How to make transparent soap
Making transparent soap from scratch is not very difficult, but patience is definitely needed, as it definitely takes several hours.
You can read in almost all of the “how to make transparent soap” manuals, that to master the technique, it is a big advantage to be familiar with the hot process soapmaking.
Indeed, but I tell you what – I did try to make transparent soap without any hot process experience. Actually, I only made a few batches of a cold processed soap at that time.
So yes, it is possible even without much experience, but you must be patient.
I do not recommend making transparent soap, if you never did soap from scratch, as the technique is quite complex and requires at least an experience from the cold process technique.
The recipe I use here is a rescaled version of the Basic Recipe 2 (page 66) of the book Making Transparent Soap: The Art Of Crafting, Molding, Scenting & Coloring by Catherine Failor.
If you wish to make transparent soap on a regular basis, I highly recommend you to buy this book. It has a perfect troubleshooting section and much much more information I could possibly give you here.
Basic theoryWhat gives the transparent soap its transparency are solvents.The soap crystals must be dissolved so that the light can pass through. Thus, transparent soap is a mixture of actual soap and solvents, which is reflected in the whole process:
- first, the soap is made by a hot process method and
- then the solvents are added to make the soap transparent.
- only after that soap can be poured into molds.
The water should be distilled. Hard water can contain minerals and salts that can cause cloudiness.
Absolutely the best solvent of soap is alcohol, followed by glycerin and sugar syrup (sugar in distilled water). I do not know exactly, why in all recipes we do find always all three of these, seems that they complement each other. I do plan however try different batches in different combinations of these… Here what the theory says:
- Alcohol – According to C. Failor, it is impossible to make a transparent soap without alcohol. Or, it is possible, but such a soap looses its transparency with time. The best alcohol is denatured ethylalcohol of 90%. I add that you can use instead a propylene-glycol, which will make your soap meltable => you will obtain a meltable M&P soap base!
- Glycerin – Glycerin is another good solvent, which has in addition also a moisturizing effect, however, it is highly hygroscopic – attracts water. If there is too much glycerin, the soap will be soft and sticky as it will be attracting water from the humid air in the bathroom. The soap will look like if it was sweating. Too much glycerin also causes cloudiness .
- Sugar solution – Sugar is also an excellent solvent, apparently gives the final touch – without sugar the soap is not fully transparent. Disadvantages are the same as for glycerin – too much causes soap sweating and cloudiness.
Given the large amount of solvents added to the soap in order to achieve its transparency, recipes giving hard soap bars are preferred.
The oils giving hard soap bars are those containing high fraction of saturated fatty acids, like tallow, palm, palm kernel or coconut oil.
Palm oil or tallow do not dissolve readily in the water, therefore the soaps are not very bubbly.
Palm kernel oil or coconut oil – create very bubbly and hard soap, but it can be drying.
It is of interest then to add soft oils.
As a soft oil of choice is usually selected castor oil- it mainly consists of ricinoleic acid, which gives soap with particular qualities, ideal for homemade transparent soap.
- it attracts water – therefore is humectant – produces conditioning bar
- it is readily soluble – therefore is partially translucent and produces nice bubbles
If you want to design your own recipe, here is the guide to calculate the % of solvents (summarized according to C. Failor):
Alcohol: 30 – 35% of actual soap mass (defined as oils + solid NaOH in the recipe, without water!).
Glycerin: 8-12 % of overall recipe (defined as oils + NaOH + water – both for NaOH and for sugar solution)
Sugar: 6-9 % of overall recipe
Water: 12-20% of overall recipe (defined as oils + NaOH + water – both for NaOH and for sugar solution)
Recipe & Instructions
In overall, it is more precise to work with grams (I did work with grams) than with ounces, because in the transparent soap, each small difference matters.
|Distilled water||327g||11.5 oz||1 pound 9 oz|
|NaOH||157g||5.54 oz||12 oz|
|Oils and fats|
|Palm oil||340g||12 oz||2 pounds 8 oz|
|Coconut oil||353 g||12.45 oz||1 pound|
|Castor oil||340 g||12 oz||1 pound 9 oz|
|Glycerin||196 g||6.91 oz||8 oz|
|Ethylalcohol||380 g||13.4 oz||1 pound 12 oz|
|Sugar||236 g||8.32 oz||1 pound 4 oz|
|Distilled water||170 g||6 oz||15 oz|
First two steps are common with the hot process method:
- Mixing the lye solution and oils at 50°C (122°F) to trace.
- Heating the soap mass until the end of the saponification process – gel phase -> Ph testing (~2-3 hours)
- If the Ph is OK, the soap is dissolved by adding the mix of glycerin and alcohol to the soapmaking pot:
- Weigh together your glycerin and alcohol according to the recipe
- Slowly pour this liquid to the soap mass in the soapmaking pot. ATTENTION!!!SOAP MASS IS HOT AND ALCOHOL IS HIGHLY FLAMMABLE, EASILY EVAPORATING – BEWARE OF HOT ALCOHOL VAPORS THAT SHOULD NOT GET CONCENTRATED AS THEY CAN START BURNING EASILY – AIR WELL YOUR WORKING SPACE !! IF YOU USE OPEN FLAME, PAY ATTENTION NOT TO POUR THE ALCOHOL IN THE FLAMES!!!! – this is why I use crockpot…
- Mix everything thoroughly until the soap dissolves in solvents.
- Weigh together your glycerin and alcohol according to the recipe
- Let the mix on low heat for about 30 minutes (HIGH in crockpot). Cover the pot with a lid – it should be air-tight, otherwise the alcohol will evaporate. C. Failor recommends using a plastic sheet fixed with ropes instead of a lid, however, I find it a bit complicated and finally I didn’t need it – my crockpot lid worked well.
- While waiting, prepare your sugar solution (I highly recommend to prepare double of the needed amount – you will need it later for the adjustment of the transparency if it does not work on the first try):
- Weigh distilled water in a pot and add sugar
- Bring to boil and immediately turn off – the water should not evaporate and the rest of the sugar will dissolve in the hot water.
- After 30 minutes add the sugar solution to the soap solution and mix well.
- Remove the sticky foam from the top and put it in some mold – it can be used as a soap after cooling.
- Test for transparency:
- Take a frozen glass from the freezer and turn it upside-down. Pour about one tablespoon of soap on the bottom. The hot soap solution is always transparent, so you can judge on final transparency only after cooling – because the glass is frozen, the cooling will be fast. If you see pronounced milkiness you have to add more solvents.
- If the transparency test was unsuccessful, add small amount of the sugar solution(see, this is why it is good to prepare more!). Repeat maximum twice, each time testing for transparency, if still pronounced milkiness, switch to alcohol or glycerin. Do not add too much solvents, because this causes sweating and on the contrary – milkiness.
- Small amount of sugar solution means 40g (1.4 oz) for this concrete recipe. Just calculate the percentage and amount for your own recipe to get the weight you need.
- I added the sugar solution twice, I didn’t want to risk more.
- Repeat 8 and 9 until transparency. This step is very critical and you need all your patience (I do not have it). It can take an hour or just few minutes if you are lucky. Do not hurry, the soap solution is ok on the low heat for a long time.
- When you are happy with the transparency, color and scent your soap solution. Attention, the color can affect the transparency. Good news is that you can use any food coloring without them changing color, as the saponification is already finished!
- Finally, pour the soap into molds – the best are one bar molds – we want the soap to cool as quick as possible – this also ensures transparency. Put the forms in the fridge. When pouring, small bubbles will create on the top (and as I found, not only on the top :-/ ) – disperse a bit of alcohol, that should dissolve the foam.
- When the soap is cooled and solid (this is really a matter of 1-2 hours in the fridge), unmold it and then
- Let it age for at least 4 weeks – this is my personal experience from this batch – the alcohol and water evaporates, soap is getting harder, increasing its life span. it also does smells much less of alcohol – eventually the smell will disappear (I hope so!)
Enjoy and let long live your bar of soap!