Where the
world gathers for metal finishing
Q&As since 1989


-----

Expired glass fibre resin?

Has glass fibre resin an expire date? Some years ago, I purchased some glass fibre resin and did not use (work on) them. They are kept in airtight tins but are now solidifying. I was told that they will lose their strength in that state and must be discarded. Can I use some kind of solvents (like paint thinners) to dissolve the resin again?

Lawrance Chee
Education - Singapore
2003

---

2003

Hi Lawrance (should that not read Lawrence?)

I think that you have lucked out.

There is a time when the standard store bought Polyester or Vinlyester resins will lose potency. What that time frame is, I don't know. Why? Because the store bought cans are already 'promoted' ... the name? I forget. I think that is called cobalt napthenate.

It would be far too dangerous for individuals to promote the resin on the off-chance that they mixed the catalyst {methylethyl ketone benzoyl peroxide (I think)} as that causes an explosive reaction with the promoter.

The professionals DON'T buy/acquire already 'promoted' resins. Mind you, we're talking about 45 gal. drums. In order to keep their resins for a long time, they add the promoter AND the catalyst separately into the resin.

Having thoroughly bored you, may I suggest you acquire some more resin. Sorry to be negative.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

---

Thanks,
Freeman, for your reply. I learnt quite a bit searching thru' the names of the chemicals you have mentioned. The fibre glass resin which I have purchased are not the premixed type i.e., one needs to add the catalyst (hardener) prior to usage.

The resin which I have are still soft and that was why I had thought I could add some solvents to liquefy it. If you still think the resin is expired after remaining in the tins for years, I'll have to discard them.

Name - it was spelt this way for some auspicious reasons : to change life's destiny. When one is really down, you'll want to close all the loops. I was told there a re too many 'E's in my name.

Don't laugh!

All the best.

Lawrance CHEE
- Singapore
2003

---

2003

Hi again Lawrance,

My apologies! I did spell your name wrong !

Just one point ... one ALWAYS needs to add catalyst to cure the resin ... hence the store variety is always like that and comes already prepromoted.

We had to store the promoter and the catalyst separately due to the fire/explosion hazard risk. What you could perhaps do with your resin is to try and add some acetone [on eBay or Amazon] to make it more manageable. I won't say that this will work, but give it a try. And if it works, PLEASE let me know, OK?

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

---

Hi Freeman,

Thanks. I haven't the free time to try your last suggestion due to heavy work load. I shall try it out and let you know whether there is any success, soon.

Lawrance CHEE
- Singapore
2003