# Yellow hardener?

**URL:** <https://forum.clcboats.com/t/yellow-hardener/41956>\
**Category:** Builder's Forum\
**Created:** [March 20, 2014, 5:53pm UTC](https://forum.clcboats.com/t/yellow-hardener/41956 "2014-03-20T17:53:32Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Bret\_Warner](https://avatars.discourse-cdn.com/v4/letter/b/df788c/32.png) [@Bret\_Warner](https://forum.clcboats.com/u/Bret_Warner)\
**Post date:** [March 20, 2014, 5:53pm UTC](https://forum.clcboats.com/t/yellow-hardener/41956/1 "2014-03-20T17:53:32Z")

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I am on my second build now. I finished the first one in May 2013. I stored my leftover epoxy in my garage and in a shelf under my table. It does get over 100 during the summer and fall here. My garage stays a little cooler than outside but not much. When I went to use my epoxy/hardener for my new build the hardener was super yellow. Is this an issue? I am using MAS.&nbsp;

Thanks

Bret

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**Author:** ![James\_Allen](https://avatars.discourse-cdn.com/v4/letter/j/848f3c/32.png) [@James\_Allen](https://forum.clcboats.com/u/James_Allen)\
**Post date:** [March 20, 2014, 9:30pm UTC](https://forum.clcboats.com/t/yellow-hardener/41956/2 "2014-03-20T21:30:09Z")

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&nbsp; &nbsp;I have built 2 kayaks and am now finishing the build of a Northeaster Dory. &nbsp;I ran out of hardener just one or two little jobs Short of being done. &nbsp; I got out the dregs of my System Three epoxy left over from the 2nd kayak build (they were both Pygmy Boats kayaks). &nbsp;It was over 2 years old and the hardener was dark brown and the viscosity of sludge. &nbsp;I used it to make fillets, was a little worried about how good it was. &nbsp;The stuff hardened just fine. &nbsp;MAS and &nbsp;System Three both say that their epoxy will keep for years unmixed, although the hardener will darken. &nbsp; It should work just fine.&nbsp;

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**Author:** ![James\_Allen](https://avatars.discourse-cdn.com/v4/letter/j/848f3c/32.png) [@James\_Allen](https://forum.clcboats.com/u/James_Allen)\
**Post date:** [March 20, 2014, 9:32pm UTC](https://forum.clcboats.com/t/yellow-hardener/41956/3 "2014-03-20T21:32:07Z")

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&nbsp; &nbsp;To be clear, I used old resin and old hardener both &nbsp;from system three. &nbsp;Don't try to mix and match different brands of resin and hardener, that would probably not work!

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**Author:** ![Howard\_Spira](https://avatars.discourse-cdn.com/v4/letter/h/ec9cab/32.png) [@Howard\_Spira](https://forum.clcboats.com/u/Howard_Spira)\
**Post date:** [March 20, 2014, 10:58pm UTC](https://forum.clcboats.com/t/yellow-hardener/41956/4 "2014-03-20T22:58:34Z")

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i have old MAS (over 5 years)&nbsp;that i am still using.&nbsp; yes...hardener has yellowed...but no issues so far.

same situation....kept in garage.&nbsp; every season i end up using a bit for repairs.&nbsp; so i always do a small test batch each season to confirm it's still working before committing it to a repair or new piece.