"...So it might be FAs produced during the chemical reactions, which help stabilize the whipped nature of the 'butter'? That's a fun fact (if I am understanding you correctly.)...."
The recipes I'm finding on the internet for laundry butter call for adding borax (and washing soda) to pre-made bar soap that's been dissolved in water. Here's one:
http://www.ibelieveicanfry.com/2014/12/homemade-laundry-butter.html If that's how laundry butter is usually made, I really do think the borax is breaking down the finished soap and the fatty acids are helping to thicken the mixture.
***
I don't make laundry butter -- and now that I've been looking at various recipes, I doubt I ever will.
Based on the info from the above link, there are only 1.2 grams of actual soap added to each load of laundry. (My basis -- she says to use 5.5 oz of soap to make a 2 quart batch of laundry butter and use 1 TBL butter per load of laundry for a total of 128 loads.)
I use roughly 5 grams of soap each time I take a shower -- how can I get a load of grubby laundry clean using only 25% of that amount of soap???? Even if I use twice that amount of laundry butter, that's still less than half the soap per load of laundry than I would use for bathing!
So first thing, I don't see there's remotely enough soap added per load to do much if any cleaning. And if some of the soap has been turned into fatty acid by reacting with the borax, that reduces the miniscule amount of soap even more.
Here's a report from one user who is not pleased with laundry butter:
http://somedaywewillsleep.com/i-used-my-own-laundry-butter-for-12-months-and-heres-what-i-learned/
And here's a blog post from another user who insists the butter works, but also recommends pretreating stains before washing. While pretreating stains is not a bad thing, if a person has to pretreat most stains to get good results, that's telling me the pretreat is doing the cleansing, not the laundry butter.
http://ladybugwrites.com/2016/02/03/homemade-laundry-butter/
This is the recipe I use with my own 0% CO bar soap made expecially for this. It does say 1 TBL. I probably use about that per load, maybe a bit more, maybe a lot more, depends on the load itselt. I always divide part of it into 2 parts; one part goes into the pre-wash & 1 part goes into the main wash. I wipe the spoon off onto a rag or towel or some piece of laundry in each load (to prevent waste & clean off the spoon.) I always use pre-wash. And I always use a second rinse. I always use warm water wash with cold rinse. My washing machine doesn't have the warm/warm option, or I would use that. I have never like cold/cold for laundry.
The reason I use extra rinses and so forth is because long ago I read an article by a large hotel laundry manager about how to keep hotel linens clean, white, fluffy and absorbent. This was the gist of it: Hot water, minimal detergent (not excessive as it builds up in the fabrics), extra rinse (to remove excess soap), NO fabric softeners (they inhibit absorbency and also build up in the fabric over time). So that's the way I wash all my clothes. Except for the Hot/Hot, as it is not an option on my machine, so I settled for warm/cold.
For 10 or 15 years previously I used my own homemade powdered laundry detergent using Fels Naptha &/or other bar soaps finely grated and mixed with washing soda, oxiclean, & Borax. I found the Fels Naptha to be far too strong and colors faded quickly. But it was good for really grungy laundry (heavy-duty dirty workclothes, etc.)
To quote our Infection Control Nurse at the hospital where I worked most of my Nursing career: '
Friction is the most important part' of hand washing. She was speaking of removing unwanted germs in the context of Infection Control, of course. But the same is true for dirt and grime. Soap and warm water facilitate cleaning, but without friction it is not nearly as effective. I have found that to be true in laundry as well as hand washing. When I hand wash laundry, which I often do while traveling, I can absolutely confirm that soaking in soapy water will not get a washcloth with make-up clean, but hand washing with friction does remove the make-up from the wash cloth extremely well. (My grand daughter can't seem to remember to use make-up removal pads.) So it's not just the soap in the washing machine that is doing the cleaning, the machine itself is helping as well.
Of course for fine delicates as the OP plans to wash, one doesn't want vigorous agitation as one does for towels. And a gentler soap as well. In my youth I used to hand wash all of them in special soap from Victoria Secret. But I am no longer young and no longer wear such fine delicates. I wash it all in my regular laundry butter now and am happy with the result.
I am making a laundry soap to wash wool and silk.
I decided of 33% Palm oil, 33% Olive, 33% coconut. 0% super fat. Adding a dash of turpentine, and borax at trace. How much borax per pound goes in at trace? What does Borax do to the soap? I understand it softens the water.
In this recipe I also use one teaspoon of salt, and sugar per pound.
I will be doing CP OP. Is that a good idea?
What can I do to make an extra hard bar.
sephera, I am curious how you will be washing the wool and silk using this soap. Is it bar soap you will make, then grate it into a powder? Will you be hand washing your delicates?
When I was young I used specialty soap for delicates that I bought at Victoria Secret, but it was a liquid. Occasionally I also used Woolite, which came as a powder. But I preferred the liquid from Victoria Secret.
Long ago I stopped bothering with fine delicates and hand washing my undies unless I am staying in hotels without laundry service. Now I just use dish washing liquid or hotel shampoo to wash my undies when in those situations. Or at home, I just use my regular laundry butter in the washing machine.
But I don't wear silks any more and never washed them myself anyway. They went to the dry cleaners. Woolens are another item I rarely bother with anymore, so I am probably no help with how well any of these water-based cleaning soaps would work for wool. My extent of using wool is felting it, which is probably not what you want to happen to your woolens.
If you go to the Borax site (and others), it states that Borax boosts the cleaning power of your laundry detergent (or soap). My guess is that it does that by softening the water.
What can you do to make an extra hard bar?
1. Use a higher lye concentration (less water) and you will get a harder bar sooner. I don't think it changes how hard the bar is at the end of cure, though. I believe it just speeds up the process.
2. Salt is supposed to help harden bar soap. I cannot verify that I have noticed a great difference, but I do it sometimes anyway. (1/2 tsp ppo dissolved in water before adding the lye to the water)
3. Sodium Lactate is supposed to harden soap and minimize shrinkage. (usage recommendations vary - check the
lye calculator MMS for correct amounts for you particular recipe) More info
here.