.

I never have tried, but it seems to be moderately popular among American dinghy builders.

Personally I just treat all epoxy-handling tools as disposable. Cheap B&Q brushes, scrap offcuts of wood, and plastic cups.

Pete

 

[Iain C]

Grrrrrr...just typed a long update and somehow lost it in cyberspace.

I found a slimy, watery mixing pot. It looks like either the pot was contaminated with a liquid (water or acetone) or more likely something has pooled on the top of the epoxy can and got poured into the mix. Such are the hazards of working in a slightly messy, poorly lit man-shed!

Subsequent mixes seem OK...I ripped all the suspect stuff off and re-did it.

Thanks for the suggestions anyway!