Old lye: way to test if still active?

[Darbla]

I've got some lye I've had almost 2 years. Is there a way I can test whether it's still good for soaping or not?

[NewOrleansLady]

How does it react to warm water?

[CareBear]

if it's been stored in a well closed container and is not caked up then 99% sure it's fine.

if, on the other hand it's hardened into a solid chunk, is wet, or was stored 1-2# in the bottom of a 5 gallon bucket - not so confident.

[topofmurrayhill]

You can look at the Scientific Soapmaking book over at Caveman Chemistry. I think the current draft has instructions for performing a titration to determine the concentration of your lye -- but it's not a quick and easy test.

If the stuff is really questionable as CareBear describes, or if you need it to make saleable product, it could be better to just replace it. HDPE bottles are surprisingly porous so there could be some issues even if it's been tightly closed.

If it seems like it might be usable and you're only making soap for yourself, you could try making a batch with no lye discount (0% "superfat"). Using published SAP values and old lye, the chances of making a lye heavy batch are essentially zero.

Edited December 19, 2009 by topofmurrayhill

[Kitn]

I have done as topofmurrayhill described and the soap was fine . The lye was just old not caked or clumpy .