Uncured expoxy filler - advice needed

[ahun]

Too much hardener. Start over, it will never set.

[coopec43]

Originally Posted by Uncle Bob

Thank god we have an expert like yourself to provide guidance and clarification

I hope I learned something while constructing my yacht.

[Nicholson58]

Originally Posted by Vinny Barbarino

Hi all,

24 hours ago, I mixed West Systems epoxy and added filler, and filled in some old bolt holes on the deck. For the first time in two years, after many gallons of epoxy, I can say I'm not sure 100% that I got the ratio right.

Today:

The filler has not cured entirely. I can push my fingernail and make a mark. It's not sticky or tacky, it just hasn't fully hardened - it's too soft.

I'm in the Caribbean, and due to the temps here epoxy cures *very* fast. 24 hours is always enough time to harden and sand - but not this time.

My main question is - is it likely to fully harden, slower than normal, in the coming days, even if the ratio was wrong?

Or, will it never harden fully?

I'm trying to decide whether to remove everything (13 bolt holes worth), and redo, or just wait....

(another thing - the pot I used, the leftovers have a "flexibility" to them. Nothing is sticky/runny - just more flexible than normal.)

Cheers for any advice!

A lot of good advice here.

Are you at Power Boats? Ask Amos or Tony at Perfect Finish for their advice. They are really competent and may offer an OK shortcut. Tell them hello from Mark and Lynn on Roxy.

[arcticmonkey]

used epoxy for more than 20 years so I have had my share of successes and failures ... my advice is measure measure and measure again

[nmccubbin]

Agreed with the others saying that epoxy curing is not catalytic.
I would dig it our and try again.

One issue I have had with West and similar epoxies that the two components must be VERY well mixed to cure to full strength. MUCH more than with polyesters

When I mix an ounce manually I stir the cup for a full 3 minutes.
I did some tests with minimal mixing, and glue strength was poor.

[Dave9111]

Its very easy to get the ratio way out of wack with a 5:1 mix.
A 2:1 mix is much more forgiving.

I really don't know why they still make a 5:1 mix.
That should be made obsolete.

[Turtle Blues]

Yes, I stand chastised and corrected. I should not have used the word catalyst.

[I14]

I'm a retired polymer chemist so have learnt most of these problems the hard way! We formulate, as others have said, epoxies to react together exactly in a correct ratio called a 'mole ratio'. If the ratio is wrong, either too much epoxy A or too much amine B then the part that's in excess will act to plasticise the mix ie. it will stay soft to a degree. An excess of epoxy A is not quite so bad as it is slightly volatile so over a period of time the mix will harden some more. The epoxy A on its own is effectively stable for a very long time on storage but the amine B is not so watch out that your part B isn't too old or has been left exposed to the air too much, plastic bottles are bad for this as over time air and humidity can get through the plastic. Either way best to dig it out and replace

[Vinny Barbarino]

UPDATE:

I drilled/sanded all the uncured epoxy out, and did the job over.

I'm pretty sure the problem was old epoxy, not the ratio. I've been re-using West Systems tins - as I can get substantially cheaper refills here (those one gallon tins must have seen through 10 gallons). With the failed batch, it was the very bottom of the tin, the oldest stuff, that came out. It took the purchase of a new set of tins and pumps to see and remember just how clear epoxy should be.

Lessons learned, thanks to all.

[capt jgw]

I've had that happen too. There definitely is a shelf life, I'm not sure what it is but I've exceeded it too. I think WEST says one year, but that's more about getting you to buy more than the actual life.

[coopec43]

Originally Posted by capt jgw

I've had that happen too. There definitely is a shelf life, I'm not sure what it is but I've exceeded it too. I think WEST says one year, but that's more about getting you to buy more than the actual life.

I wouldn't take Wests word for it. I have used 3/4 year old resin with excellent results.

Epoxy resin and hardener formulations have a long shelf life compared to many polymers. The minimum shelf life for the standard INF and LAM products is 3 years for resins and 2 years for hardeners (with the exception of LAM-251-HT). The minimum shelf life for LAM-251-HT and all ADV resins and hardeners is 18 months.

https://www.prosetepoxy.com/home/shelf-life-storage/

[Vinny Barbarino]

For the data:


This was approximately two years worth of refilling the same tin, in the Caribbean (hot!). I believe it was the hardener - slightly discoloured.

[coopec43]

Originally Posted by Vinny Barbarino

For the data:


This was approximately two years worth of refilling the same tin, in the Caribbean (hot!). I believe it was the hardener - slightly discoloured.

You could be right.

"If the epoxy hardener is dark yellow or orange in color, the product may have passed its expiration date, stored in extreme temperatures or exposed to UV rays. The epoxy resin should still cure properly, but a test batch is recommended to ensure that the finished, cured results are not discolored to dissatisfaction".

https://promiseepoxy.com/blogs/promi...-in-the-bottle