Lemon juice alters SF - HOW?

[WillZ]

I've been searching the forum for anyone substituting part of the water with lemon juice. What I found is that it alters the SF. But can anyone tell me in what way the SF is altered? I assume that the SF is lowered, but is there a formula like 10% lemon juice will change the SF by -1?

 

[shunt2011]

Here's a previous thread on the subject here in the forum:

https://www.soapmakingforum.com/threads/lemon-juice-in-place-of-water.60156/

 

[DeeAnna]

Acids such as the citric acid in lemon juice RAISE the amount of excess fat in soap (in other words -- higher superfat).

Acids (citric acid, fatty acids, etc.) want to react with alkalis (in other words -- NaOH). Stronger acids (citric) will react first; weaker acids (fatty acids from your soaping fats) get to react with what's left over.

By making soap with more acid molecules (fatty acids + citric acid) than alkali molecules (NaOH), the stronger acid (citric) will consume what alkali it wants, and the fatty acids will react with whatever alkali is left over. Because there won't be enough for the fatty acids, your soap will have more fat and/or fatty acids than what you expect. In other words, the superfat will be higher.

The solution is to add sufficient alkali to sufficiently react with ALL of the acids in your soap pot.

More info about using the more common acids in soap: http://classicbells.com/soap/soapystuff.html

 

[BrewerGeorge]

There's a relatively famous video about this, if it's still posted.

Nobody has yet asked WHY you want to add lemon juice. If it's to generate sodium citrate as a chelator, that's one thing. If you're going for any kind of lemon characteristic in the finished soap, this isn't the way to make that happen.

 

[MySoapyHeart]

There's a relatively famous video about this, if it's still posted.

...

It is. If this is the one you meant?

 

[dixiedragon]

Yup - the lemon juice will gobble up a portion of the lye. what is your goal here? if you want lemon scented soap, lemon juice won't do it.

 

[earlene]

The problem with that video is that it uses the lemon pulp/rind/pith and concludes with 'you can't make successful soap with lemon'. It does not address the question at all about making soap with only lemon juice.

Many people have made successful soap with lemon juice, me included. Anne Watson has a recipe in one of her books that makes a successful citrus soap.

The questions about accounting for SF have already been addressed, so I won't go into that. I just wanted to point out that that particular video is not a good response to questions about using lemon juice. It might be a useful inclusion for discussions about using lemon or any other citrus pulp in soap, however.

Sometimes we as soapers want to try anything and everything, just because we can, and don't necessarily have a particular goal in mind. Sometimes we just want to see what will happen. I tried lemon juice because I saw a video of a soapmaker who used lemon juice in her soap. She made huge batches of soap and used what looked like a full bottle of lemon juice in her huge soap pot. The video showed the soap from start through the cutting, so it was obvious that she made hard enough bars of soap using lemon juice. She didn't really go into to why, for what purpose or any detail about SF, but she said her family loved the soap and so did her customers. I thought my son might like soap with lemon juice in it and added lemongrass FO for fragrance. True, I didn't know what SF I ended up with, but the soap was nice enough and he did like it.

Eventually I started to pay more attention to the technical details and learned how to adjust for SF, etc. So kudos to WillZ for looking for answers so soon in the process!

 

[DeeAnna]

I use the Soaping 101 video to make the point abundantly clear, because there are some soapers who have the attitude "if it doesn't look wrong, it isn't, so why do I need to care?" So I use the video as a visual example that shows how bad it can be. But, yeah, it's extreme and I doubt most soapers ever go that far.

By using all lemon juice in Ann Watson's Citrus Soap recipe, I estimate the lye discount would be increased by about 10%. So if you set the superfat in Soapee at 5% and use high purity NaOH, the actual lye discount is closer to 15%. Will that extra superfat change the appearance of bar soap? Most likely not. Would it mess up liquid soap? Most likely it would -- you'd get a thick layer of fat or fatty acids floating on the soap.

 

[MySoapyHeart]

I just wanted to point out that that particular video is not a good response to questions about using lemon juice.

Ok, I am sorry, I just wanted to help as I have seen the video and found it relevant to this topic when BG brought it up. I`ll gently bow out and go to bed, it really has not been my day (or week) anyway, ugh

Take care

 

[BrewerGeorge]

...
By using all lemon juice in Ann Watson's Citrus Soap recipe, I estimate the lye discount would be increased by about 10%. So if you set the superfat in Soapee at 5% and use high purity NaOH, the actual lye discount is closer to 15%. Will that extra superfat change the appearance of bar soap? Most likely not. Would it mess up liquid soap? Most likely it would -- you'd get a thick layer of fat or fatty acids floating on the soap.

And the thing some people don't quite seem to realize is that there will no longer be lemon in the finished soap. There will be some amount of sodium citrate, some sugars, and a bit more unsaponified oil than there would otherwise have been.

We know lye changes almost everything and don't think twice that it changes oils to soap, but seem to want to ignore that effect in this case. And while denaturing a few proteins or oxidizing some sugars in a milk or or beer or some aloe is one thing, a strong base to weak acid reaction is another thing entirely. The former might pass on some characteristics, but the latter makes water and salts.

 

[BrewerGeorge]

Ok, I am sorry, I just wanted to help as I have seen the video and found it relevant to this topic when BG brought it up. I`ll gently bow out and go to bed, it really has not been my day (or week) anyway, ugh

Take care

I don't think that was meant as critically as you seem to have taken it. DeeAnna's response above is pretty much the same point I was trying to make by referencing the video I was too lazy to find and link. I, for one, appreciate your enabling my laziness.

 

[dixiedragon]

I also think that video is helpful.

Willz, I ask what your goal is, not because you can't make a soap with lemon juice, but because a different goal might mean we make different suggestions. If you just want to try making soap with lemon juice, cool. But if you want to make a soap that smells lemony, then lemon juice won't get you there.

 

[earlene]

I do not ever mean to make people feel bad. I am sorry for causing strife. It's just that I do feel that video should include a caveat about the fact that it is not about using only lemon juice, particularly when the question is about using lemon juice. So please do not take my post as a criticism of any of you. If I posted something that should have included a caveat, I would hope someone would point that out as well.

 

[Rune]

Another point of using lemon juice is for a natural color. I did that and became an nice orange color. I added a tiny bit of turmeric as well to boost the color. Or, well, actually I added orange juice and zest, I think. No lemon. But I guess it goes for somewhat the same. It will give a nice color to your soap. But the lye amount must be adjusted up with a gram or two or three or four, depending on the amount of citrus you add, what citrus - lemon, oranges, lime or other, and in what form - freshly squeezed, from concentrate or other varieties.

 

[earlene]

I have used lemon juice in soap and didn't really notice it adding color to the soap I made, but I also used a fragrance that does discolor, so I could actually be wrong about lemon juice not discoloring the soap. In any case, it did not turn yellow per se, more a beige-ish sort of color.

 

[Rune]

Yes, maybe it doesn't add a color after all. I totally forgot that I also added a small jar of baby carrot puree. I had it blended into my oils. My lye water was very orange. But I did use orange juice with a tiny, tiny amount of turmeric, not lemon juice. Since you had a beige-ish color, it must be orange juice that can act as a natural colorant, and not the lemon. I originally thought both lemons and oranges would make a yellow soap. And that seems to be not true.