Questions on rebatch soap

[allybee]

Hello all!

My first post to this forum; I have been regularly prowling about it for the past 2 weeks and I love how helpful everyone is. Hope you can help a newbie like me with some questions.

So my favorite types of scents are bright, light, citrsy/floral types, very much "top note" heavy if you will. However, I recognize that these fade pretty quickly in CP soap and I haven't had much luck with getting them to stick (I was especially disappointed when my pikake jasmine scented soap--my all-time favorite scent--faded from wonderfully fresh and floral to tropical-themed play-doh within a week). I did some research and it seems that a lot of this is due to the fact that saponification can change the structure of certain aromatic chemicals in the fragrance oil and alter their scent. It also seemed like the general consensus was that melt-and-pour soap holds top notes better since saponification is complete. Well this got me wondering: does rebatch soap also hold bright fragrances better? If it turns out that it doesn't then I don't want to wait twice as long for my soap to be ready for the exact same product. Additionally, I've enjoyed replacing all of the water in my recipe with frozen oat milk and, since I keep everything so cold, I haven't had too much of a problem with discoloration but I'm worried that by heating up the soap to rebatch it, the sugars will caramalize and the soap will brown. If that's the case, I'll need to ditch the milk and just stick with sorbitol.

So I guess my questions are:

1. In your experience, does rebatch soap hold fragrances better, specifically light/bright fragrances with strong top notes?

2. What's the minimum amount of time I should wait before rebatching to ensure that saponification is 100% complete and that the fragrance won't be impacted?

3. If I rebatch milk soap, will the heat discolor it?


Thanks in advance!

 

[Todd Ziegler]

I can't answer your rebatch question because I don't rebatch my soap failures. However I will point out for you that there are a lot of citrus FO's that have plenty of staying power but they are expensive. For example; awaken from nurture soap remains strong in my soap. I have a 3 month old one that still has a great lemon fragrance, not like the day after but still enough to get a good whiff of lemon. And I mention this because I force gell my soap to a minimum of 150°F for at least 30 minutes and above 140°F for an hour. There are many other FO's that have citrus or fruity top notes that stick around for a while.

To get them it's going to be expensive but you pay for what you get. They awaken FO is around $46 per pound and some get higher than that. You will want to get the best FO that you can afford. In the beginning I thought I could buy the cheaper FO's from ebay and Amazon but I ended up with soap that didn't have any fragrance after a few days or worse the cheap FO's caused my soap to accelerate or seiz up almost instantly. Not all FO's from ebay and Amazon are bad but the majority are.

So buy the best that you can and you won't need to rebatch in order to get a lasting FO, if it will even work, which I am sure someone will be able to help you with.

 

[dibbles]

Hi @allybee and welcome to the forum. I'm in the Minneapolis area too. I hate rebatching so I can't help you there, but @Todd Ziegler is right - there are FOs that will stick. If you haven't found it yet, here is a link to the SMF Fragrance Oil Review Chart SMF Fragrance Oil Review
This can be a helpful resource. Reading reviews on supplier's sites can also be helpful. There are a lot of FO addicts here (I count myself among them), so you can start a thread in the fragrance forum section with a 'In Search of....' title and will likely get more specific answers.

 

[maryloucb]

From what I understand people do rebatch so that they can add delicate fragrances and they won't be affected by the chemical process of saponification. I have rebatched once to try and correct a scent that I did not like (I had orange and cedarwood essential oils and I really did not like the scent of the cedarwood, so I rebatched and added more orange) and I can only say that it's a pain, and I probably won't do it again, but that's just my personal experience. I think the advice above is good--get good quality EOs or FOs and play around with what sticks.

 

[AliOop]

Great answers from Todd and Dibbles regarding FOs sticking.

I have rebatched a LOT of soap in the past, and occasionally still do. I do add additional fragrance to my rebatches to compensate for the loss of scent strength when reheating the soap.

I also used to HP a lot, which is basically similar to rebatching, except that all scent is added at the end of the cook (instead of just the additional scent).

In both situations - rebatch and HP - the scent usually sticks more than it does in CP. But if a scent fades in CP, it will eventually fade in HP or rebatch, too.

Some people have good success with using clay to anchor their scents, while others don’t see a difference. Lots of good threads here will explain that if you want to search and read about that.

Regarding milk soaps (and other soaps with sugar content), rebatching has never caused mine to darken, probably bc the sugars have already “cooked” during the saponification process. That’s my personal guess and not a scientific explanation as to why no darkening occurred.

I saved your second question for last. You don’t need to wait for complete saponification to rebatch. It will be easier in fact if you don’t. The more water that remains in the soap, the faster the rebatch will go.

Also, while fragrances are somewhat affected by lye and the saponification process, they don’t “saponify” in the way that oils do.

So I think you are conflating two unrelated issues here. Yes, your fragrance will be affected (weakened somewhat) by the additional heat from rebatching. But I don’t personally think that timing the rebatch to occur after full saponification will affect the scent strength itself.

You are better off rebatching sooner so that you will need less heat over less time to melt down the soap to the point that you can add more scent, mix, and repour into the mold. IMO, the fragrance will be more negatively impacted by a longer rebatch time (I.e., more exposure to heat), as opposed to rebatching before full saponification (since the latter really doesn’t relate to the fragrance’s “sticking-ness” if you will).

 

[lsg]

Here is a way to add milk to your rebatched soap without it turning brown. Just be sure that you are using "instant powdered milk." If not dissolve the milk powder in hot water before adding.
https://pvsoap.com/re-batch-or-hand-milled-soap/

 

[Peachy Clean Soap]

Great answers from Todd and Dibbles regarding FOs sticking.

I have rebatched a LOT of soap in the past, and occasionally still do. I do add additional fragrance to my rebatches to compensate for the loss of scent strength when reheating the soap.

I also used to HP a lot, which is basically similar to rebatching, except that all scent is added at the end of the cook (instead of just the additional scent).

In both situations - rebatch and HP - the scent usually sticks more than it does in CP. But if a scent fades in CP, it will eventually fade in HP or rebatch, too.

Some people have good success with using clay to anchor their scents, while others don’t see a difference. Lots of good threads here will explain that if you want to search and read about that.

Regarding milk soaps (and other soaps with sugar content), rebatching has never caused mine to darken, probably bc the sugars have already “cooked” during the saponification process. That’s my personal guess and not a scientific explanation as to why no darkening occurred.

I saved your second question for last. You don’t need to wait for complete saponification to rebatch. It will be easier in fact if you don’t. The more water that remains in the soap, the faster the rebatch will go.

Also, while fragrances are somewhat affected by lye and the saponification process, they don’t “saponify” in the way that oils do.

So I think you are conflating two unrelated issues here. Yes, your fragrance will be affected (weakened somewhat) by the additional heat from rebatching. But I don’t personally think that timing the rebatch to occur after full saponification will affect the scent strength itself.

You are better off rebatching sooner so that you will need less heat over less time to melt down the soap to the point that you can add more scent, mix, and repour into the mold. IMO, the fragrance will be more negatively impacted by a longer rebatch time (I.e., more exposure to heat), as opposed to rebatching before full saponification (since the latter really doesn’t relate to the fragrance’s “sticking-ness” if you will).

Wonderful explanation on rebatch' I was gonna add my 2 cents worth but not needed, you covered all the basses.

 

[CatahoulaBubble]

I've rebatched way too much soap lately. The fragrance does stick more if you add the fragrance right at the end before you pour it. I can't comment on discoloration because most of my rebatches are because I made a mistake or had soap on a stick so when I cooked it in my pot it all became gray. I've been able to save some of it by either going black or adding blue to it to make it more of a blue gray. The one time I did a hot process soap on purpose it was a milk soap and there was no real discoloration, it was just a creamy beige color.

 

[allybee]

Wow, thanks for all the great replies, I really appreciate it!

So the take aways I'm getting from this is:

- Rebatch soap does hold fragrance somewhat better than cp soap but the quality of the fragrance oil is all-in-all a much larger factor in scent retention.

- Soap should be rebatched as soon as possible after solidifying and passing the zap-test to reduce heating time, which has also has a negative effect on fragrance.

- Rebatching milk soap does not typically cause discoloration but adding powdered milk during the rebatch can avoid the issue alltogether (wouldn't really apply to me since I'm using plant milk and there aren't that many plant milk powders available).


Yeah, I guess I've been a little stingy with my fragrances...so far I've only used purchased from Nature's Garden since their 1 oz trial bottles are pretty affordable and consistent in price. I'm an unemployed high school senior paying for all supplies out of my own pocket so I'm just desperately trying to make this a sustainable hobby. I also wonder if I'm just expecting a bit too much out my fragrances; I'll get my hopes up from the smell directly out of the bottle and am then disappointed when the soap doesn't have the exact out-of-bottle scent. It might just be that the scent from the bottle will never fully translate to the finished soap. Guess I'll just have to experiment some more to find out.

 

[Zany_in_CO]

Well this got me wondering: does rebatch soap also hold bright fragrances better?

Good thinking!

1. In your experience, does rebatch soap hold fragrances better, specifically light/bright fragrances with strong top notes?

IME, Yes. I add fragrance to the warmed oils before adding the lye solution.
Hmm. "top notes" are not strong and tend to fade as the Mid and Base notes take over.

2. What's the minimum amount of time I should wait before rebatching to ensure that saponification is 100% complete and that the fragrance won't be impacted?

I rebatch as soon as the soap can be grated easily but not so soft that it gums up the grater. I once needed to get a soap shipped by the end of the week. I made the soap. Grated it the next day. Rebatched the next day and repeated the process one more time, adding fragrance at the end.

3. If I rebatch milk soap, will the heat discolor it?

In my experience, yes. If you soap cool to prevent gel then you have a nice creamy white soap. Rebatching is like "forcing a second gel". Gelled milk soap is most likely to be a shade of tan.

ETA: PRETTY IN PINK (oven rebatch with pics). Used WSP's "Pink" EO/FO Blend. Bright floral fragrance similar to Carnations I think. The rebatched bars are still holding their scent. I used WSP's fragrance calc to add the correct amount of fragrance.