I learned something important the other day!

[galaxyMLP]

So I was so happy making my 3rd batch of liquid soap and went for a 1% superfat (100% olive oil soap). I was worried it might test lye heavy but it was perfect after the cook (I pH tested)

I diluted my soap paste to about 20% using filtered water. It turned kinda cloudy but since it tested a pH of 8 I knew it was safe. After about an hour of warm diluting it cleared up! When it cooled down though it turned a pearlescent color. It was pretty so I started putting it into my foam pump bottles (also tested pH 8 at this stage)

After filling all 24 bottles that I had, I noticed that the bubbles were not thick or stable at all. It took me 20 minutes to realize that:
1) I have hard water (I thought that water spots in my dishwasher were from detergent and not the water itself)
2) that's the reason this soap doesn't foam but half as much as the one I used distilled water on.

So there you have it. Don't try to use filtered water when diluting liquid soap. I learned the hard way.

To fix it, I boiled it with salt and water and skimmed off the new sodium based soap (Hard bar soap).

I have to make a new batch for the liquid soap of course. But at least I didn't loose a pound of organic EVOO on it! And now I know what I did wrong!

 

[DeeAnna]

Great observations, Galaxy! It takes good attention to detail to pick up on the subtle clues you saw that helped you solve your problem. Nice job!

I did a little test that had about the same results as yours. I wrote it up for SMF here: http://www.soapmakingforum.com/showthread.php?t=52456

 

[galaxyMLP]

Wow! That's so great! I always wondered why Tetrasodium EDTA was in almost all the bar soaps. I assumed it was a preservative. Silly me, I should've looked it up!

I see people referring to you as a chemist. I'm a chemist too! I have a bachelors degree in chemistry and I work as a quality control technician in a chemical plant. Its nice to meet other chem-y soapers out there!

 

[DeeAnna]

Hi, Galaxy -- You're spot-on correct in your thinking! The common usage of the word "preservative" by soapers is a little different than what would be used in industry, but with good reason. The soapers' definition of preservative is any ingredient that kills microbes or inhibits their growth. I'd say that's a subset of what "preservative" means outside the soaping world.

Antioxidants and chelators -- things that preserve by inhibiting abiotic (non-living) processes -- are also technically preservatives, but most of us soapers avoid calling them "preservatives." It gets too confusing to crowd antioxidants and chelators together with anti-microbial ingredients under the overall "preservative" umbrella. We end up with newcomers incorrectly thinking that EDTA (a chelator) or rosemary oleoresin (ROE, an antioxidant) will keep cooties from growing in their lotion, for example, when they really need to use something like Germall Plus (a broad spectrum antimicrobial aka "preservative"). Hope this makes sense!

Tetrasodium EDTA reacts and binds up metals that would otherwise react with the soap itself or the fats in the soap. This "chelating" ability has a couple of benefits. When the soap is used for bathing, the EDTA binds with hard water minerals (magnesium and calcium are the main culprits). When the soap is in storage, the ETDA binds with metals (calcium and copper are two) that are naturally in the ingredients we use to make the soap. Without EDTA, these metals would react with the fats to cause rancidity (aka DOS, dreaded orange spots), so the chelating ability of EDTA lengthens the shelf life of the soap bar. Sodium citrate is another effective chelator that fights soap scum and rancidity.

I'm not a chemist, but my undergraduate degree is in chemical engineering and my engineering career was spent in the chemical processing industry. Also, as a baby engineer many moons ago, I worked as a chem lab tech.

 

[galaxyMLP]

So, I re-made the soap earlier this week with distilled water and it came out great! loved the way it foamed up in those foam pump bottles. Thanks for all of your information.

I knew what a chelating agent was, I just didn't know that tetrasodium EDTA was one. The way you explain things is great!