MAS hardener is yellow :(

I recieved a pint of hardener by MAS.  The liquid is very yellow to brown like.  I noticed the foil seal was broken.  I have heard this means that water or air got into the hardener.  I was told it is still fine.  I can't believe that.  I mixed it with the clear resin and it still had a yellow hue to it.  I would be afraid to put it on my kayak especially I am on my last step to finishing my project.  I'm not going to make a mistake at my last step and then ruin it now.  Or will it?  I am planning to fill the weave of the outside seem tape.  I feel it should be clear as day for this step.  Yellow would ruin it.  Should take it back?

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RE: MAS hardener is yellow :(

   My understanding is the discoloration is typical over time whether it is opened or not.  I have a bottle from a previous boat build that turned brown.  It is not supposed to effect the quality (MAS has an FAQ on this).  What you can do is mix up a small amount and put it on some scrap wood and see if it hardens.  If it hardens, then you should be fine.  If it stays tacky, then you should get rid of it.  The color will be yellow/dark so you wouldn't want to use it on any bright areas.

That being said, if you bought it new and it is brown, then I would see if you can return it.


RE: MAS hardener is yellow :(

All epoxy hardeners darken with age.  However, I have found it makes VERY LITTLE  or even no difference in the appearance of epoxy clear-coatings.  Try a test batch to see, but unless the epoxy has been frozen I'm sure it's fine.

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