how much sf?

[venus78]

Hi all,

lately I've been soaping with 25% water discount instead of the usual 38% and I'm happy with the result.

just wondering that should I still do 5% sf or I'd better sf more, like 6%

which do you think is better?

I' prefer more than 5% sf, the less lye the better, I'm just afraid of DOS with higher sf

here's my recipe:

sweet almond 5%

castor 5%

coconut 25%

cocoa butter 15%

olive oil 40%

sunflower oil 10%

water discount 25%

Thanks:smiley2:

[Kitn]

I do a 7% SF but use different oils. I have never had DOS ( touch wood) with this % or recipe.

[Scented]

I've always heard it's safe up to 7%

[MissMori]

What's sf?

[venus78]

super fat

[MissMori]

Ah, I thought it was a chemical that I had no idea about.

I've super fatted up to 12% with no problems. I have a bunch of bars that are over 5 years old that are SF at 8%. No dos, no funky smell, colors have faded a bit, scent varies.

Just my opinion: rancidity has everything to do with the stability of the oils used rather than the SF. If you use oils with a long shelf life, your bars will not get DOS. If you use oils with a short shelf life, your bars may get DOS. You can formulate an awesome bar of soap using oils and butters with long shelf lives. Do I get change from my 2 cents?

[venus78]

I was wondering about how much sf I can do safely with my recipe, I think the only short life oils Im using are almond and sunflower in total of 15% both,

do you think it's ok or I'd better substitute them with longer shelf life oils?

[MissMori]

Natural Oils International has a brief list of the shelf life of oils.

http://www.naturaloils.com

I would go ahead and make your soap with the formula you listed earlier in this thread. Try sf at 7%. Let the bars cure and see what happens. It looks like you have enough oils with a long shelf life. You will never know unless you try.

[venus78]

Ok, will do it. Thanks

[Scented]

Ah, I thought it was a chemical that I had no idea about.

I've super fatted up to 12% with no problems. I have a bunch of bars that are over 5 years old that are SF at 8%. No dos, no funky smell, colors have faded a bit, scent varies.

Just my opinion: rancidity has everything to do with the stability of the oils used rather than the SF. If you use oils with a long shelf life, your bars will not get DOS. If you use oils with a short shelf life, your bars may get DOS. You can formulate an awesome bar of soap using oils and butters with long shelf lives. Do I get change from my 2 cents?

I disagree to an extent. The only time I've had DOS was when it was highly humid.

[chuck_35550]

I thought it had to do with the level of linoleic and linolenic levels in the overall recipe. Aren't those fatty acids found in soybean and other nut oils that break down and spoil, unless they are hydrogenated?

[Scented]

If that were the case, then all of my bars, which contain soybean oil, should spoil, no? And they haven't.

Now the ones that did contain canola, I couldn't keep the DOS away, BUT, it was a very humid summer and my airconditioning unit broke down and for three weeks those soaps had to suffer in high heat and humdity.

Edited September 17, 2010 by Scented

[LovelyLathers]

I SF at 6 to 7% without a problem and lots of my soaps have soybean also. I have gone as high as 10%. I never had DOS on them . I have had Dos in 2 batches neither had rancid oils or high amounts of nut oils, I could only contribute it too was humidity and the heat or I messed up on some wieght of the oils or lye in the batch. They hardened up fine, no zap, but my dehumidifier broke down while I was on vacation. Those 2 soaps were only about 2 months old with high olive oil and beef tallow, about 5% safflower and 5 % castor. I am not at home for my exact recipe. Both made the same day, different FO, I made no other batches that week. Nothing else had dos. Canola has caused dos on my soaps at more than 10% so I stopped using very early in my testing.

[chuck_35550]

So if you stay below a certain percentage of those oils that would keep those fatty acids below a certain profile? I mean, isn't that why we use high oleic sunflower or safflower? Just curious about DOS. Does anyone use REO?

[Scented]

You mean ROE? No. All it does is prolong shelf life on oils that I'm aware of. However, Mike at CF strongly suggests putting a small amount in the oils they carry, which I thought I would try the next time I order from there.

I haven't had a DOS problem for a few years now.

I can't vouch on certain %, because when I used canola it was at 8% I believe. I never went above 8% in a recipe. I did two batches and both of them DOSed within 2 months. I eliminated the canola, opted for the soy at the time, but plan to replace the soy when I run out. Of course I said that the last time and then bought 25 lbs of the stuff lol.

Edited September 19, 2010 by Scented

[LovelyLathers]

I don't use ROE either. I use my oils fast enough it is not an issue. But after the 1st of the year I am ordering double they normal so I probably will add ROE.

[IwantItgreen]

What does ROE stand for? Haven't seen that abb. before

[MissMori]

Rosemary Oil Extract, I'm also seen it listed as Rosemary Oleoresin.

[Abbiepql]

Just my opinion: rancidity has everything to do with the stability of the oils used rather than the SF. If you use oils with a long shelf life, your bars will not get DOS. If you use oils with a short shelf life, your bars may get DOS. You can formulate an awesome bar of soap using oils and butters with long shelf lives. Do I get change from my 2 cents?

If that were true, then in order to avoid DOS those doing CP would be forced to only use oils with long shelf lives? As it can not be determined in CP exactly which oils are going to add to the superfat? Am I correct? If so that takes alot of the challenge out of formulating? LOL

[MissMori]

I wasn't saying we couldn't use oils with short shelf lives. I was saying that you can formulate an awesome bar of soap using only fats & oils with a long shelf life. Cocoa butter... awesome in soap, long shelf life. Olive oil... awesome in soap, long shelf life. Experiment with oils that have a long shelf life and lye discounts/super fatting and you may find out you don't need oils with a short shelf life to give you the desire results you are looking for. Additionally, you may save $$$.

I'm relying on college chemistry taken over 20 years ago and my own research for this reply, so much slack is requested.

I think it's more complicated. It has to do with the chemical bonds of the fatty acid molecules prior to saponification and the chemical bonds of the resulting salts and alcohol (fatty acid salts and glycerin.) Saturated fats have only single bonds, unsaturated fats have at least one double bond along the fatty acid chain. More complicated, the resulting soap could also be affected by the location of the double bond of the unsaturated fatty acid chain.

The single chemical bonds are easier to break. When the NaOH molecule comes into contact with the single bonds of say coconut oil, it is easier for the NaOH to break the the fatty acid chain into the resulting fatty acid salts and glycerin, than it is for the NaOH to break the double bond of an unsaturated fat.

The double chemical bonds are harder to break. The NaOH will first break the saturated fatty acid chain where there are single chemical bonds. This uses up NaOH. Fewer of the double bonded unsaturated fatty acids will be made into fatty acid salts and glycerin.

This leaves the unsaturated fatty acids unsaponified. The double bond in the unsaturated fat reacts relatively easily with oxygen, causing it to become rancid.... DOS. I am not saying that all saturated fats will be saponified and no unsaturated fats will be saponified. I'm saying that there will be more unsaturated fats unsaponified, because of the double chemical bonds. The ratio I can't tell you.

This is why you tinker around with lye discounts. Use more lye and more of the unsaturated fats will be saponified, leaving fewer free to oxidize.

The resulting glycerin also comes into play. Glycerin is hygroscopic. It attracts water from the atmosphere. So, in your soap you have the soap, glycerin, and unsaponified unsaturated fats. The water the glycerin attracts is aiding in the oxidation of the unsaponified fats.

In addition to the above, I think there is something else going on. Yes, the chemical bonds, but also, do you really know the SAP value of every oil you are using? Is that "true" SAP value reflected in the lye calculator you are using? Most lye calculators use some rough average SAP value found somewhere, who knows where. I think to be "safe" most lye calculators are programmed with SAP values that will underestimate the amount of lye necessary to fully saponify a given oil. Do you test each of your oils for SAP value? They do change from manufacturer to manufacturer and year to year. How much? I don't know because I don't test my oils.

In a perfect chemical reaction, every fatty acid chain would be broken apart by the exact number of NaOH molecules, leaving no unsaponified oil and no extra NaOH molecules. This would be 0% superfat/0% lye discount. We don't do that. We want extra oil in our equation. We purposely use less NaOH than is necessary. So, factor this in with a lye calculator that already underestimates how much lye you need and you have perhaps too many unsaponified oils. Eventually, those oils will go rancid in the soap. How long? That I can't tell you. I've made castille soap that took 3 years to get DOS. I've made soap with walnut oil that got DOS is less than 2 months.

There was a reply saying humidity was causing DOS. We are probably talking about different sides of the same coin. I think it's not really the humidity, but the glycerin attracting water to the soap creating an environment for the unsaponified unsaturated fats to oxidize... that would be caused by the humidity. In a relatively "dry" environment would the same soap get DOS? I would say yes, given more time. This is where the shelf life of the oil comes into play.

Or perhaps not.

[chuck_35550]

Excellent explanation on this subject. I would be interested to hear from Top (where is he anyway) to see if he might expand the explanation a bit more. I have never had DOS but then and again I don't use formulas with high amounts of short shelf life oils. I had totally forgotten the glycerin element in this equation and that in itself is very interesting.

Thanks MissMori

[MissMori]

Chuck,

I'm not a chemist, so I'm reporting what I've found through my own research.

Something else that may be effecting the soap is phenols in the oils. Some phenols are germicidal and used in formulating disinfectants. Interesting! I'm not sure if the phenols found in specific oils (olive for one) are assisting in preventing DOS. More research to do.