Dish soap

[DeeAnna]

When I talk about soap scum, I'm talking about insoluble chemicals that are created when hard water minerals (calcium and magnesium being the main ones) react with your solid bar of sodium soap or your liquid potassium soap. The insoluble chemicals are also soaps -- calcium soap and magnesium soap -- but these particular soaps are not soluble in water at all, so the particles of scum want to stick to your skin or hair and not rinse off cleanly.

Another issue to consider is the solubility of various soaps in water. Palmitic and stearic soaps are not as soluble in water as other soaps such as lauric and oleic. This is especially true of sodium (bar) soap made with NaOH versus potassium (liquid) soap made with KOH. If you wash your hair or clothes with a sodium soap that is high in stearic and palmitic and don't rinse well in warm water, then a film of stearic and palmitic soap can remain.

A soap film is not the same as soap scum. A soap film can happen even in super-soft water (water very low in hard water minerals). Soap scum happens when the water contains hard-water minerals.

Ways to minimize soap film are to rinse very well using really warm water, or to reformulate the sodium soap so it is lower in stearic and palmitic, or to use a potassium formulation of the soap. This kind of soap film will be more of an issue with recipes that are high in palmitic and stearic, and not so much in a soap made with a mixed blend of fats. Soap film is also not going to be as much of an issue when just washing the skin because it's easier to rinse skin cleanly. This is going to be more of an issue when washing hair or clothes, because it's harder to rinse hair or fabric as cleanly as bare skin.

 

[not_ally]

That's interesting, DeaAnna. Am I reading the following correctly?

W/soap scum, it doesn't really matter what kind of oils you use, it has more to do with the water; ie; if there are certain hard water minerals in it, they will bind with the oils regardless of what kinds of oils they are (or the difference b/w oils is not significant) in the absence of chelators.

W/soap film, the fatty acids make more of a difference (soft and hard water), soaps high in the "hardening" acids, eg, palmitic and stearic, will create more film, and chelators do not work on that as just rinsing well with warm water.

 

[DeeAnna]

Yep ... you're hitting on all 8 cylinders, Not_ally.

 

[topofmurrayhill]

I did a search for KOH and figured out that I probably couldn't get it locally. Although I found it curious that some ebay sellers (looks like the cheapest place to get a small-ish/8oz test amount) advertise theirs as being "food grade". What on earth kind of food would you make with KOH? I seem to remember a thread here about using lye (not KOH) to boil pretzels, but it just seemed weird to me. No need to answer at length, anyone, I will never do it, it just made me scratch my head.

These alkalis are often used in food preparation or as ingredients. The problem with them is how caustic they are in concentrated solutions, but they are quite non-toxic in dilution. I think the LD50 (a common measure of toxic dosages) for NaOH in rats is higher for table salt.

 

[not_ally]

D, that's actually good news for my lard obsession, I (a) feel like I'm doing as much as I can w/r/t chelators and the scum, and (2) even though lard is kind of high in palmitic/stearic acids, I can always just rinse the film off w/warm water.

TOMH, I think I will forgo further research on KOH and food. I don't think Michael Pollan would approve (jk, have no idea if he would or not, he is the only foodie god I could think of right now.) B/t/w, I was reading a random thread and came across what is now one of my favorite words in one of your posts. Kludge! That is a great, great, word and one I had not come across before.

 

[IrishLass]

These alkalis are often used in food preparation or as ingredients. The problem with them is how caustic they are in concentrated solutions, but they are quite non-toxic in dilution. I think the LD50 (a common measure of toxic dosages) for NaOH in rats is higher for table salt.

That reminds me of the old SNL skit called 'Shimmer Floor Wax' ("It's a floor wax and a dessert topping"! lol): https://screen.yahoo.com/shimmer-floor-wax-000000185.html

Although not in the same way as 'Shimmer Floor Wax', my lye pulls double duty for me, too. My soft pretzels would not taste as awesome without a dip in a lye solution first before being baked.


IrishLass

 

[topofmurrayhill]

That reminds me of the old SNL skit called 'Shimmer Floor Wax'

Excellent.