Rebatching. This is sometimes a dirty word. What is it and why do people do it?
Rebatching is sometimes confused with milling, or French milling. Rebatching is when a batch of soap is melted and additional items are added or a failed batch is reworked. Rebatching is done to make small, custom batches of soap from a large initial batch. The resulting bar of soap has a shorter shelf life than a properly prepared, handmade batch of soap. Rebatching is also a soap that is more likely to be cosmetically challenged (ugly).
Milling is when excess lye, fat and glycerin are removed from the soap and the resulting soap is shredded into flakes, pressed through a series of rollers and then molded. Milling makes a hard bar of soap that can last a long time. It is also not as skin friendly as a properly prepared, handmade batch of soap. Milled soaps are generally beautifully molded bars. These soaps are also more likely to be brittle.
Rebatching, when done to save a batch, is the only time MMS recommends doing this labor intensive work. Our favorite method of rebatching is the oven method. While still time consuming, the oven method is not a constant attention process.
To rebatch, using the oven method we use, shred or grate all of the soap and put it in an oven proof, lye resistant container (glass or stainless steel please!). Set the oven to 200 degrees F. Pour a bit of boiling water over the soap gratings and mash with a potato masher. I allow 1/2 hour for each pound of fat in the original batch. I mash and stir each 1/2 hour until the mixture appears fully melted and smooth in consistency. The mixture will probably be thick but it shouldn’t have major chunks. Small bits are OK to leave, but do expect color differences in the final bar of soap if you leave any small bits unmelted.
Add boiling water anytime you get a mixture that is too thick or dry. Do not add a lot of boiling water, just a little. If too much boiling water is added, then the soap will expand and probably float. Very wet soap is a problem because as it dries the sides will become concave.
To avoid the work of rebatching, try making each batch correctly the first time. The idea of making a very large batch of soap, then intentionally rebatching 1 lb at a time, seems to be wasteful of life’s precious minutes. No bar of soap that has been rebatched is an improvement over a properly made batch of handmade soap. Rebatching is for prevention of ingredient loss. It is a “waste not, want not” activity.
how dose rebatching shorten the shelve life? very curious here as i have done both cp soap and cp base batches and tend to stick with rebatching for the simple fact that it dose not take as much EO’s to scent as the first go round dose. Times like these i try to find find ways to strech what we have in our budget for scenting our soaps and still mantain our high quality of herbal and EO packed soaps. We like to add a super fatting punch at our rebatching phase as well with added shea and cocoa butters to double the moisturizing quality of our products as well. Any ideas out there ???? Or any known problems with this process????
dustie & sincerlyemily,
The extra oil will oxidize sooner. The additional heat, the extra water introduced and the extra oil all combine to have a product which has been more exposed to air and detrimental conditions. This will cause the superfatting oils to go rancid. Plain cold process soap, when kept cool and dry, can last 2 plus years without a problem. Soap with extra fats added, rebatched, or extra water which was added during a remake processing, all cause the bar to be more prone to rancidity.
My question is the same as Dustie’s. How is the shelf life shortened and what shortens it? Thanks, Emily
Just wanted to mention — some soapers actually prefer to add their “goodies” at rebatch. Here’s what I do.
1) Make soap using full water amount.
2) Grate up or chunk the next day. Put in large stainless steel pot. Cover.
3) Put in 250° oven for 1 hour. NO LIQUID added. No “mashing” necessary. No guessing on how long to cook.
4) Soap should be molten after an hour. If not, repeat for 20 minute increments. Stir. Add goodies. Stir again.
5) Mold up; unmold and cut when fairly firm; set out to cure.
I’ve done this once, then again the next day — 2 days in a row, adding my goodies after the second melt. Not only works well, but cures more quickly too because some of the excess water evaporates during the process.
Rule of thumb: No liquid necessary for fresh soap; for fairly young soap, add just enough liquid to wet all the gratings; for old soap, you can add up to 1/3 the weight of soap.
NOTE: You can also add enough liquid to cover the gratings. This results in a wetter soap, takes longer to cure, but you get a smoother finish — unlike the marbled effect one normally gets from rebatching.
Use water for lard & tallow soaps; milk (any kind will do, but coconut is nice!) for all vegie soaps.
thaks Zany, i will try a base batch tomorrow and add my super fatting mix at trace, then i will shred the next day and leave out the liquid i will add my EO’s and herbs the second day so the lye dose not eat up the majority of my goodies 🙂 sounds like a good way to avoid the problems of them going bad. Andee what is your opinon on thi process?? like i said before we are trying to keep high quality soaps but stay in our tight budget. our small business we have started we are funding all o our own. This can be tricky at times 🙂
Andee, I have one more question please i hope you have the answer. I love lemon EO as well as Tangerien EO but it never sticks in my soaps or my salts…. ???? why and how can i make it last??? i have tryed powdered benzoein as well as tryed orris root powder no luck with either….. do i need to increase the amount of these ingrdeients or is there another natural fixitive that will work better??? our business is built on being very green and earth body friendly so the only snythetics we use are fragrence oils. even our colors are done by herbs and spices. it can be very chalenging but worth it to us. Can you help PLEASE…. Thank you so much!!!
Rebatching, whether water is added or not, will cause the soap to oxidize sooner. Certainly some people prefer this method. This is much a preference thing with cars, meals and books. If your goal is to make a soap and use less essential oil, then rebatching may help. If your goal is to make a large batch then remake only what you want at a time, then rebatching is certainly for you. If you want a soap that will last on the shelf for 2 plus years, then rebatching is not for you. Consider the overall objective as being the critical point of decision.
As far as citrus oils and staying power, you will need to use more and you can add an oil like castor, almond or other to salts. In soap you will just need to increase the amount you use. Try blending with citrusy smelling herbs like lemongrass and citronella. This will help anchor the scent for a longer lasting odor.
I have a wonderful time rebatching. I do it because it’s fun as well as I love the results. I grate the soap with my kitchen aid mixer. I only take about 4 bars to grade. Into a glass bowl. I use powdered goats milk (1-1 1/2 scoops) and mix it with hot water( 1/3 cup or more). (If I were to add clay I would put it into the milk mixture). I put this into my soap that’s graded and put into the microwave on power level 4 for 1-2 minute intervals with a tea towel or lid, and keep stirring. I do this till it is real nice & soft almost like real soft mashed potatoes. I then take it out & add my frag, or essential oils or what ever else I may want to add After it cools down. Check your flash point on your oils so you get the soap batter cool enough I sometime may add Rose absolute, Or Sea buckthorn, Carrot extract, meadow foam oil etc. I added Rose clay with my milk. It makes a silky bar of soap that people tell me it takes away their dry skin the first time they use it. So I feel it’s because the lye doesn’t interfere with these precious oil’s and the goats milk. I am 62 yrs. old and I want to keep my skin soft & nice. I do not know how long these will keep. But I am sure they will be used before they go bad. Once you try this you may be like me and want to rebatch for the simple reason to make your bars unique. My original soaps are supperfatted at least 8%. I love the soap this way. It still lathers nice too.
I just got my first order and I’m going to do Mango Lip Solution lip balms. A free sample came in the mail with it and it looks like the cold process soap. Is it a soap? ready to use? Reason why I’m asking is that when I ordered the lip solution jar, I didn’t think to order a color to add to it and for a moment, I thought this free sample could be melted and added to the lip balm solution. No? The free sample does not smell like “soap”, it feels waxy like crayons so I just thought …. Anyway, help.
What color is the soap? Was there a label on the bag the sample came in?
The label states: “This FREE sample is from our blog project on July 14th, 2009. Check it out! Searching for a Red Color”.
The soap is orange and has ridges on two sides.
This is a Cold Process Soap using the Ruby Lip Balm Color. The details regarding the soap are on the July 14th post. The title of the post is the bottom line.
I just re-batched my first batch of soap and have a question about it. How much longer is the drying time and does rebatching hurt the integrity of the soap.? Does it last as long as a regular bar of cp soap that has not been rebatched?
Generally it takes a few more weeks 4-8 to dry out. I don’t think the soap shelf life is as long but I don’t have a scientific study to prove my theory. I would use up the rebatch in 1 year and the cold process soap in 2 to 3 years.
After reading this, I tried a rebatch yesterday. I first soaked the grated soap in a small amt of water. After 3 hours I put it in the crockpot on low, turning it off when it got too hot. After about 3 more hours I put it in a lined loaf mold. This morning It is still liquidy, how long before it starts getting firm??
It sounds like you added too much water. It will take several weeks to dry out. I am sorry.
Ok, so in order to fix this, can I put it back in the crockpot with some more grated up soap to account for the water?
Hannah, Are you chasing good soap after bad? We only advise rebatching if the soap is a problem and will otherwise be discarded. If you are trying to save bad soap, just change it to something else like laundry soap.
I have a question… how does milk not spoil in a rebatch soap like it would in melt and pour soap? since the soap has already gone through saponification what keeps the milk from going bad in a rebatch CP soap?
Milk can turn in a batch of soap but low levels of water in the finished soap will keep the oxidation odor at bay.
Soaps which have milk added at rebatch or at the melt and pour stage can easily turn off. The key is adding at a small percentage and allowing the water to evaporate quickly. If we can get the water out of the milk far less problems will arise in the decomposition process.