Don't make epsom salt bars

[Kosmerta]

I'm making this thread for anyone who wonders what I just did and comes here to search for it, no epsom salt cannot be used to make epsom salt soap bars XD

I'm making soap and currently out of sodium lactate. I've heard salt in lye water can help soap harden faster, but I also am out of table salt. Puzzeled I look around my soaping room and spy a bag of magnesium sulfate epsom salt.

Ah-ha! I thought to myself, that should work.... but then, luckily, I second guessed my self. I know magnesium is not a strong electrolyte, and would likely react with the NaOH. I pulled out my chemistry notes from last year and sure enough, MgOH is on my list of insoluble compounds- meaning the epsom salt would form an insoluble powder at the bottom of my lye solution and create a huge lye discount if used. Additionally, magnesium is one of the ions responsible for soap scum so if you are here because you searched "can epsom salt be used in soap?" Your answer is no.

Edit: typo

 

[lenarenee]

Aha! Well, simply because of reading older posts on SMF, I knew epsom salt wouldn't work, but didn't know why. And now, I almost know why! (I wasn't in your chemistry class)

 

[DeeAnna]

I agree that epsom salt shouldn't be used in soap for the reasons you share. But epsom salt is magnesium sulfate, not magnesium oxide.

Magnesium oxide when mixed with water forms magnesium hydroxide, the active ingredient that gives Milk of Magnesia its laxative and antacid effect.

 

[Kosmerta]

I agree that epsom salt shouldn't be used in soap for the reasons you share. But epsom salt is magnesium sulfate, not magnesium oxide.

Magnesium oxide when mixed with water forms magnesium hydroxide, the active ingredient that gives Milk of Magnesia its laxative and antacid effect.

Thanks, my bad. I fixed the typo