How important is the temperature of lye when making soap?

by Sue Landt
(Hartford, USA)

I have some old potassium hydroxide and want to make liquid soap(turned hard over time) When I mixed it with water, it only got to 74 degrees. Can I continue or won't it turn out?

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How important is the temperature of lye when making soap?

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Dec 09, 2009

Making Soft Soaps and Correct Temperatures
by: Countryfarm Lifestyles

Hi Sue

I take it that you are referring to the fact that your potassium hydroxide has hardened over time, not your soap. If you use potassium hydroxide it is usually for soft soaps, which are your liquid soaps and won't harden over time.

It sounds as if your potassium hydroxide is past its used by date. If you have kept this chemical too long, what happens is that it loses its potency and therefore it won't reach the temperature that you are hoping for.

The ideal temperature that you should be aiming for 71°C or 160°F.

You say that you can only get the potassium hydroxide to 74°. If you are talking Celsius, that is fine, however, if you are talking Fahrenheit then you have a problem.

The water & potassium hydroxide temperature must be approximately the same as the oil temperature before you combine the two phases.