Category Archives: How-To

How To: Rebatching

Rebatching, also known as milling, is a process by which existing soap can be shredded, melted down, and turned into fun new soaps. There are several applications for this technique. One is for soapmakers to salvage a batch that’s not gone quite right; it affords the opportunity to tweak proportions of things a little and try to bring a soap back into the fold when it’s gone a bit wrong. Another is the ability to incorporate scents or embedded items which are too delicate to withstand the harsh alkaline environment of raw soap.

Perhaps the best advantage of rebatching, though, is that it allows a remarkable degree of customization, and affords those who would prefer not to work with lye the ability to exercise their creativity in the realm of soap. Rebatching is fun, easy, quick, and at its simplest requires no tools or ingredients not found in the average kitchen, with the exception of the soap itself.

Any bar soap can technically be reworked and reformed in this fashion, but handmade cold- or hot-process soap works best, and the younger (less-cured) the better. Once you have obtained the soap you wish to use, you’ll want to shred it (or buy our pre-shredded rebatching base) to reduce the amount of time it will take to melt, and also help ensure even melting. For the sorts of quantities we’re dealing with here, this can be done quickly and easily with a regular box grater.

Shredded soap.

How much soap you start with depends on how much you want to make! This tutorial is structured around the idea of making a single bar, so it starts with about four ounces of soap, which is then placed in a quart size freezer bag (freezer bags are best for this method because they’re made of sturdier plastic than regular storage bags, and it’s going to get hot later).

In the bag.

Add a tablespoon or so of water or other liquid. This is one area in which you can be creative – use milk, chamomile tea, beer, whatever you like! The amount of liquid needed will vary based on how cured (dry) the soap you start with is, so you may need to tinker with it a bit. Err on the side of less liquid rather than more, though; you can always add more later and then repeat the next few steps, but once you’ve added too much your only options are adding more shredded soap to the mix or ending up having to wait for WEEKS for your soap to be ready to use when you’re done. If you’d wanted to wait that long you could have made soap from scratch instead!

Press out as much air as you can from the top of the bag, seal it, and gently work the soap inside the bag such that the liquid you added is distributed over all the soap. Don’t get too vigorous about it, though; any suds you work up in the soap in there now will almost certainly still be in your finished soap and make it feel spongy. (Note: Creating this effect on purpose is one way to end up with Floating Soap!)

Now it’s time to bring on the heat! There are multiple schools of thought on this, but over time I’ve come around to the oven method. I simply set the oven on “warm”, place the bag o’ soap on a pan or dish to keep it from direct contact with the oven rack (if your oven runs hot, you can fill the dish half-full with water before adding the bag of soap as an extra protection against melting the plastic), and into the oven it goes, for . . . well, for as long as it takes. Sometimes it takes a couple of hours…

My soap at two hours.

…but this time, not so much. Back into the oven for another hour!

All melted!

This soap was a bit drier/older than is really ideal for rebatching with, so it took a bit longer than it might have otherwise, but one thing is just as true about rebatching as it is about all other things in soaping: You can’t rush it! It’ll be ready for the next step when it’s ready, and not before. So keep checking your soap, and when it’s all translucent and sort of gloopy (about the consistency of oatmeal), then it’s ready to go. If it is persistently failing to reach that point, you may need to add a bit more liquid. Don’t be afraid to experiment a little. After all, it’s just soap, and there’s not much you can do that will ruin it completely. Be careful, though, it’s hot!

Right. Now that the soap is all gloopy and gloppy, it’s ready for the next step. (If you don’t want to add fragrance and/or color, you can skip either or both of the next two steps and go straight to the into-the-mold stage.)

Adding fragrance.

It’s time to add the smell-good stuff! Any skin-safe fragrance can be used here (don’t use potpourri fragrances, diffuser oils, or most candle fragrances). Most people don’t have a soap supply store in their hometown (not that I do, either, more’s the pity), so the easiest place to find scents you can use for this may be the essential oils counter at a health food store. Some of these are very expensive, but if you look a bit, you shouldn’t need to break the bank to be able to find something you’d be willing to smell like after a shower.

I add fragrance in small amounts with a pipette, visible in the photo above. Most people don’t have those, so I’ll translate to other terms. My default fragrance percentage for soap is about 1%, which means this 4 oz batch got about 0.05 oz of scent. If you have a sensitive kitchen scale and a delicate hand with the pouring, you can stop there and use that measurement, but if you’d rather not risk a momentary hand-twitch upending the entire bottle of fragrance into your hapless soap batch, we can translate it into volumes, and you can use a quarter-teaspoon. It’s an approximation, but for these purposes it will do. This amount is only a starting recommendation, of course – this is your soap, it should smell like you want. Use more, use less, use however much you like! Once you have added the scent, close the bag back up tight. Either wearing heat-proof gloves or after wrapping the bag in a towel, squeeze and squish the bag until the fragrance is thoroughly mixed in to the soap. If it cools off and starts to set up around the edges, toss it back into the oven for a bit to re-melt.

I also added some color to this batch, in the form of LabColors, which are a bit on the pricy side for tinkering/hobby purposes. You can use food coloring if you like; just experiment and see what sort of results you get. Or, when you go to the health food store to get the essential oils, take a look in their bulk section and see if they have any dried flowers or other fun things you might want to mix into or sprinkle onto your soap for some visual appeal. Lavender buds, calendula petals, lemongrass – there are all sorts of possibilities!  If you’re mixing in color, you can do it at the same time as you’re mixing the fragrance, but I like to do it separately afterward – it’s hard to see the fragrance to be sure it’s all mixed in, and if you think it’s all mixed in, then add color and mix that until you can see it definitely is all mixed in, then you can be pretty confident in assuming the fragrance is completely and totally mixed by that point. If you’re using flowers as mix-ins, add them at this point, too. And don’t forget the gloves/towel, because the soap is still hot!

All mixed up (and with some spilled colorant next to it, too).

OK, once you’ve got everything all mixed in, it’s time to put it in the mold. What’s that? You don’t have a mold? Well, neither did I the first dozen or so times I did this. I’ve used washed-out yogurt cups, muffin tins (with liners), ramekins, and just about anything else I could find in the kitchen that was more or less the right size.  If you happen to have one of those silicone individual-brownie pans, those are just about perfect. Things that are flexible are best, because it’s easier to get the soap out of them afterward – and if you do happen to want to use a meant-for-soap mold, try to pick one without large amounts of detail. Rebatched soap is not liquid when it goes into the mold, like melt-and-pour or original cold process, so it doesn’t take up detail well, and indeed can get hung up on the little finicky bits of the mold and tear when you try to take it back out.

This being just a single-bar batch, you can get it out of the bag the easy way: Cut off a corner of the bag and squish it out into the mold you’ve chosen, then lay the bag down over the surface of the mold and use it to help you smooth the top of the soap flattish – but take it back off pretty quickly, before the soap tries to set onto it. If you’re adding flowers/etc. to the top, add them now and press them in gently so they will bind to the soap.

In the mold.

See how it doesn’t fill the mold quite to the corners, even though it’s a simple square? I could have squished it a bit more tightly into the mold, but I’ve learned to embrace the rustic and organically-shaped nature of rebatch – and, in fact, I let this one keep some unmelted bits of soap specifically because I wanted the speckled look they produce in a colored milled soap.

The next day.

And voila, a bar of soap. It was ready to unmold the day after I made it, which is not necessarily usual; sometimes they need a few days if you use more liquid or the soap was newer or any number of other variables. But it’s pretty much ready to use as soon as you finish it, though if you leave it to dry a while longer it will probably last better once you start using it, and if it still feels soft to the touch it definitely should stay on a shelf a while.

And there you have it! Rebatching is fun and easy, and if you find you like it, you might just end up giving everyone you know gifts that you made yourself!


Many people prefer to put the freezer bag into a pot of boiling water rather than into the oven. This has the advantage of being a constant and known temperature, whereas the oven can fluctuate, but I’m not fond of steaming up the kitchen and having to keep topping up the boiling pot. It does certainly work, though, if you’d rather do things this way.

If you get the rebatching bug in earnest and want to make batches larger than can readily be done in even a series of freezer bags, there are several methods for doing that as well. Melting the soap in a double boiler, in a crockpot on low or warm, or in a bowl in the oven at low temperatures are the main contenders. Try them all and see what works for you!

How-to: Lotion

When I was learning to make soap, it was not a smooth road; not every experiment worked perfectly. Still, I have only once ever ended up with a COMPLETE disaster of a result when making soap, which was not due to a failed experiment, just evidently One Of Those Things (seriously, I never have figured out what went wrong with that batch).

On the other hand, when I was learning to make lotion, I had failure after failure after failure. I ended up with oily, slimy messes, with curdled piles of glop, with things gone awfully wrong in about as many ways as things can go. I had books and blogs aplenty telling me ways to make lotion, and I couldn’t make a single one of them work, and it was frustrating.

To help out people who may be having similar troubles, I provide here one of the first successful lotion recipes I ever came up with, which in fact is the direct ancestor of the recipe I still use today.

You will need:

  • Kitchen scale capable of measuring to 0.1 oz
  • Two microwave-safe containers, each large enough to hold the entire batch
  • Spoon, whisk, and/or stick blender
  • Sanitizing solution
  • Thermometer (infrared is best; if using candy thermometers you’ll want two)
  • Containers, NEW AND UNUSED, six 4 oz bottles or equivalent
  • 18 oz Filtered water
  • 3.8 oz Sunflower oil (or other oil(s) of choice)
  • 1.2 oz Emulsifying wax
  • 1 oz Stearic acid
  • Preservative (0.2 oz of Germaben II or 0.1 oz of Liquid Germall Plus)
  • 0.3 oz Fragrance, if desired

Before we get into details, let’s talk a little about the ingredients and why we use them.

Water makes up most of this recipe, because this is a lotion and that’s the way they work. If the proportion of water were lower, it would be a cream – but really, if you lowered the water proportion enough for it to be less than the other ingredients, it would be such a thick cream it would be difficult to use. The water is not only here to help achieve the desired consistency, though – it plays a role in the moisturizing effect of the finished product, too. Using filtered water helps keep out unwanted mineral contamination from hard water, and also bacterial contamination – more on that in a minute.

The oil phase is where you have the most opportunity to play here. I specified sunflower oil because that’s what I started with, but feel free to mix and match all you like – find oils that have properties you like and use amounts of those adding up to the stated amount of oil here, and it should work just fine.

As I’ve mentioned before, oil and water need something to hold them together if they’re not going to separate shortly after you stop stirring. Emulsifying wax is not the only choice for this, but it’s easy to use, fairly inexpensive from just about any soap/lotion/cosmetics supplier I’ve found, and works well. I use another emulsifier for conditioners and facial moisturizers, but more on that later.

Stearic acid (a fatty acid, not an acid-acid) is added here to make the lotion thicker. It’s not absolutely necessary, but does add a nice touch.

Preservative is absolutely vital unless you are planning to a) keep your lotion in the fridge, b) use it up within a couple of weeks, and c) never EVER use it on broken skin, like after you shave or if you have a hangnail. Oil + water = absolutely perfect territory for bacterial and fungal growth, and there’s nothing quite like opening your jar of lotion to discover it covered in a forest of mold. Ugh. The procedure below outlines how to minimize the amount of bacteria in your lotion at the outset, but pretty much nothing is ever entirely sterile, and even if you got it 100% sterile at the beginning, as soon as it’s opened and exposed to air there’ll be icky nasties landing on the surface. So use preservative and stop the growth of yuck in its tracks! I have used two different preservatives over time and like them both quite a lot – I started out using Germaben II, which is very effective, can be added to your lotion after it cools below 140F, and I only stopped using it because I was searching for a paraben-free preservative. These days I use Liquid Germall Plus, which also works well but needs the lotion to cool off a bit more (120F) before you add it.

Fragrance isn’t necessary, but can be fun! Make sure what you use is skin-safe (i.e. not intended for candles or oil diffusers or other things and not tested for skin sensitivities); you can find thousands of options out there from various suppliers.

Right! On to the actual making.

…wait. Not quite yet. First you need to sanitize all your equipment. Everything – bowls, spoons, mixer attachments, a funnel if you’re going to use one, whatever it is, if it’s going to touch the lotion or lotion ingredients, into the sanitizer it goes. It’s not so complicated as it sounds, though – just put the things in the sink, fill it with warm water (but not so hot you won’t be able to put your hand in it to get things back out again), and add a quarter cup or so of bleach – more if you have a really huge sink. After half an hour or so, you can remove the items and rinse them with blisteringly hot tap water, which we can consider pre-sanitized for these purposes.  OK, now it’s time to make lotion.

Heat the water in the microwave until it reaches about 180F. Carefully move to an area out of the way and monitor its temperature from time to time while working with the oil phase. If it falls below 160F, put it back in the microwave for a bit. Holding it at this temperature helps assure the proper emulsion, and also helps cut down on any bacteria there might be in the water.

Put the sunflower (or other) oil(s), emulsifying wax, and stearic acid in the other container and heat it in the microwave on short (30 second) bursts until everything is melted. Check the temperature – if it’s above 160F, set it aside to cool; if it’s below, put it back in the microwave for another temperature burst.

When both the oil and water phases are within a couple of degrees of 160F, gently pour the water into the oil (not the other way around – not only does oil not pour as well so you’d be leaving some of your goodies behind in the bowl, you get a much better emulsion pouring water into oil than the other way around) and stir with a spoon until the lotion is well emulsified. Most people recommend using a stick blender at this point to stir it very thoroughly to ensure the lotion is well blended and smooth, but I don’t find it to be necessary. It certainly doesn’t hurt, though, so go right ahead and do so if you like – just be careful not to go too crazy with it, because if you whip too much air into the lotion it’s likely to set up with foam in the top and feel a bit odd.

Keep an eye on the temperature. When it cools to 140F (for Germaben II) or 120F (for Liquid Germall Plus), add preservative and fragrance and stir thoroughly, then bottle, let cool the rest of the way, and enjoy! And once you’ve got the knack of it, go wild – not only vary the oils as mentioned above, but try adding other things – silk, vitamin E, aloe, silicone, squalane, glycerin, goat’s milk, botanical extracts, whatever you like! Also remember, you can change the consistency by changing the amount of water. Tinker away, and make awesome lotion.

Product Development: Massage Oil

I’ve talked a little about my product development process before, and I thought I might take a closer look at it. I picked massage oil as a starting product for this because it’s relatively straightforward; no complicated manufacturing techniques or chemistry, just ingredient selection and blending.

The development process in action.

The first step in any product development is to come up with a detailed list of what qualities the product needs to have. First and foremost, a massage oil needs to reduce the friction to allow the masseur to apply pressure as needed without causing pain or damage to the skin over the muscles, while not reducing it so much as to eliminate the efficacy of the massage. Secondly, it should be a lightweight oil, easily absorbed by the skin but not absorbed so quickly as to need to be frequently reapplied. Thirdly, the effect of the oil on the skin itself should be considered; it should be non-comedogenic, nourishing and gentle to the skin.

Even for a simple and straightforward product, then, we start out with quite a few restrictions! The last one is likely to be the most restrictive, so let’s start by ruling out all the oils likely to cause clogged pores and breakouts. There are several ways to get this information, but for these purposes a chart like this one should do nicely. So, it looks like we’ve got quite a few low-comedogenic oils to choose from. Bringing in the “lightweight” criterion cuts the field a bit further; after all, anhydrous lanolin is luscious in its way, but it is in no way a lightweight oil.

At this point it’s time to start experimenting a bit. It’s no secret that I love to use sunflower oil in pretty much any context I can get away with, so let’s put that in the mix. Avocado oil is lightweight, easily absorbed by the skin, rich in vitamins A, D, and E – absolutely, bring that on, too. Jojoba oil is a fantastic oil for the skin, due to being similar to our skin’s natural oils and easily absorbed, but doesn’t have a lot of “slip” as oils go, so we’ll add a little of this one for the beneficial stuff but not enough to reduce the main function of the product. Castor oil would ordinarily not qualify due to being a very thick oil which might easily make the blend feel too heavy, but it adds great slip and is really fantastic on the skin, so a bit of it in the formulation is probably worth the risk.

And I think that’s enough for an initial formulation. There are plenty of other oils I could have chosen (sweet almond oil, apricot kernel oil, olive oil, safflower oil, sesame oil), and if the initial trial formulation proves problematic in some way which sends me all the way back to the drawing board, I’ll consider swapping some of my choices out. For now, though, we’re starting with:

  • 1.5 oz sunflower oil
  • 1 oz avocado oil
  • 0.5 oz castor oil
  • 0.2 oz jojoba oil

Having blended these together, I can already tell I’ve almost certainly used too much castor oil and am very likely to want to scale that back in future iterations of the development. But for now, I need to finish this batch off so it can be tested, so I have another question to resolve: What shall it smell like? None of the oils I’ve used in this formulation have any overpowering smells of their own to do battle with the fragrances I choose, and I do love to use my test batches as playgrounds for fragrance combinations I haven’t tried before. So today I blended vanilla and rose to create a remarkably sensual effect, which blend I’m now considering putting into wider usage. I had considered using a eucalyptus and mint blend intended to help sore muscles, but I knew what that smelled like and wanted to test this out, so it won instead.

Ready for testing!

And now the product is ready for its first round of tests. But wait! That’s only a 2 oz bottle, and we made 3 oz of test product! Well, the remaining 1 oz is in another bottle, to which I also added 5% cyclomethicone, a silicone “dry oil”. After all, it’s not really Science! unless we have some variables, right? The purpose of the cyclomethicone experiment is twofold: It might increase the slip a bit, and can in some formulations reduce the feeling of greasiness which can be associated with heavy oils. I look forward to determining whether the addition of this small amount of cyclomethicone counteracts the heaviness of the castor oil, or whether I will still need to reduce the proportion of this oil in future formulation refinement.

There you have it – the product development process from drawing board to its first trip to the testers. Sometimes, as today, this process takes about an hour. Sometimes, it takes months – some products fail so obviously for their first few variants that it’s quite a while before they’re ready to be tested properly.

What happens next? After testing, the product is either reformulated and re-tested, or it is sent live and made available for sale.  We’ll see which way this one goes in a week or three.


Sometime in the last couple of weeks, I managed to pull a muscle in my neck, and it complains about it for the first several hours of every day. Fortunately, I’ve been tinkering around with a muscle salve recently, and have the prototype available to apply frequently to keep me moving around and able to get things done!

This is a work in progress; I’m quite certain I’ll change it up some more before the final product goes on sale. But in the mean time, I’ll share the recipe for the version I’m using right now:

  • 2 oz castor oil
  • 0.5 oz shea butter
  • 0.5 oz cocoa butter
  • 0.5 oz beeswax
  • 0.2 oz menthol crystals
  • 0.2 oz eucalyptus essential oil

Melt together the first four ingredients; allow to cool to just above 100 degrees F, stir in menthol crystals and eucalyptus essential oil, pour into jar. It’s very simple, but it helps! (If you add the menthol crystals to the melted salve when it’s still too hot, they will volatilize and most of the goodness will boil off into the air rather than staying in the salve where it belongs. So watch those temperatures – but don’t wait too long, or you’ll be trying to melt crystals into something with the consistency of honey. If you miss the window, try putting the salve into the microwave for very short bursts of time, ~15 seconds or so, to warm it back up enough to stir and pour.)

I’m going to be adding some arnica in future iterations, and very probably more extracts as well, and may tweak the composition of the base salve itself, too. Development is on hold at the moment, though; I’m too busy using the stuff to think too much about changing it!