How much soap would this mould hold?

Hi could anyone tell me how much soap I need to fill this slab mould, 43 x 21 x 2.5 cm? Thank you.

You'd need 55 oz oils I think.
That would yield a little over 5 lbs soap.

I had to convert cm to inches, then take length times width times height and multiply by .4 (or 40%) to get the oil amount. Then I plugged a quick test recipe into soap calc at 55 oz oils and it yielded before cure 5.3 lbs soap. Not promising I did this right. Hopefully someone can check me on this.

Here you go..... [ame]https://www.youtube.com/watch?v=018-zZOTLwM[/ame]

Thank you so much for time and effort. I am nowhere near as educated in these precise calculation matters...

I have a handy converter app on my cell. It converts everything! Very handy;-)
Edit to say I realized you probably use metric, in which case soap calc will tell you the grams amount after you plug in the 55 ounces in oils amount. Click print and it shows ounces, pounds, and grams. I'm sure you know this, but I wanted to mention for others that may be new to this.

http://www.soapmakingforum.com/showthread.php?t=2909

From a sticky at the top of this section

Well I'll have to disagree with the 55oz. My calculations are 76oz of soap to fill that. Now if the question is how much oil do you need to fill that, then the question would be what % of water do you use, what SF % and what amount of fragrance do you use.

If you are using the 38% H2O that many use, then the 55oz is a close estimate of the oil needed.

There's a lot of things that go into figuring out amounts from a final volume, and people often miss some key steps or do some inverse equations that seem right, but are not.

What do you really need to know, a recipe to to fill that mould? Let us know the % of H2O you want to use, the SF% and the fragrance amount per lb or kg f oil

Yes, 38% water and 3 to 4% essential oils.... Any recipe would fill that mould, of course, am just after how much oil I need. Thank you again.

I was saying 55 ounces of oils, not final soap batter.
If you want the oils, fats, and butter amounts and you click gents link to calculating soap mold volume, and it says virtually the same as I did.

You take length x width x height in inches, and then you multiply it by 40% which is .4 to get your total oil/fat/butter amount. The oils is 39-40% of the total weight of your soap (depending on who you ask).

So converting the centimeters to inches, multiplying length width and height, then multiply by .40 it becomes
16.929 inches x 8.267 inches x .984 inches = 137.712810312 cubic inches.
Now multiply this by .40 (or 40%) and you get 55.0851241248 ounces of oils needed.

So I rounded to 55 ounces. Go to soap calc and plug in 55 ounces worth of olive, coconut, palm, whatever you want and the TOTAL amount of Soap will be appx 5 pounds of uncured soap, give or take, seeing as different water amounts, additives like salt, and different oils weigh slightly different.

They may wind up with 4.8 pounds, or 5.5 pounds of uncured soap, but they'll need about 55 ounces of oils to make the 5 pounds of Soap.

Hope this clarifies

RogueRose said:

Well I'll have to disagree with the 55oz. My calculations are 76oz of soap to fill that. Now if the question is how much oil do you need to fill that, then the question would be what % of water do you use, what SF % and what amount of fragrance do you use.

If you are using the 38% H2O that many use, then the 55oz is a close estimate of the oil needed.

Click to expand...

Also to clarify, superfat has nothing to do with the oil amount. It has to do the the amount if lye. Less lye equals more free oil in the finished bar and higher superfat. More lye saponifies more oil turning it into soap with a less superfat. Water evaporates out and has nothing to do with oils either, but rather has to do with lye and dissolving. more water yes, will cause your final soap to shrink more since more evaporates out causing a final bar smaller than it would've been with less water. Either way, this method I used is a fairly good way to discover the amount of oils you need for a soap mold.
Edit, it figures the oil amount, 40% of total volume, and the remaining 60% accounts for lye, water, colorants, fragrance, etc.

lionprincess00 said:

Also to clarify, superfat has nothing to do with the oil amount. It has to do the the amount if lye. Less lye equals more free oil in the finished bar and higher superfat. More lye saponifies more oil turning it into soap with a less superfat. Water evaporates out and has nothing to do with oils either, but rather has to do with lye and dissolving. more water yes, will cause your final soap to shrink more since more evaporates out causing a final bar smaller than it would've been with less water. Either way, this method I used is a fairly good way to discover the amount of oils you need for a soap mold.
Edit, it figures the oil amount, 40% of total volume, and the remaining 60% accounts for lye, water, colorants, fragrance, etc.

Click to expand...

But then if the 60% is the lye and water, changes to the SF and water amount will then change how many grams/oz that 40% is.

But generally speaking, those calculations are great starting places.

Yes, starting place only! Try using 100% salt ppo for salt bars and the salt will wind up almost doubling the final weight! Start with this and adjust as needed. Be prepared to have an extra mold on hand in case you wind up with a little too much soap.
I have individual round silicone cavities mold that I always bring with me in case I have too much soap. Love my rounds, they let me have a practice soap I can use day 3 or so, and periodically use it to see how it cures over time, and I usually make a tad more soap on purpose to have these little extra soaps lying around.

TLDR all the posts, but those saying that oil is 40% of the recipe are VERY far off.

Let's say we use the default 38% water, 5% superfat and 41g of fragrance per kg of oil (18.63g per lb) - that is about 30% more than the .5oz/lb of oil standard in some calculators - this is really negligible in the rest of the calcualtions.

So if the dimensions are 42 x 21 x 2.5 = 2.258L or 2,258cc's/ml's

Now the problem using weights vs volumes is that each oil has a different density, all lower than 1g/ml.

If you plug the following into a calculator you will get your needed amounts:
Oils = 1,458g = 64.51% of total volume
Water = 554g = 24.51% of total volume
Lye (NaOH) = 188g = 8.32% of total volume
Fragrance = 60g = 2.65% of total volume


The differences are that the lye has a density higher than 1g/ml, the oils are usually .87-.96g/ml, h2o is 1g/ml and fragrance oils can be .85-.98g/ml. All this has a bearing on the total weight of the soap and for some reason when I make the lye water with say 1000g h20 and 400g lye I always get an amount less than the sum of the two from 2-10%! IDK where it goes...

Ok...so, uh...how much do I need in the end?

loopyloop said:

Ok...so, uh...how much do I need in the end?

Click to expand...

I plugged your numbers into SoapMaker3, which will give you amount of oils and estimated volume.

Amount of oils. 1533.39 gr
Approximate finished volume 77.121 fl oz or 2280.738 ml's

Ok loopy, it seems like it's been over complicated, and I'll take blame and say sorry about that!! I do that often I've been told lol.

Most soapers use the formula -----

Length x width x height in inches

Multiply it by .4

That's your oils amount in ounces.
-------------------


For your mold, use 55 ounces oils. Your finished product will yield between 4.75 and 5.3 pounds of Soap depending on your additives and water amount.

This is the method most used. It isn't perfect, it isn't exactly accurate, and usually after used you'll see you may wind up needing a little more or less oils next time. Maybe someone has a perfect formula for precise calculations, but this is the closest I've ever come across, read, and used.

I've seen it on numerous websites (including the sticky here). To see this method, here are some helpful links. The video is excellent, I highly recommend you watch it. she uses .39, and others use .4 like I suggested. It's very close either one you choose to use.

http://www.soap-making-essentials.com/calculating-moldrecipe-size.html


http://www.newenglandsoaps.com/how-much-oil-do-you-need-for-your-mold/


[ame]http://m.youtube.com/watch?v=018-zZOTLwM[/ame]


http://www.soapmakingforum.com/showthread.php?t=2909

actually princess you brought up some great points. Try using that lxwxhx.40 on a 100% salt soap and watch how far off it is.

It's a good starting point.

Thank you, am happy to try 55oz... Grateful for the discussion.