Mineral Oil Saponification?

boyago · Dec 3, 2013

I was under the impression that mineral oil would not saponify and that is why it's a good mold lube. My most recent batch was in a vert gutter mold and heavily greased with Mineral Oil. It looks like the mineral oil sapped. Or does this look like something else? Now that I have thought about for two seconds I would think that the most MO would be on the base and it does not have this white stuff on it. It is mostly in the middle which is where most of the heat would have been... Any ideas?

soap_rat · Dec 3, 2013

Since the mold was vertical it does seem less likely that it was the mineral oil. However, I did find that mineral oil discolored/changed the opacity of my soap in spots, when I left a good residue in the mold for help in unmolding. I didn't have brown soap turn white, though. Is there something else you used for grease prior to this, that may have stuck there and affected it? Or even the previous soap batch?

boyago · Dec 3, 2013

That was the first batch in that mold. I scraped some off and it seems identical to the texture of the soap. The mineral oil of course does not have a full list of ingredients since but does say that it contains Vitamin E as a preservative. I put out a cup with some lye to see what happens.

shunt2011 · Dec 3, 2013

Maybe a reaction between the MO, the mold and the soap batter. It also looks like it may have also gotten pretty hot....just a guess as I've not used that kind of mold before. I have used MO to lube up my HDPE slab and have not gotten that kind of reaction, though now I just spray it with non-stick cooking spray and it works like a charm. Sorry I can't offer more help.

boyago · Dec 3, 2013

Well nothing happened with the NaOH + MO. This one did produce heat but as I checked on it it was never much more than warm to touch. I have had other soaps go way hotter for longer but it's possible since they were not dark soaps that I didn't see the reaction.

Side Note: The MO + Lye retained the viscousity of the MO. I think I just made the gel style drain cleaner.

seven · Dec 3, 2013

shunt2011 said:
Maybe a reaction between the MO, the mold and the soap batter. It also looks like it may have also gotten pretty hot....just a guess as I've not used that kind of mold before. I have used MO to lube up my HDPE slab and have not gotten that kind of reaction, though now I just spray it with non-stick cooking spray and it works like a charm. Sorry I can't offer more help.

so non-stick cooking spray is okay to use? i thought i read somewhere not to use it because then the lye monster will want to eat it? i have a canola one, would that be okay to use?

also, i read somewhere (cant remember where though), that some people used dimethicone to lube up plastic molds and it worked like a charm (re: unmolding).

boyago · Dec 4, 2013

shunt2011 said:
Maybe a reaction between the MO, the mold and the soap batter. It also looks like it may have also gotten pretty hot....just a guess as I've not used that kind of mold before. I have used MO to lube up my HDPE slab and have not gotten that kind of reaction, though now I just spray it with non-stick cooking spray and it works like a charm. Sorry I can't offer more help.

Can the heat alone do that? It looks to have full gelled.

new12soap · Dec 4, 2013

you said your mold was a piece of gutter material, was it by any chance aluminum? I really hope not (never never NEVER use aluminum with lye), but if it was that's what happened.

boyago · Dec 5, 2013

This was actually steel which look like they are sealed with a powder coat. Alloy steel will also react with NaOH as well. I have used aluminum in the past though and when the batter hits exposed aluminum it tends to make a gross looking rusty gel not the clean white soapy coating that happened here.

Please note I am not trying to make the light of the reaction between Lye and aluminum. It's bad.

judymoody · Dec 5, 2013

I wonder if the raw soap didn't play nicely with the powder coating? Even with the mineral oil, the coverage might have been less even after you poured your soap.

boyago · Dec 5, 2013

judymoody said:
I wonder if the raw soap didn't play nicely with the powder coating? Even with the mineral oil, the coverage might have been less even after you poured your soap.

Good thing I thought ahead and didn't wash the mold (wink wink absolutely part of the plan). Ding Ding your the winner! The finish looks matte in the same spots that the soap was affected. It's way past time I broke down and bought some real molds.

Mystery solved. Two Sherlocks for Judy!

Now for the mystery of who wants soap contaminated with probably toxic Chinese paint.

Nellie45 · Dec 5, 2013

Well i Really appreciate this post. It’s hard to sort the good from the bad sometimes, but I think you’ve nailed it!

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