liquid soap ...from scratch

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you would think that once you become comfortable with making soap from scratch, it would be an easy segue to making liquid soap. au contraire! as covered in "[bar] soap from scratch", cp (cold process) soapmaking is easy, (which accounts for it's popularity), as compared to hp (hot process) soapmaking. it's not so much that hp is more difficult, just more involved. plus, the "hot process" or "cooking" makes the soap itself harder to work with. although liquid soap falls into two categories: "bar-soap conversion" and "hot process", the latter is the most involved and is necessary to produce a viscous, transparent, clear liquid soap.
i first went the easy route, reviewing recipes for a simple way of converting solid soap to liquid form. although the procedures varied, all the recipes basically came down to grating bar soap and diluting it with water. if this dilution is too thin, it's not effective a soap doesn't lather [well]. if it's too thick, it wants to congeal into an "unusable" glob of slimy goo. although I came out with a usable product by following this recipe for "bar-soap conversion", this was not what i wanted.

click to enlarge
since the results of converting bar soap to a liquid proved unsatisfactory, i decided to tackle the hot process method for making a transparent liquid soap from scratch. the first step was to get [one of] catherine failor's books* entitled "making natural liquid soap". i did, and as i read, i realized that this was a bit more involved. but just as i overcame my initial apprehension of cp soapmaking, i was sure i could conquer this. after perusing the manual several times and sifting through all the facts and details, i proceeded with the method outlined below.
(*subsequently, i obtained ms. failor's other soapmaking publications entitled "making cream soap" and "making transparent soap". i've chronicled my exploits working with these fascinating and very-different soaps on my "cream soap" and "transparent soap" pages.). and lastly, there's "whipped soap", which i've added to round out the soapmaking repertoire.

this is the method i used for the hot process liquid soap: -- (see "soap recipes" for my liquid soap recipes)
decide the batch size and determine what oils are being used. the table of "oil properties" lists the oils and their component fatty acids. unlike cp, your aim here is not to use too much of the soft oils since this will cloud you final product. this is not a consideration is you don't care about transparency.
as with cp, i've decided to work in small 1-lb. batch sizes. when the "paste" is diuluted in a 30% solution, this will produce approximately 1 quart (32 oz.) of liquid soap.
[i read somewhere that] it's a good rule of thumb to use 1 part hard oils and 2 part soft oils. this sounds like a good starting point so the oils being used are 1 part each of olive oil, castor oil, and coconut oil. i intend to superfat with sulfonated "turkey red" castor oil, which is added to the finished soap (at the rate of 2% of the diluted soap).
another factor in selecting your oils will be the color and odor a particular oil imparts to the final product.
using your favorite "lye calculator", determine and measure out the amount of lye needed. cover container and set aside.
i used a 10% lye increase, (the opposite of a discount), per suggestion from the book "making natural liquid soap".
this higher amount of potassium hydroxide, (according to ms. failor), is to insure that all the fatty acids are saponified and thus produce a totally clear transparent soap. the resulting soap is then neutralized. this does seem to be a sure-fire method to insure that all the oils' fatty acids have been saponified.
there are those who feel that deliberately making the soap alkaline and then neutralizing it reduces its efficacy. however, having tried both approaches, i don't support this conclusion.

note: when using an oil like jojoba, which contain substances that do not saponify, there will always be some unsaponified material regardless of the lye amount. this will "cloud" the final product in direct proportion to the amount of the oil used.
determine and measure out the amount of water. this does not have to be chilled.
the water amount is 3 times the total weight of potassium hydroxide.
if a goat's milk soap is desired and the milk is being added during the process, deduct the amount of water used to reconstitute the powder or [approximately] 85% of the amount of whole milk ...see the "goat's milk page".
mix in the lye, pouring slowly and stirring constantly until all the lye is dissolved.
as with sodium hydroxide, do this outdoors or with plenty of ventilation, being careful not to inhale the fumes and dust from the lye. lye is caustic. never use aluminum utensils since the lye reacts with it ...use high density plastic or glass. wooden spoons are also not appropriate since the lye eventually corrodes and splinters the wood.
as with cp, add the lye to the water (not the other way around) and stir to dissolve completely. this solution will not get as hot as that used in cp; it will reach a temp of around 150°f. let this cool slightly. you'll want the lye/water to be approximately 140°f to be mixed with the hot oils (160°f).
fill the bottom half of a double boiler with water, bring to a boil, lower the heat and let simmer (just below boiling) so it'll be ready when needed a few steps.
all the instructions i've read use the term "double boiler", but what is actually called for is a bain-marie. the difference? with a double boiler (image to the right), the upper pot sits within and atop the second, and the bottom [of the top pot] may not even touch the boiling water.
with a bain-marie (image to the left), the top pot is immersed inside the bottom pot so that, (in this instance), the water level is equal to the level of the soap within. this is to assure that the soap is being thoroughly heated.
also, if the bottom pot has a lid and is large enough to completely contain the soap pot, this will conserve the heat and reduce the steam created by the long cooking process.
to confuse matters even more, a double boiler is often referred to as a bain-marie and a bain-marie as a double boiler. go figure.

an alternative to the "bain-marie" is the oven. if your [covered] soap pot will fit, you can cook the soap in a 250°f oven for the alloted time. this doesn't lessen the cooking time, but you won't have to deal with constantly replacing the evaporating water, the room won't fill with heat and steam, and the temperature all around the pot will be constant. you will have to periodically stir down the soap since it wants to "soufflé" when it gets hot ...especially if you've added goat's milk, (which increases the processing temperature).

heat your oils to the desired temperature.
you'll want to have your oils around 160°f as your lye/water cools to around 140°f.
as with cp, there are some recipes that quote different temperatures and also require the oils and lye/water to be at the same temperature. i'm going with the recommendations from "the book" (160/140).
in a steady stream, add your lye/water to the oils ...stirring slowly (in a figure-8 motion). once all the lye is incorporated, alternate between stirring with a [plastic or stainless steel] spoon and using a stick blender until mixture reaches light trace.
"trace" is different for liquid soap. the mixture will stay thin for a much longer time and then suddenly turn thick. even then, you're not finished. continue to stir until the mixture is stiff like a very thick custard or taffy.
if making goat's milk soap, add the milk half-way through this step, after the mixture starts to show signs of thickening. by adding the goat's milk here, enough lye has been consumed so as not to adversely affect the milk proteins but it's still early enough in the process to "absorb" all the milk solids. you will still produce a transparent soap ...although it will be amber-colored ..see "using goat's milk in liquid soap".
during this time, try to maintain a temperature around 160°f. too much over and your soap will bubble over; too much under and it'll take forever to trace ...even with the stick blender.
there are ways to facilitate trace. one is to mix lye/water with oils, stir for 10 minutes, and then let sit insulated overnight, during which small droplets of soap are formed. the following morning heat the mixture to between 160°f and 170°f and stir until trace. this will tremendously decrease the stirring time.
another way is to incorporate a small amount of undiluted soap paste from a previous batch. dissolve this "starter" into the oil and lye mixture and then stir to trace.
adding a small amount of alcohol is yet another method used to shorten the stirring time.

cook the soap.
bring the water in the bain-marie (bottom of the double boiler) to a gentle boil. put you soap pot in the boiling water. if [the bain-marie] has a lid, use it. -- or place the [covered] soap pot in the oven.
cook the soap for 4 to 5 hours, stirring every 20 minutes at the beginning and less often as the time expires. if using the bain-marie, replenish the [boiling] water as needed so that it maintains a level equal to the level of the soap.
during the beginning of this phase, the soap may "puff up" and expand. the "book" says this is trapped air and can be collapsed like you would a soufflé. i disagree. from experience, i've found this puffing up is due to excess heat. most often just stirring the soap down will collapse it. in extreme cases, just remove the soap pot from the bain-marie (or oven) and let the soap cool as you stirred it down ...and then return it to the bain-marie.
also during this time, the soap will change in appearance from milky off-white opaque to translucent.
check soap for excess fatty acids.
after 4 hours, test to see if the soap is thoroughly cooked and that there are no un-neutralized fatty acids (unsaponified oils). take a small amount of soap paste and dissolve it in double that amount of boiling distilled water. this will be clear when hot. let it cool. if it turns cloudy, then the soap needs more cooking. repeat the test as necessary every 30 minutes. when the soap is finished cooking, remove the soap pot from the boiling water.
"the book" suggest a cooking time of 3 hours, but this quite often is not enough. by planning on a cooking time of 4 to 5 hours, this insures the soap will be thoroughly cooked.
note: if you've added goat's milk, the cooled dilution test will still cloud, making it difficult to determine when cooking is complete. as a result, i simply cook for the full 5 hours.

10 package and store the soap paste -- if the objective is to convert all the soap paste to liquid form, skip this step.
when the soap has cooled, chop up the [hardened] paste and place it in a jar or plastic bag. seal and place in the refrigerator where it can be stored indefinitely. you can remove just the amount you want to dilute into liquid form. a small amount (read one ounce) of this paste can also be used as the "starter" for your next batch.
11 dilute the soap.
take the soap paste to be diluted and put it into a pot with boiling distilled water. the amount of water will determine the concentration. the higher the [soap] concentration, the more reluctant the paste will be to dissolve.
a no-hassle way of dissolving the paste is to bring the water to a boil; put in the paste, breaking it up into small chunks; cover and let sit overnight. a 25% concentration will dissolve in about 8 - 10 hours; 30%, about 16 - 18 hours; higher concentrations take proportionately longer.
12 determining the concentration.
the concentration of the soap is not just a matter of choice. it's also determined by the oils you used. a concentration that's too low produces a soap that won't lather effectively, too high and the soap will congeal back into a paste.
soap from softer oils can only withstand so much concentration before it starts to congeal; sometimes as little as 20%. soap from all hard oils (e.g. coconut) can take a concentration of up to 40%. soap made from a mixture of hard and soft oils takes a concentration from 25% to 35%.
among other things, borax is an emulsifier and adding it to your soap will allow the soap to sustain a [higher] concentration where it would otherwise start to congeal. i'm going for a concentration of 30%.

use the table to the left or calculate for yourself; the formula for determining dilution is simple. find out the percentage of actual soap in your paste (divide weight of (lye and oils) by the weight of the paste. this will be around 64% - 66%. now multiply the weight of the paste by that percentage. this is the weight of the actual soap in the paste. now, divide that amount by the desired concentration, (say 30%). this is the projected weight of your dilution. finally, subtract the weight of the paste from this projected dilution weight. the result is the amount of water you need to add to the paste to achieve the selected concentration.
for 100 gm pf paste with a 65% of actual soap, diluted for a 30% concentration, the numbers are as follows: (100 times .65 = 65; divided by .30 = 216.6; minus 100 = 116.6 gm water needed).
water per
lb. of paste
15 percent48 ounces
20 percent32 ounces
25 percent22 ounces
30 percent16 ounces
35 percent12 ounces
40 percent9 ounces

if you're making goat's milk soap, and are not concerned about transparency, you can add [reconstituted] powdered or whole goat's milk by substituting it for all or part of the diluting water. (this could be in addition to the goat's milk added during the initial soapmaking process, but generally you would go with one "or" the other.) see "using goat's milk in liquid soap". because of the addition of the milk, you may opt to add a preservative (e.g. suttocide).
13 sequestering, neutralizing, thickening, preserving, and superfatting.
this is where "the book" comes in handy, as a reference source. it covers many different scenarios and suggests what and how much to add to address a particular concern or to impart a certain quality to your soap.
without recounting all the whys and wherefores, i'll just summarize. i don't "sequester", since i'm satisfied with the clarity of my soap upon dilution.
i "neutralize" with a 33% borax solution (2 - 3 tbs./lb. diluted soap). my neutralized soap has a ph of 9.5 - 10. since my soap formula is high in soft oils, the borax also doubles as a "thickening" agent. -- click to see notes on [thickening liquid soap]
i usually don't "preserve", but if i were to use a preservative, i would incorporate 1% suttocide. (see "preservatives" regarding possible reaction of suttocide with your fragrance.)
i "superfat" with 2% sulfonated castor oil, which also doubles as an emulsifier and aids in minimizing the clouding effect of certain essential / fragrance oils.
14 add fragrance, [optional] color, and bottle.
add a little fragrance (1% to 2%), bottle (use a clear container to display the clarity of the soap), and voila!
if you desire color ...other than that derived from the oils used ...add a few drops of water-soluble food coloring.
in the [left] example, no additional coloring was added.
15 variation sans transparency.
if transparency is not an issue, you're not restricted to certain amounts of certain oils/fats. you can use a higher percentage of butters and waxes, and you can incorporate a low level of superfatting (2% - 4%) ...not too much since this would negative impact the soap's lather. were you to incorporate a superfat, you're not over alkalizing, so you won't need to neutralize.
16 notes on borax.
many people, as well as some suppliers, (who should know better), use the term "borax" and "boric acid" synonymously. this is grossly incorrect.
borax is "sodium borate", a crystalline mineral salt mined from the earth. (available at your grocers as "20 mule-team borax".)
"boric acid", (a highly diluted form of which is commonly used as an antiseptic eyewash), is a compound, mainly [commercially] produced from the steam and vapors of the volcanic region of tuscany. it can also be produced by treating sodium borate with sulphuric acid. they are not interchangeable so don't confuse one with the other.
view the "thickening liquid soap" page to see how beneficial borax is in producing a clear transparent thick liquid soap.