test bars of additives

Updated: Lather Lovers Additive Tests, One Year Later!

soap science and info

In 2012, I participated in the Lather Lover's Additive Testing swap on the Dish Forum, hosted by the fabulous Shannon of Scenter Square. I kept the samples from the testing for a couple years after the initial tests, and ran follow-up lather tests in 2013 and 2014 before I threw away the soaps. Recently, I found my photo archives and notes from the 2013 lather testing, and realized I never wrote a formal follow-up to the 2012 tests! It's time to fix that up!

This is a follow-up with the results of the testing from 2012 and one year later, in 2013, side by side!

As a reminder, here's how this swap worked:

Each of the soapmakers made the control formula with the addition of one additive during the week of January 1st, 2012. This ensured all the soaps were of similar age and formula, leaving the additive the only major variable between each bar. 

 The recipe used to test the additives, all soapmakers used exactly the same recipe.)

Each soapmaker received a bar from every other soapmakers batch, leaving us with almost 30 different bars and additives to test and ponder.

 The original samples from the Lather Lovers swap in 2012

We tested the additives listed below (the method of using the additive is in parenthesis):

  • Control Formula (8% superfat)
  • Control Formula (5% superfat)
  • Sodium Lactate (0.25 oz of SL per pound of oils)
  • Granulated Sugar (1 tablespoon per pound of oils)
  • Honey (1 tablespoon per pound of oils)
  • Silk (This sample was lost in the mail during the swap)
  • Rosin (Used as a 3% additive)
  • Bentonite Clay (1 tablespoon per pound of oils)
  • Tetrasodium EDTA (0.5% per pound of oils)
  • Powdered Goats’ Milk Powder (Reconstituted, and substituted for 100% of the full water)
  • Aloe Vera Juice (Substituted for 100% of the full water)
  • Canned Coconut Milk (Substituted for 100% of the full water)
  • Powdered Coconut Milk (Reconstituted, and substituted for 100% of the full water)
  • Beer (Substituted for 100% of the full water)
  • Fresh Goat’s Milk (Substituted for 100% of the full water)
  • Canned Evaporated Milk (Substituted for 100% of the full water)
  • Powdered Sugar (1 tablespoon per pound of oils)
  • Kaolin Clay (1 tablespoon per pound of oils)
  • Cetyl Alcohol (Used as a 3% additive)
  • Oat Milk (4 ounces in a 24 ounce batch)
  • Yogurt (Substituted for 58% of the water)
  • Sorbitol (Used as a 5% additive)
  • Sodium Citrate (Used as a 3% additive)
  • Palm Kernel Oil (Substituted for the Coconut Oil)
  • Kefir (Substituted for 58% of the water)
  • Sodium Citrate & Sorbitol (Combined additive)

Lather Lovers Additive Testing in 2013

In April of 2013, I hauled out my samples and retested them, the same way I tested them previously. Each soap was stored in the original packaging, under my bathroom sink, for one year. Many samples developed DOS, and other testers have reported which samples developed DOS as well. I'll include those notes below.

 In 2013, I retested the samples from the 2012 swap to see how they compared.

Sample 1: Control Formula (8% Superfat)

2012 testing notes: I don't often use olive oil in soapmaking (I know, gasp!) and it's been years since I soaped this simple holy trinity formula that is so popular in soapmaking. All it took was this little reminder why: scant lather and a slimy feeling.

 The Control Formula (8% Superfat)

2013 testing notes: The soap does not feel as slimy as I remember, but it still feels icky to me. The lather is certainly better now that the bar has aged a year.

Another tester's used sample developed DOS, but the conclusion was that the soap was in contact with a metal bath caddy and the DOS appeared in line with the contact points of the metal. (A good reminder that metal and soap are not friends!)

Sample 1a: Control Formula (5% Superfat)

2012 testing notes: It's a no brainer that lowering your superfat leaves less free oils in the soap, which therefore should increase your lather. I was actually a little surprised as to how much it increased lather!

 The Control Formula (5% Superfat)

2013 testing notes: The lather was slightly creamier than previously, but otherwise, I didn't notice much of a difference on this bar.

Sample 2: Sodium Lactate

2012 testing notes: I've often read that soap made with sodium lactate is easier to cut, crumbles less and lasts longer in use because of the hardness imparted by the additive. I've never bothered to use it, I'll be honest. However, the sample does seem SLIGHTLY harder than the other samples (but not by a ton) and it did up the lather factor a bit.

 Sodium Lactate

2013 testing notes: The lather was slightly creamier and tighter than previously, but otherwise, I didn't notice much of a difference on this bar. I still don't have much experience with sodium lactate in soaps, this testing didn't do anything to really inspire me to use it!

Another tester's used sample developed a small spot of DOS on one corner. Mine appeared fine.

Sample 3: Granulated Sugar

2012 testing notes: I've always considered the adding sugar to your soap to increase lather one of those little soapmaking myths - sort of. Fruit juices in soap seem to up lather, so it makes sense that sugar would do it. But I've heard soapmakers claim that it makes for huge thick phenomenal lather, which is probably why I thought it was a little over the top. It did seem to increase the lather, but not any substantial amount worth bragging over.

The discoloration at the top of the bar was from another sample that was wrapped in dark tissue paper.

 Granulated Sugar

2013 testing notes: The lather was much creamier and tighter than previously, but the soap did develop a little bit of DOS after one year. You can see a visible spot of DOS to the middle right on the front of the bar. No other testers reported DOS on their used samples of this additive at the one year mark.

Sample 4: Honey

2012 testing notes: I was actually a little surprised at the difference here. The honey made the lather creamier and silkier in feeling, but not much more abundant.

 Honey

2013 testing notes: After a year, the lather improved greatly - there were more bubbles and the lather was dense, thick, and lovely.

Sample 6: Rosin

2012 testing notes: Gigantic round of applause for the soaper who made this sample, as rosin is notoriously known for being a pain in the butt to soap. But look at those bubbles!

The downfall? It's drying. Really, really drying.

 Rosin

2013 testing notes: The lather changed a little - it's denser with smaller bubbles, but still abundant. The rosin soap sample still leaves your skin feeling tight and dry, though.

Another tester's used sample developed a small spot of DOS. My own sample had a mottled look, but I believe that was from the dark paper wrapping that discolored the bar (plus the discoloration the rosin contributed.)

Sample 7: Bentonite Clay

2012 testing notes: Many soapmakers add various clays to their soaps to increase slip and glide, to make shaving soaps. It also adds a nice creamy touch with an increase on lather. The biggest thing I learned from this sample testing is how quick the lather started up and levelled out - there isn't much difference between the 10 second and 20 second marks of use.

 Bentonite Clay

2013 testing notes: I didn't notice much of a change between the first test and the second test, though it looks like the lather is ever so slightly denser than it was originally. I have heard from some wet shavers that they don't actually like when a bar of shaving soap contains clay, as it supposedly dulls their blade faster.

Sample 8: Tetrasodium EDTA

2012 testing notes: Another additive I've never tested on my own, Tetrasodium EDTA counteracts the defoaming action of hardness ions, reducing soap scum and improving lather according to Lotioncrafter. Seems it works!

 Tetrasodium EDTA

2013 testing notes: I didn't notice much of a difference between the 2012 and 2013 testing.

Another tester noted strange discoloration after a year and a half on their used sample - the entire back and the top/bottom edges turned a deep orange color, similar to DOS. My own used sample looked the same as it did from the beginning.

Sample 9: Powdered Goat's Milk

2012 testing notes: I was a little taken back that this sample was powdered goat's milk. (I washed while Brian took photos, and he was the only one who could check what a sample was.) I remember specifically asking him what this was as I washed with it: it smelled off and was scant on lather. Once the lather built up, it got thicker and creamier but never bigger.

I really didn't notice too much of a difference between this one and the control besides the lack of slime in this soap's lather.

 Powdered Goat's Milk

2013 testing notes: This particular sample seemed to lather quicker than it did originally, but otherwise, didn't seem much different than the original round of tests.

Multiple other testers' used samples developed DOS. Mine does not show any signs of DOS, however, it doesn't smell "right." Interestingly enough, Shannon had a spare unused sample and it did not show any signs of DOS in comparison.

Sample 10: Aloe Vera Juice

2012 testing notes: This was my sample, and I was thoroughly excited about it. Love the results, and will be incorporating it into a couple of my soaps in the line. It was the perfect balance of increased lather - not just creamy, not just bubbly, but a little of both.

 Aloe Vera Juice

2013 testing notes: Another sample that I didn't notice much of a different between the 2012 and 2013 testing. Aloe vera juice is still one of my favorite additives in cold process soapmaking.

Sample 11: Canned Coconut Milk

2012 testing notes: This soapmaker made two samples, one using canned coconut milk and one using powdered coconut milk, since the ingredients differed. The canned coconut milk used in this sample contained guar gum and it seemed to make a small difference between the two coconut milk samples.

 Canned Coconut Milk

2013 testing notes: Like many of the follow-up tests, the lather became thicker with smaller bubbles. I think the amount of lather also increased slightly after the sample aged.

Shannon's used sample had a small dot of DOS next to the stamped number. I'm not sure what the soapmaker used to stamp the soap (a metal or plastic stamp?), but it would be interesting to know if that had an effect on why it developed DOS. Shannon's unused extra sample, stored in its original packaging, did not have any DOS.

Sample 11a: Powdered Coconut Milk

2012 testing notes: This soapmaker made two samples, one using canned coconut milk and one using powdered coconut milk, since the ingredients differed. The powdered coconut milk used in this sample contained no extra ingredients, and it seemed to have more abundant lather than the canned coconut milk.

2013 testing notes: At first, the lather didn't seem to change at all, but as I continued to use the soap sample, the lather stayed creamy and tight without increasing as much as it did during the first test.

Sample 12: Beer

2012 testing notes: Everyone knows beer soap lathers like a mofo. And here's the proof. :)

 Beer

2013 testing notes: It's interesting that after a year of aging, the beer soap sample seemed to have a little less lather than it did originally. It's still a huge improvement compared to the control sample, though!

Sample 13: Fresh Goat's Milk

2012 testing notes: The difference between the fresh goat's milk and the powdered goat's milk is pretty obvious. This is what I expected from both samples!

 Fresh Goat's Milk

2013 testing notes: After a year, the lather was more lotion-like and extremely creamy with hardly any visible bubbles.

Another tester reported that their used sample developed DOS after a year. Mine seems fine!

Sample 14: Canned Evaporated Milk

2012 testing notes: I didn't really know what to expect here, as it never crossed my mind to use canned evaporated milk in soap. Buttermilk? Sure. Coconut milk? Sure. Goats Milk? Sure. But this? Well, you can't say soapmakers aren't a creative bunch.

I didn't like the look or feel of this bar, but the lather speaks for itself.

 Canned Evaporated Milk

2013 testing notes: During the follow-up test, I was surprised how much tighter the lather became as compared to the original lather test. The abundance of lather seemed to slightly increase, as well. The original sticky feel that threw me off is no longer present - it simply feels like a normal bar of soap.

Another tester reported that their used sample developed DOS, however, I did not find any indications of DOS on mine (both visually and smell-wise.)

Sample 15: Powdered Sugar

2012 testing notes: The powdered sugar sample gave a slightly creamier lather than the granulated sugar sample. Powdered sugar is simply finer ground granulated sugar with added starch to prevent caking, the added starch must have made for the lather difference. Now I wonder how adding cornstarch or another starch would affect lather on its own.

 Powdered Sugar

2013 testing notes: The lather on the follow-up test was much thicker and denser than it was originally. All of the larger bubbles present in the original test are gone, leaving only a foamy lather.

Another tester reported DOS on their used sample after a year. Again, mine appeared fine without any indication of DOS.

Sample 16: Kaolin Clay

2012 testing notes: Quite a difference between the clay samples! Kaolin clay was slower to lather up, but stabilized at a much thicker abundant lather than bentonite clay did.

 Kaolin Clay

2013 testing notes: This sample is much darker than it was originally, and that's likely attributed to the oxidation of the bar. There were several spots of DOS (you can see some of the spots to the left and right of the engraved 16) and the entire bar is a dark tan color with an orange undertone as compared to the original.

All of the testers who followed up after a year reported DOS on their used samples. Shannon's unused extra sample, stored in it's original packaging, did not have any DOS.

Sample 17: Cetyl Alcohol

2012 testing notes:

First things first, DOS. For some odd reason, this little guy had a few spots of DOS. And we all know how I feel about DOS - ew, ew, ew, ew. I'm not sure if it was the additive that caused this, the curing conditions, the oils, or what...

That being said, a very small difference on the lather from the control. A consumer wouldn't notice the difference, I don't think.

 Cetyl Alcohol

2013 testing notes: The follow-up test was a major ick-factor for me. (The things I do for y'all...) The lather felt somewhat slimy, but I can't tell you whether that was influenced with my own gag factor of using soap covered in DOS.

All other testers who followed up after a year also reported DOS on this sample. My original sample had DOS, so I expected this one. (And was dreading it...)

Sample 19: Oat Milk

2012 testing notes: Oat milk! The lather felt just as silky and creamy as other milks, and produced about the same lather as the fresh goat's milk sample.

 Oat Milk

2013 testing notes: After a year, the lather appears to have decreased! What lather there is is very scant and builds into a foam rather than bubbles.

Two other testers reported DOS on their used samples. Shannon's unused extra sample, stored in it's original packaging, did not have any DOS, nor did my own used sample.

Sample 20: Yogurt

2012 testing notes: I can't describe the smell on this one, but I didn't like it.

Slightly creamier lather, but not a huge difference in abundance than the control. Slightly better, in my opinion - not worth the trouble.

 Yogurt

2013 testing notes: I didn't notice much of a difference between the original test and the follow-up test. The sample still smelled faintly weird during use.

Sample 21: Sorbitol

2012 testing notes: Everyone should recognize Sorbitol from an ingredients list of melt and pour soap. My understanding is that it's usually used in transparent soap to keep it clear, as well as to improve lather and conditioning. Looks like it does that, to me. :)

I had a hard time keeping all the lather in my hands, it was just that abundant.

 Sorbitol

2013 testing notes: I wasn't sure whether the lather would hold up after a year, but it did! Like many other samples, the lather was slightly denser with smaller bubbles, but it was still extremely abundant.

Sample 22: Sodium Citrate

2012 testing notes: Most often used for the same reason Tetrasodium EDTA is: to cut down on soap scum. But holy moly, look at the lather.

Another sample I had a hard time keeping control of the lather, I'm pretty sure my the 20 second mark I had dropped some of the lather in the sink.

 Sodium Citrate

2013 testing notes: The lather decreased a bit over time on this one. I didn't have an issue containing all the lather in my hands this time around, and the lather itself was thicker and more foam like.

Sample 23: Palm Kernel Oil Substitution

2012 testing notes: I use PKO a lot because I love what it does in soap. I think the difference of using it versus Coconut Oil is pretty statement worthy.

Oftentimes, people tell me that PKO will not increase lather more than CO, that it will be creamier than CO lather. Substituting PKO for CO in this formula resulted in more lather, I'd say double the lather of the control (however, the control was so scarce when it came to lather for me!) I would agree that is SLIGHTLY creamier, but not by much.

 Palm Kernel Oil Substitute

2013 testing notes: The bigger bubbles in the original testing never showed up in the follow-up! Since these tests, I've gone palm-free and have started relying entirely on fatty acid profiles for formulating. (Meaning I no longer have a confirmation bias about PKO!)

Shannon's used sample developed DOS, however, the unused sample stored in its original packaging did not. Mine appeared fine.

Sample 24: Kefir

2012 testing notes: More lather than the control at first, but not much more at the 20 second mark. However, it is creamier. :)

 Kefir

2013 testing notes: Another sample where the difference between the original test and the follow-up test were minimal, with the only change being that the bubbles were smaller.

My used sample developed a small spot of DOS on the bottom right corner of the face of the bar. Another tester reported DOS on their used sample after a year, as well.

Sample 25: Sorbitol and Sodium Citrate

2012 testing notes: Considering how sorbitol and sodium citrate performed on their own, I expected slightly better lather here. But it's still pretty impressive.

Another that I'm sure I dropped some suds in the sink around the 20 second mark.

 Sorbitol & Sodium Citrate

2013 testing notes: I expected the lather to hold up a little better than it did after a year! I didn't have as much trouble containing the lather this time around, and the bubbles, again, were much smaller than the original tests.

Lather Lovers Additive Conclusions

It was definitely interesting to be able to compare the first tests in 2012 with the follow-up tests in 2013. I also did tests of some of the samples in 2014 before tossing the samples out. The 2014 tests didn't show very many differences with the 2013 tests so I didn't catalog them.

One of the things that this round of testing reinforced is the importance of using distilled water in soapmaking, keeping soap in its packaging until use, and not exposing it to metal. Shannon had many unused samples stored in their original packaging, and none of them developed DOS. However, many of our samples, which had been used in tap water, developed DOS, and those that were exposed to metal also oxidized. If we had used our soaps in distilled water rather than tap water, I bet there would have been less DOS.

The second thing that I found interesting was that, generally, a year of aging made the lather denser and thicker than it was originally. For the most part, lather abundance was the same in the follow-up test, but the bubbles were smaller and tighter, rendering more of a foam lather. Even more interesting though, was that in some cases, lather boosting provided by the additive was temporary. Over time, some of those additives actually showed a decrease in the original lather boost.

My favorite thing about this swap was being able to see how different folks got similar or different results, depending on the additive, method of using the soap, and the type of water they used when washing with the sample. It also provided a wealth of reference material for when soapmakers pass on those claims of huge abundant lather thanks to an additive. In some cases, there was an increase or change in the lather, but for the most part, I don't think there are as many magical lather boosters as the soapmaking community claims!

What was your most valuable takeaway from seeing these tests play out over time? Are there any additives you will or won't try out after seeing the results? Let me know in the comments!

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