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#### gigisiguenza

##### Well-Known Member
In my research the formula I saw everywhere for determining the amount of oils needed based on the mold's volume is this
l x w x d = volume
volume x .40 = amount of oils needed for a batch to fit that mold

Now, the reason I'm asking is that I was watching a video tutorial on YouTube by Soap Queen or Soaping 101 (can't remember which) and the formula they used was
volume x .39 = amount of oils

When I ran the recipe for my first batch through soapcalc to get all my specific measures, I used the amount of oils that the volume x .40 formula gave me. The batch came out fine, no issues, but now I'm curious which formula is correct, and if the residue that was on my little loaf and left in the mold were actually excess oils because I had actually used too much, based on that x .40 formula.

Any opinions on this?

TIA for the feedback

From my notes:

L x W x H X .38 is the formula to use if you like to use a 'full water' amount in your soap.

If you use a more concentrated lye solution, multiply somewhere between by .4 to .45 instead. I know of a soaper on another forum who normally uses a 40% lye concentration and they multiply by .436.

HTH!

IrishLass

Ok, you've peaked my interest. Why the range from .38 to .436? Does it have to do needing more oil to counteract the increased lye; thus preventing a lye heavy soap?

No, it has to do with the fact that you can vary the amount of water added to the lye, yet keep the amounts of oils and lye exactly the same. Soaping with the soapcalc default setting of water as 38% of oils is called "full water", but more experienced soapers express the amount of water as a percent or ratio of the LYE. Many soapers use less than full water for a number of good reasons.

No, it has to do with the fact that you can vary the amount of water added to the lye, yet keep the amounts of oils and lye exactly the same. Soaping with the soapcalc default setting of water as 38% of oils is called "full water", but more experienced soapers express the amount of water as a percent or ratio of the LYE. Many soapers use less than full water for a number of good reasons.

This is where you lose me. If the formula is for determining the amount of oils you would use in a mold, wouldn't changing the last variable (.40, .436, .38, etc.) change the amount of oil you would end up with rather than the amount of water?

I understand that changing the lye concentration, water as percent of oils or water:lye ratio in soapcalc will leave the amount of lye and oil the same. However, the L x W x Height of Pour x ._ _ is used to initially determine the amount of oils you need, correct? So, by changing the . _ _ number, you are changing the amount of oils in your recipe prior to determining the amount of lye you will need to saponify "x" amount of oils.

I'm confusing myself.

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I'm probably the last person who should talk about this, since it is a math issue, so I am sure that I am misunderstanding it from the get-go. But it seems to me as if the percentage default just varies based on whatever water amount/% it is that calculator designer assumes most people use. So the first one in Gigi's initial posts (40%) assumes that most people will discount water a bit and have more remaining space in the mold for the oil/lye combo (they don't address the lye/oil ratio b/c it depends on your personal SF% needs). The second (39%) assumes that people will use more water so have less remaining space for the oil/lye combo in the mold. Not sure if that makes sense, or if I am repeating what has already been said (and less clearly

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To my tiny mind (L X W X H) X .40 (range .38- .45) just says that oils are around 40% of the volume of the whole recipe, or slightly less .38 assuming that you are using full water. LxWXH = total volume of the soap batter

Think of a 1000 g recipe that assumes that 40% of recipe is oils (400 g) and 60% or 600 g will be the lye and the water. If you lowered the water by, say, 50 g, then the lye and water would be (lets pretend) 550 g or 55% and then the oils would be a larger percentage of the whole recipe, around 45%. I know these numbers arent exact, but it helps my tiny mind.

Think about it this way. Lets say youre making a batch of castile:

If you use full water (38% of oil) and 5% superfat, to get 16 oz of total soap, you would need ~ 0.7 lb of oils.

However,

If you used a 40% solution of lye in water, you would need ~0.8 lbs of oil to fill the same 16 oz mold.

Thus, if your volume is 16 oz then your oil amount will cange depending on how much water is used.

To my tiny mind (L X W X H) X .40 (range .38- .45) just says that oils are around 40% of the volume of the whole recipe, or slightly less .38 assuming that you are using full water. LxWXH = total volume of the soap batter

Think of a 1000 g recipe that assumes that 40% of recipe is oils (400 g) and 60% or 600 g will be the lye and the water. If you lowered the water by, say, 50 g, then the lye and water would be (lets pretend) 550 g or 55% and then the oils would be a larger percentage of the whole recipe, around 45%. I know these numbers arent exact, but it helps my tiny mind.

Our tiny minds must work on the same wavelength because that description makes perfect sense. Thanks!

Think about it this way. Lets say youre making a batch of castile:

If you use full water (38% of oil) and 5% superfat, to get 16 oz of total soap, you would need ~ 0.7 lb of oils.

However,

If you used a 40% solution of lye in water, you would need ~0.8 lbs of oil to fill the same 16 oz mold.

Thus, if your volume is 16 oz then your oil amount will cange depending on how much water is used.

I think that clarifies things. The initial calculation (LxWxHx.40) gives you an initial volume of oils supposing that you are working at full water. However, that volume can/will change if you increase your lye concentration. Correct?

Edit: You people are going to drag me "question by question" into learning the "hows and whys" instead of just accepting "standard protocol", even if my lazy behind was perfectly happy with accepting protocol before I found this site. lol

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Sorry to burst bubbles, but the 0.4 is for imperial and about 0.7 is for metric - it doesn't relate directly to a water amount:

-------------------------
I am completely ignorant when it comes to ounces and inches, so I did the math to figure out what it would be in cm and grams.

Take the volume in cubic cm (Length x Width x Height).
Divide that by 2,54^3 (which is 2,54 x 2,54 x 2,54) = 16,39 (to get the cubic cm into cubic inches).
And multiply by 28,35 to convert that into ounces.
Then multiply by the 0,4.

So it's:
(L x W x H) / 16,39 x 28,35 x 0,4

Which is the same as :
(L x W x H) x 0,692

That's for the metric users.

Please note: I have not tested this formula so use at your own risk! Althouth the link given by TopCat http://www.smellychicksonline.com/2008/ ... your-mold/ gives 0,657 for metric users... I don't know where it comes from but it is very close to what I found.

-------------------------

For what it's worth, here is the source of what's in my notes: http://www.thedishforum.com/forum/i...-really-dumb-question/?p=2629990#entry2629990 The thread in the link also includes how to figure it out in metric. Just look for JM Dault's posts. It's still morning and my mind may be a little sleep befuddled, but I believe what Effy just wrote is the same as what JM Dault writes in the provided link. JM Dault also gives an explanation in the thread of how she came to her figures.

IrishLass

Ok so my follow-up question is -

If the soapcalc uses 38% as it's default, based on my formula, should I be multiplying the volume by .38? Or instead, adjusting that soapcalc default to .40?

Oh good point EG - I was just thinking about pure volume, which makes lots more sense in metric.

Gigi - remember that soapcalc uses that default 38% as WATER percent of OILS (many people use the other options for concentration or ratio of water to lye). The volume estimate of a mold is for amount of OILS in a recipe. You're mixing the two up.

Just use volume x .4 equals the OUNCES of OILS in your recipe for now. Plug that into soap calc for the total weight of your soap. Take notes and tweak as you learn more. I always make a bit extra and have a small mold standing by when Im using a new mold.

Oh good point EG - I was just thinking about pure volume, which makes lots more sense in metric.

Gigi - remember that soapcalc uses that default 38% as WATER percent of OILS (many people use the other options for concentration or ratio of water to lye). The volume estimate of a mold is for amount of OILS in a recipe. You're mixing the two up.

Just use volume x .4 equals the OUNCES of OILS in your recipe for now. Plug that into soap calc for the total weight of your soap. Take notes and tweak as you learn more. I always make a bit extra and have a small mold standing by when Im using a new mold.

Seawolf awesome, I did it right... I was worried I was making a mistake ... thanks

Oh good point EG - I was just thinking about pure volume, which makes lots more sense in metric.

Gigi - remember that soapcalc uses that default 38% as WATER percent of OILS (many people use the other options for concentration or ratio of water to lye). The volume estimate of a mold is for amount of OILS in a recipe. You're mixing the two up.

Just use volume x .4 equals the OUNCES of OILS in your recipe for now. Plug that into soap calc for the total weight of your soap. Take notes and tweak as you learn more. I always make a bit extra and have a small mold standing by when Im using a new mold.

So, that took me back to my previous post. LxWXHx.40 is for volume (Standard measurements, not Metric) and you don't want to mess with that.

Lye concentration, Water as a percent of oil and/or Water:lye ratio are numbers that you can change in order to get a faster/slower trace, if your FO is an accelerator, if you want to quicken the time it takes for your water to evaporate (does not speed up "cure" time though), etc. etc.

Correct?

Ahem..Ill just stick to my full water lol

Carry on

Lmfao Jstar

In imperial measurments: LxWxH=volume of the mold in cubic inches. Cubic inches x 0.55 = fluid ounces. The reason we multiply by 0.4 is to both convert to weight as well as to account for the water in the recipe to fill the volume of the mold. In other words, about 72% of the volume of your mold will be taken up by oils and the remaining 28% will be water and lye. The hard part is figuring out volume then converting it to weights then converting it to oils and water. Yes, your total volume will vary a bit depending on your lye concentration, but this is a good basic starting point.

Metric is much easier. LxWxH= volume in cubic centimeters (make sure you measure in centimeters!), and metric converts quite nicely to both fluid measurements and weights, so all you have to do is multiply cubic centimeters by .7 to get your oil amount (remember that 72% give-or-take that is the oil portion of your recipe? That's what this is).

Have NO idea if that helped at all, but there ya go.

In imperial measurments: LxWxH=volume of the mold in cubic inches. Cubic inches x 0.55 = fluid ounces. The reason we multiply by 0.4 is to both convert to weight as well as to account for the water in the recipe to fill the volume of the mold. In other words, about 72% of the volume of your mold will be taken up by oils and the remaining 28% will be water and lye. The hard part is figuring out volume then converting it to weights then converting it to oils and water. Yes, your total volume will vary a bit depending on your lye concentration, but this is a good basic starting point.

Metric is much easier. LxWxH= volume in cubic centimeters (make sure you measure in centimeters!), and metric converts quite nicely to both fluid measurements and weights, so all you have to do is multiply cubic centimeters by .7 to get your oil amount (remember that 72% give-or-take that is the oil portion of your recipe? That's what this is).

Have NO idea if that helped at all, but there ya go.

new12soap that actually helped quite a bit thanks

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