Understanding mold capacity
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Water discount
No answer to your question but I also have a follow-up question about accounting for water discount. Tried the .4 multiplier with a water discount and it didn't fill my mold.
The stickied thread on estimating oils has a post that says that the .4 multiplier is equivalent to the water % of oils and to simply multiply by .35 if you are using 35% water. But somehow that doesn't make sense to me. If you multiply by .35 instead of .4, that should give you less soap, right?
No answer to your question but I also have a follow-up question about accounting for water discount. Tried the .4 multiplier with a water discount and it didn't fill my mold.
The stickied thread on estimating oils has a post that says that the .4 multiplier is equivalent to the water % of oils and to simply multiply by .35 if you are using 35% water. But somehow that doesn't make sense to me. If you multiply by .35 instead of .4, that should give you less soap, right?
VanessaP
Well-Known Member
That won't change a whole lot unless you're doing salt bars. When I do additives like oatmeal, I used one tablespoon PPO and it was just way too scrubbie (very finely ground in my coffee grinder) so I wouldn't do more than 2 teaspoons, tops, again. The .4 takes into consideration oil amounts, but it doesn't take into consideration for a water discount, so you should be perfectly fine if not doing full water. I had to bump my 3lb batch in oil amount by 3-4 oz because I tend to do a 32-34% lye concentration instead of full water, for CP, and that is over a 4 oz difference of water for my batch.
I just thought with a whole oz of scent you'd need a smaller recipe. The molds according to the equation needs a 17.5 oz batch but that seems like alot for just 4 of 5-oz cavities. I normally do about 4.7 half milk half water.
I agree, the 2 tsp of clay or oats I do per pd is not much.
I agree, the 2 tsp of clay or oats I do per pd is not much.
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Kansas Farm Girl
Well-Known Member
As you know, when you use the formula for calculating the mold volume you take the length x width x depth. This gives you the total volume of your mold in square inches (or your preferred unit of measure, I will use inches here) and you would use that if you want to fill it all the way to the top.
When you take that total times 0.40 you are calculating the percent of oils you will use in your recipe. But they never tell you how they got to 40% for this calculation, nor have I been able to reverse engineer it and come up with it - math is not my strong suit.
For example, if your mold is (inches) 10x3x5= 150 square inches. 150 x .4 = 60 oz of oils and the rest for water & additives.
A discount of 35% of your oils you get 60*.35 = 21 oz oils or total soap of 60 + 21 = 82 oz. But your mold volume is 150. So how does 150 square inches equate to 82 ounces of soap? If you have a cube that is 1 inch x 1 inch x1 inch, approximately 0.55 ounces of oil fit into that cube. Take the mold size in square inches * .55 or (150 *0.55=84 ounces). This is the maximum number of ounces you can put into that mold, whether it be oil, water or additives. If your totals add up to more than 84 you will have more soap than your mold will hold.
Of course you can give yourself a fudge factor in not measuring the full depth of the mold. In this case I said it was 5 inch deep. But you could use 2.5 if you wanted your bars to be 3 inch wide and 2.5 tall (10*3*2.5=volume). Any water discount under 40% will give you a bit extra room also. 60 oz oil w/35% discount is approximately 21 oz water (total soap 81) and a 32% is 19 or 79 oz soap, both giving you less soap than will totally fill the mold.
Sorry to be long winded, but I was working this out so that I understood it too. If I haven't figured something in let me know, but SoapCalc agreed with my water volumes when I ran test scenarios through it. I put on 60 oz oil and 35% water discount and compared that to my spreadsheet and had the same number, same with others I used to test.
When you take that total times 0.40 you are calculating the percent of oils you will use in your recipe. But they never tell you how they got to 40% for this calculation, nor have I been able to reverse engineer it and come up with it - math is not my strong suit.
For example, if your mold is (inches) 10x3x5= 150 square inches. 150 x .4 = 60 oz of oils and the rest for water & additives.
A discount of 35% of your oils you get 60*.35 = 21 oz oils or total soap of 60 + 21 = 82 oz. But your mold volume is 150. So how does 150 square inches equate to 82 ounces of soap? If you have a cube that is 1 inch x 1 inch x1 inch, approximately 0.55 ounces of oil fit into that cube. Take the mold size in square inches * .55 or (150 *0.55=84 ounces). This is the maximum number of ounces you can put into that mold, whether it be oil, water or additives. If your totals add up to more than 84 you will have more soap than your mold will hold.
Of course you can give yourself a fudge factor in not measuring the full depth of the mold. In this case I said it was 5 inch deep. But you could use 2.5 if you wanted your bars to be 3 inch wide and 2.5 tall (10*3*2.5=volume). Any water discount under 40% will give you a bit extra room also. 60 oz oil w/35% discount is approximately 21 oz water (total soap 81) and a 32% is 19 or 79 oz soap, both giving you less soap than will totally fill the mold.
Sorry to be long winded, but I was working this out so that I understood it too. If I haven't figured something in let me know, but SoapCalc agreed with my water volumes when I ran test scenarios through it. I put on 60 oz oil and 35% water discount and compared that to my spreadsheet and had the same number, same with others I used to test.
My regular soapmaking bowl measures that I have over 20 oz of soap batter by volume with everything added and it's about to trace. (Typical 1 lb recipe). So I also measured each cavity in my new mold by volume and the 4 were exactly 5 oz each in a measuring cup.
Different oils weigh more than others and coconut oil is heavy I was told by a chef friend. So I don't know how the equation works for all soap recipes. The last one I did was a salt bar recipe for 2 bars but 8 oz of mostly all coconut oil was pretty shallow before the salt. I couldn't believe an 8 oz recipe plus 2.4 oz water plus lye and scent, plus 3 oz of salt made just over 2 bars in the new mold. Water doesn't evaporate that quickly. Then I thought about the weight of co and I think that was the deal. It was all weighed correctly too, and triple-checked on the scale minus the 6 oz of the smaller mixing bowl I used for this.
I think I'll do my old 16.5 oz loaf recipe and see how much I come up short. I'd rather do that than have more soap made than I need with extra supplies than necessary used up.
Different oils weigh more than others and coconut oil is heavy I was told by a chef friend. So I don't know how the equation works for all soap recipes. The last one I did was a salt bar recipe for 2 bars but 8 oz of mostly all coconut oil was pretty shallow before the salt. I couldn't believe an 8 oz recipe plus 2.4 oz water plus lye and scent, plus 3 oz of salt made just over 2 bars in the new mold. Water doesn't evaporate that quickly. Then I thought about the weight of co and I think that was the deal. It was all weighed correctly too, and triple-checked on the scale minus the 6 oz of the smaller mixing bowl I used for this.
I think I'll do my old 16.5 oz loaf recipe and see how much I come up short. I'd rather do that than have more soap made than I need with extra supplies than necessary used up.
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The formula is in inches, LxWxHx.40. Yes, the volume of one cubic inch is 0.55 fluid ounces. But we are converting from a fluid volume to weight, and estimating the amount of oils needed to make enough soap batter to fill the mold. 0.55 fluid ounces of water also weighs 0.55 ounces (at sea level, but close enough for our purposes here), but 0.55 fluid ounces of oil does not weigh 0.55 ounces. It weighs less. 0.4 ounces of oil by weight will take up more volume than 0.4 ounces of water. If you add one gallon of water to one gallon of alcohol, you will have less than 2 gallons volume, even tho the weight will be the total of the 2 combined. Same principal with soap. Adding all the ingredients' weights together will give you the total weight, but the volume will be less than sum of the oils and lye water.
It is a good basic formula, not a hard and fast rule as there are a lot of variables. If you are taking a bit of a water discount, adjust your formula a bit to compensate. I know there is a different formula for using metric, I don't know it tho, but I am sure we can find it or do the math to figure it out if anyone needs it.
It is a good basic formula, not a hard and fast rule as there are a lot of variables. If you are taking a bit of a water discount, adjust your formula a bit to compensate. I know there is a different formula for using metric, I don't know it tho, but I am sure we can find it or do the math to figure it out if anyone needs it.
paillo
Well-Known Member
Ditto! Except it hasn't always worked for me for several months, anyone else have a problem with results being way off?
Thanks for all that! I'm doing the recipe tonight and I don't have enough scent to go over 16.5 but since it's going to be a standard recipe it will tell the tale of wheither it's enough or short for the cavities. I'm thinking that milk soaps end up bigger than water soaps because the water dries and the milk stays and saponifies.
Defininitely going to check out Summer Bee Meadow and not struggle with this any more after tonight, hoping!
I'll probably not be able to buy one oz samples of scent for a 17.5 oz batch if the cavities need that much unless the scent is strong and can go 5-5.5% on it. This is a new Oatmeal Milk and Honey scent and doesn't seem to be super strong.
Defininitely going to check out Summer Bee Meadow and not struggle with this any more after tonight, hoping!
I'll probably not be able to buy one oz samples of scent for a 17.5 oz batch if the cavities need that much unless the scent is strong and can go 5-5.5% on it. This is a new Oatmeal Milk and Honey scent and doesn't seem to be super strong.
Kansas Farm Girl
Well-Known Member
I have a spreadsheet lye calculator that has the volume equivalent for each oil. I haven't used it enough to know how accurate it is. I always try to give myself a bit of fudge factor when figuring how much soap to make for a mold. I do have some individual molds that I can fill if I mis-calculated my loaf.
I did just get a silicone mold that has 12 individual bars. I haven't tried it yet, so am not sure how much it will hold. I think that a 16 oz recipe should fill them, but won't know until I try it - glad it's the weekend, maybe I will have time.
I did just get a silicone mold that has 12 individual bars. I haven't tried it yet, so am not sure how much it will hold. I think that a 16 oz recipe should fill them, but won't know until I try it - glad it's the weekend, maybe I will have time.
new12soap - I don't understand half of what you said but I just wanted to say that I'm coming to you with my next math problem.
LOL EEEEEEK! I'm sorry, I was actually trying to simplify it, I guess I didn't do a very good job!
But yeah, sure, I am happy to try to help with a math problem
I just multiply the amount in ounce by 28.35 to convert to grams. Or you can also use this: http://www.metric-conversions.org/weight/ounces-to-grams.htm
Thanks for all the comments. I do adjust for water discount but essentially I just make a guess, so I was wondering if anyone has a more foolproof method.
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