Calculating your water amount for soapmaking

water in soapmaking

water in soapmaking

I get questions all the time about how I come up with my water amounts. I do not use a lye calc to get my water amounts. I simply use a lye calc to get the correct amount of lye to use.

My standard water used is equal to 2 times the lye. So if a recipe calls for 12 oz lye, I will use 24 oz water. This is even true for advanced swirling recipes. You hear a lot “use full water for fancy swirls so that you have time to play”. I create my slow moving recipes with special mind to the oils more than the water amount.

I can’t stand unmolding soap the next day and for it to be softer than play dough. (This is what you get when using a water:lye ratio of 3:1 or 4:1 plus soft oils such as olive that contribute to a slow moving recipe.)

For recipes high in olive oil and other soft oils (50%+) I will use a water amount equal to 1.5 times my lye. Why?

High olive oil recipes are longer to trace, softer initially upon unmolding and typically take longer to cure. Discounting the water helps with all of these issues. It speeds up trace (though still allows plenty of time to design the soap), makes a harder bar for unmolding and reduces the cure time.

When I am doing a 90-100% castile or bastile type of soap I will actually use 1.1 times my lye. So if a recipe calls for 8 oz lye, I will use 8.8 oz of water.

You should never use less than 1.1 times your lye. Lye needs at least an equal amount of water to form a solution. If you use less water the lye will actually fall out of solution and you will not have properly dissolved lye. I typically add the .1 amount to just give myself a bit of a buffer.

Take care when working with a higher concentrated solution. Your soap will move faster, your solution is stronger which means it could burn fast/worse and keep an eye on it when you initially make it as it heats up faster and hotter.

I prefer ratios and I prefer simplicity. 2 times lye, 1.5 times lye and 1.1 times lye are really easy to remember and figure out.

The amount of water you use is simply a personal decision. There really isn’t a right or wrong but it can effect the way a recipe moves, sets up and cures out.

-Amanda

51 Responses

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  1. Salome

    This is interesting and I will try it. Will this also work for hot processed soaps?

    · Reply
    • Author

      I use a ratio of 3:1 or 2.5:1 (water:lye) for hot process just because some of it evaporates during the cook.

      · Reply
      • HP seems to only lose about 7% of the input water per hour of cooking (180F double boiler). Out of impatience, I decided to try HP with water discount.

        1.1:1 seemed intimidating, so I used 1.3:1 in a 6 pound batch. This was 2400g oils, 293g NaOH, 384g H2O, 60 grams of additives. Superfat was 11% per soapcalc, but based on moles and weights, it was closer to 7%. I still need to measure the pH to confirm exactly, but I’m expecting high nines.

        It was my first time to discount below 2:1, and it was a game changer. It ran WAY hotter and much faster. Overall though, this was great. The soap is so much more firm. I cut it at 3 hours, and at 9 hours, it’s harder than my 4:1 soap that’s been cooked 3 times and cut for 2 days. (4:1 was an error in late water addition).

        Next DWHP, I’ll stir immediately rather than putting the lye pot in the sink. I won’t use additional heat once it emulsifies. I’ll start working on the color/scent additives at early oatmeal rather than stirring it again. Lastly, I won’t use my stick blender as a spoon against the volcano.

        · Reply
  2. Brilliantly said! Solution/oil temperature can also make a difference in workability time without increasing water.

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  3. Hilda Bahner

    Amanda,
    Thank you so much for this valuable information.
    Hilda Bahner

    · Reply
  4. Gudrun

    Thank you so much for this informartion. Finally!! You have the best information and instructions on soap I have seen. Wish I lived close enough to take one of your classes.

    · Reply
  5. Thanks so much for the great information! I love the way it simplifies things. I have tried it on the last eight batches I have made and it worked great!

    · Reply
  6. Dee Huffman

    I make more hot processed soaps so I will try using your method of calculating. I have finally moved into swirling and could see this as beneficial when I do multiple colors. Allowing myself better control. Thanks again for another excellent lesson. Hope to see you when you come to NY. Dee @ Yada Soaps

    · Reply
  7. Ambereen

    3 words for the site/ blogs
    AWESOME AWESOME AWESOME!!!

    its in my favorite websites…..
    VERY HELPFUL SITE…..

    · Reply
  8. Thank you for posting this. Now that I am working on my own formulations I began questioning how I could better account for the amount of water I used.

    · Reply
  9. Hi Amanda,

    Thank you! What happens when you use aloe vera juice in place of water? Does the ratio remain the same?

    · Reply
  10. Marion

    Hi Amanda, I made soap yesterday using your calculations but Im not sure I did it right.
    My recipe was 70% olive oil and 30% coconut. I used soapcalc’s calculator. I put in water:lye ratio box: 1.5:1 (I also did it leaving 38% in water as % of oil) and then multiplied that by 1.5. Each time I came up with 64.552 grams of lye (2.227 oz) leaving me with a calculation of 64.55 x 1.5 = 96.82 grams water (3.416 oz). When I unmolded it this morning it came out easily but when I tested it with phenolphthalein solution, it showed pink and the bars are whitish and a bit crumbly on all sides and edges. I noticed that I did take a 5% superfat discount too. Im now thinking its lye heavy because I took the discount in addition to the 1.5 calculation.

    So I guess my question is: when calculating our water amounts in soap calc, do we leave in the 38% to get our lye amount and then multiply from that number and NOT take an extra discount?

    II recently found your blog and am very much enjoying it. THANK YOU

    · Reply
    • Author

      Hi Marion,

      I’m not sure I’m exactly following what you did. Can you send me the whole recipe including oils?

      If soapcalc gave you a lye amount of 2.227 oz then you should have multiplied it by 1.5 to get your water. It gives you 3.34 oz. There can still be active lye in day old soap especially if the soap did not go through gel phase. This can also make the soap crumbly.

      · Reply
      • Marion

        I just tested again with the solution and it didnt turn pink. So I now think that due to my small batch size it didnt gel (in fact I recall now that when I checked on it an hour or so after pouring that it wasnt as warm as I thought it should be) and this is what caused the outside to be white and crumbly, and that its ph tested too high because I used phenolphthalein solution too soon after unmolding (that day in fact).

        Thank you for your response and for all your good information.

        · Reply
  11. Angela

    Hi Amanda, I wound up with soap on a stick when I did the Rice Bran recipe you gave us. I really don’t know what went wrong but it became really warm in my containers and the worst thing or maybe the best thing depending on how you look at it is that I never even got to add any fragrance. I really don’t know what went wrong but I am going to rebatch it today. Thst was some experience. Thanks for the recipe anyway. The only thing I did was the water discount you recommended with the recipe.

    · Reply
    • Author

      Hi Angela! Hmmmm that is interesting as this recipe is usually pretty easy to manage. Perhaps your lye and oils were too hot? Heat can makes things move fast. Also, what kind of olive oil did you use? Pomace can make things move fast. I usually use Grad A regular olive oil.

      · Reply
  12. Marion

    Stupid question? Do you take a lye discount before calculating water amount?

    · Reply
  13. Tari

    I am new to soap making. I am doing a lot of research so this question may be really silly but What if you wanted to add coconut milk to your recipe? Does that change the amount of water used in your recipe to dissolve the lye or do you treat it as an additive? I hope that makes since….

    · Reply
    • Check the container. Probably not. Our coconut milk is something like 4 grams of fat and 6 grams of carbohydrates per 245g of liquid. That’s less than 0.1g of lye to adjust.

      The main thing to do is to keep the temperatures down while mixing the lye. If it gets too hot, it can scorch the milk or boil over on you.. The calories in the milk will all try to react when you add the lye, so either add slowly over several minutes, pre-chill the coconut milk (semi-frozen slushy), or mix it while it sits in an ice bath.

      The same thing applies to wine soaps, except assume that 13% of the volume is alcohol, not water, and will evaporate very quickly. Add extra wine to compensate, and again, mix slowly so you don’t overheat from the sugars and boil over.

      · Reply
    • Author

      Hi Tari – there are two ways to use milk in soapmaking. You can either use milk in place of water. I have a couple of tutorials on using milk. http://www.lovinsoap.com/2012/10/how-to-make-goats-milk-soap-using-farm-fresh-goats-milk/ and http://www.lovinsoap.com/2011/01/creamy-carrot-cold-process-soap/

      You can also make a lye solution with lye and water being equal parts. Then add the same amount of milk to the oils before you add the lye solution.

      So if your recipe calls for 4 of lye… make your lye solution with 4 oz lye and 4 oz water. Add 4 oz milk to the melted oils. This method helps to keep temps down and milk from burning. Email me if you need more info amanda@lovinsoap.com

      · Reply
      • Tari

        Thanks so much for all of your responses to my questions. It’s been so helpful for me. I’m loving this site!

        · Reply
  14. Tari

    I guess I am not finding in my research how to figure out the amount of coconut or goats milk to use in a recipe. It’s not something that I can add to the calculators like soapcalc to help me figure it out.

    · Reply
    • Sorry, my edits said “check the container” but that was a thought tangent about calculating calories.

      Really, no adjustment for milk is needed. You might adjust for heavy cream (mimicream?) if you were making a big batch.

      · Reply
    • If you’re still worried, consider that it’s roughly 1 gram of lye for every 75 calories. That’s probably less than the measurement error any of us has in making a batch unless it’s really high-calorie milk.

      Note, that’s a rough estimate. Short chain fats like stearic acid would want more lye, and long chain fats want less. It’s basically 3 moles of NaOH for every 1 mole of triglycerides. The Na bonds to the fats, and the OH bonds to the glycerol (glycerine).

      Carbohydrates would vary a lot more depending on the sugars and starches invovled.

      · Reply
        • Yup, I flipped it. Though, none of the fatty acids we use for soap are formally “short” either. Double whammy.

          Stearate does count as a “long” chain by 2 carbons.

          But the context stays the same, in that the longer the aliphatic tail, the higher the molecular weight, and therefore lower amounts of reagent (by moles) are required to convert a given mass.

          Sorry for the error.

          · Reply
  15. tammy l wilson

    I can`t wait to start making a new batch of soap Thanks for all the insight

    · Reply
  16. My last soap was very soft the next day and it had water to lye ratio of 2,78:1.
    I’ll use your method next time and make a 2:1 recipe. Thank you for the advice.

    · Reply
  17. C Perez

    Thank you. I’m new to soaping and your site has been very helpful. The water in the recipe not matching the lye calculator was confusing me.

    · Reply
  18. This was very helpful! I have a question, though. I have a small mold that gives me the size bar I want with a 1.25 pound recipe. I currently use 2.5:1 for lye. If I dropped down to 2:1 or 1.5:1, will it make for a smaller bar of soap? My goal is to get a bar of soap that is the same size as 2.5:1 gives but weighs more after curing. Thanks for your help!

    · Reply
    • Raw, dry, compressed soap has a lower density than water. If you have less water, then your bar of soap at the same size will weigh less, but last longer.

      Soap is 0.932g/ml and water is 1g/ml.

      · Reply
  19. Sonia Franco

    Hi: Last night I did my first batch & seems that I made a LOT of mistakes. A lot of soft oils and the ratio of water… don’t really want to talk about it …lol. Now I have a really good smelling playdough and I have no idea how to fix the BLOB.. I don’t want to throw it away cause my daughters( 7&6 yrs) are so happy that they helped me and the BLOB are their baby…What can I do..PLEASE????

    · Reply
    • Author

      Oh no! Let it sit and it should harden up. It might take closer to 5-6 weeks to cure. You could have the kids roll it into cute little balls and just set it aside to cure. :)

      · Reply
  20. Angela

    Hi Amanda,

    I am soap making newbie and would appreciate some advice on the following..

    I tried a new recipe with the following: Olive oil 38%, coconut oil 28%, castor oil 6%, palm oil 28%, lye 1.7 oz, water 3.9 oz which yielded 17 oz of soap. I mixed oils and lye at 110 F. I poured the contents after getting a trace in to wooden mold lined with freezer paper and allowed it to sit for 24 hours in a cardboard box wrapped in a cloth. While attempting to remove the soap from the mold and while cutting the soap appears to be sticky and not completely dry. So does this mean that I need to let it dry for longer? Attempt a different way of drying the soap? Should I change/percentage of oils OR Water? My previous attempts with other oils has also resulted in soaps which are sticky even after 48 – 72 hours of drying.

    Thanks,
    Angela

    · Reply
  21. Becky

    What would the suggested water/lye ratio be for liquid soaping? I just made my first batch of liquid soap and it turned out pretty good…a bit cloudy but for personal use, it is fine. I used a 2.5:1 ratio for that batch. Is that what you would suggest…even for single oil soaps? Thank you.

    · Reply
  22. daniela craciun

    Hi.
    the 1.1 ratio of water-lye is avalable for liquid castile soap too?

    · Reply
  23. solomon

    hi man I will like to know how to calculate the amount of oil for the soap after picking ur recipe. or it actually doesn’t matter the amount of oil u use
    .???

    · Reply
  24. shams

    Hi ! I want to start new business of soap in pakistan , i have confusion about the recipies of bathing soap , laundri soap nd pot wash soap ,I have also confusion about the water ratio for oil nd lye , pleas email me some good recipie for 2.pound , 3.pound , 5.pound soap .can i add extra water after mixing of oil nd lye , or at start for lye solution the water is suficient . Also inform about the hot nd cold process . Email me some qualitiy recipies with clear example on shamasbm@gmail.com.

    · Reply
  25. Cathy

    Hi! And thanks for this tutorial. I love the concept and have been concidering this same thing for a while. I’m glad someone else had the courage to try it first :)

    Last night I did a small 1 pound test batch very basic shampoo bar recipe with coconut, olive oil pomace, and castor oil and water as my liquid at a lye discount of 3%. I did the 1.5 time the amount of lye,mixed oils and solution at 103 deg. It traced fine,but not as quickly at I was expecting,and didn’t heat up like you suggested. I use a wood box mold with lid and even wrapped in towels and still it did not gel,which I found odd. It looks nice and is normal other than not passing zap test yet but it’s been only 12 hours also. Should I have mixed oils and lye solution at a higher temp, if I want it to gel? And because this is so low on water is it going to zap worse or for longer than normal? At 24 hours, with normal method I can umold pass zap test and cut.

    · Reply
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