How to figure how much oil for mold.

[Soapmaker Man]

I did soap maker mans calculation for my box. Guess what??? It was exactly right. This is only my second batch of CP, thank you so much soap maker man. You rock!!!!

You're quite welcome.

SMM :wink:

 

[Bnky]

I just got a small mold for sample bars and this is just what I needed. I wish I had looked at it before I made my large batches. Great info, Thanks Paul!
Bnky

 

[kslo78]

I just bought a silicon mold for $3 at Marshalls and this post was super helpful. It's a 2.3 lb loaf mold.

 

[Guest]

I hope someone can answer this question. I'm going to make some soap tonight and plan to mix shredded soap pieces into it before molding. This would obviously increase the volume of the batch.
How can I account for this extra soap and figure out what size mold to use?

 

[cwayneu]

I hope someone can answer this question. I'm going to make some soap tonight and plan to mix shredded soap pieces into it before molding. This would obviously increase the volume of the batch.
How can I account for this extra soap and figure out what size mold to use?

First off, you need to know the total batch size by finding the mold volume and multiply by .4, as this thread explained. For example, let's say you have a slab mold 10" by 10 1/2", and you pour your bars 1" thick.

You take (L X W X H)

10 X 10.5 X 1 = 105, then 105 X .40 =42 oz So your total batch size is 42 oz.

However, since you are replacing some of the batch total with already made soap (your shreds), you need to reduce the batch total by the amount of shreds you are adding. The percentage of shreds is actually your choice, but we have found that 20% is just right for us. Whatever number you pick, the next step is to determine ounces of the shreds part and the batter part.

Following on with the 42 oz batch example, we want 20% shreds and 80% new batter.

Shreds = 42 X 20% ( or .2 ) = 8.4 oz
Batter = 42 X 80% ( or .8 ) = 33.6 oz

So you need to weigh out 8.4 oz of shreds, and use 33.6 oz as your batch size in soapcalc to figure out your oils, lye, etc.

Then you make your 33.6 oz batch as normal, but just before you pour into the mold you stir in your 8.4 oz of shreds.

Hope this helps.

 

[Soaps House]

All you have to do is find the area out and then multiply it by .4. It doesn't matter is the mold is square, round, or a triangle. Unfortunately I don't remember the formulas for round or triangle, but that is why we have Google right?

John

 

[cwayneu]

All you have to do is find the area out and then multiply it by .4. It doesn't matter is the mold is square, round, or a triangle. Unfortunately I don't remember the formulas for round or triangle, but that is why we have Google right?

John

It's actually .4 times the mold volume (in cubic inches), not just the area (square inches) to get the batch size in ounces.

 

[Soaps House]

It's actually .4 times the mold volume (in cubic inches), not just the area (square inches) to get the batch size in ounces.

Your right...just a little typo, thanks.

John

 

[chandler Trev]

I had built a mold and wondered this very topic. How much oil to fill it. I found you formula and walla, filled right to the top. Thank you

 

[cwayneu]

I had built a mold and wondered this very topic. How much oil to fill it. I found you formula and walla, filled right to the top. Thank you

That's great. Folks should keep in mind that you don't always use the complete mold volume times .4 to figure your batch size.

This may be obvious, but for example we make all of our rectangular bars 3 1/2" by 2 1/2" by 1" thick. We have a log mold that is 3 1/2" wide by 30" long by 3" deep. We normally want the batter only 1" thick for face up bars so we can decorate. The bars come out side by side lying flat face up. That means we can make 12 bars (2 1/2" wide X 12 bars = the 30" length) by pouring the batter 1" thick. So we calculate 3.5 X 30 X 1 X .4 to get a batch size of 42 oz. However, we can also make 30 bars, on their side edge, from the same mold by pouring batter 2 1/2" deep. This means our batch size would be 3.5 X 30 X 2.5 X .4 or 105 oz. Hope this makes sense.

 

[cwayneu]

One final update for mold trays

One other issue you may run it to is wanting to use a mold tray of some kind, like a silicone muffin pan, where it may tell you the total volume in ounces. We have a tray of hearts that says it holds 6.5 ounces. It won't be exact based on water weights, but 1 ounce of water converts to 1.8 cubic inches of water. So if the tray holds 6.5 ounces, that is 6.5 X 1.8 = 11.7 cubic inches.

Since that batch formula is always the mold volume in cubic inches times .4 to give you batch oil/fat ounces, then the tray batch size should be 11.7 X .4 = 4.68 (or about 4.7 oz. to put into soapcalc). This makes sense because you will be adding just under 2 oz. of lye water back into the oils/fats, which gets us back to about the 6.5 ounce tray size.

I found a free calculator some time ago that converts just about any units to about any units you want. In this case I used the volume tab to get the 1 oz. = 1.8 cubic inches. You can download it at

http://joshmadison.com/software/convert-for-windows/

Finally, if you don't know the volume or ounces of some weird shaped tray or mold, you can always put it on your scale, tare it out, and fill it with water. Then take those ounces times 1.8 times .4, like the above example. That's the number you put in soapcalc.

Happy soaping...

 

[Fuzled]

I had built a mold and wondered this very topic. How much oil to fill it. I found you formula and walla, filled right to the top. Thank you

That's great. Folks should keep in mind that you don't always use the complete mold volume times .4 to figure your batch size.

This may be obvious, but for example we make all of our rectangular bars 3 1/2" by 2 1/2" by 1" thick. We have a log mold that is 3 1/2" wide by 30" long by 3" deep. We normally want the batter only 1" thick for face up bars so we can decorate. The bars come out side by side lying flat face up. That means we can make 12 bars (2 1/2" wide X 12 bars = the 30" length) by pouring the batter 1" thick. So we calculate 3.5 X 30 X 1 X .4 to get a batch size of 42 oz. However, we can also make 30 bars, on their side edge, from the same mold by pouring batter 2 1/2" deep. This means our batch size would be 3.5 X 30 X 2.5 X .4 or 105 oz. Hope this makes sense.

So this means that I don't have to fill my mold to the very top? I've been reading this and using the mold size calc online, but have been wondering if it's ok NOT to fill my mold all the way up..

 

[cwayneu]

So this means that I don't have to fill my mold to the very top? I've been reading this and using the mold size calc online, but have been wondering if it's ok NOT to fill my mold all the way up..

Exactly. You only make the soap as thick as you want, and the calculation has to be based on the thickness you want, not the absolute maximum limit of your mold.

 

[Fuzled]

What am I doing wrong to understand this? Every time I try to do my own calculations I end up with too much total liquid (I think) for the entire mold..no matter what mold size I try and run these with I end up with the problem listed below..

Hoping some one can set me straight.. here's my math:

I have a 2lb (per the manufacture) mold that measures inside dimensions:
3.5in w x 9in l x 2.5 h= 78.75 cu in volume

78.75 x .4=31.5 oz of oils per the calculation, correct?

Here's where I get confused:

2lbs mold =32oz

When I run oil amt thru Soap Calc (ex. is 100% tallow) it says:

31.5 oz oils + 4.2oz lye +11.97 oz Water. This equals 47.67 oz of total liquid.

This is way too much for my 32 oz mold, right?

It seems everyone uses this formula, so I must be not understanding something.. Can anyone help me?

EDIT: I think I know where I'm screwing up. The 2.5in is the pour line, the 2lb listing is actually the amt of oils. So recalculating actual height of the mold is 3.5, giving 110.25 cu in which = 61 fl oz. This would account for the oil and lye water

 

[cwayneu]

Fuzled, not sure. The 2 lb label on your mold is confusing. Based on the conversion of 1 oz of water = 1.8 cubic inches, that says that 32 oz (2 lbs) times 1.8 = 57.6 cubic inches. Yet your 3.5 X 9 X 2.5 = 78.75 cubic inches. If we reverse that to find ounces we get 78.75 / 1.8 = 43.75 ounces, or 2.7 lbs. So I don't know what the 2 lb label refers to, since it is almost 3 pounds.

I have checked the 1 ounce = 1.8 cubic inces with one of my molds and it holds pretty true. I have a 3.5" by 8" by 2.5" deep mold (= 70 cubic inces). It takes exactly 39 ounces of water (on my scale) to fill it to the top. And to check I took 39 ounces X 1.8 = 70.2 cubic inches (pretty darn close). So again, the 2 lb label on your mold seems to be bogus.

I do always keep a single bar plastic mold handy, in case I do have batter left over, so I can dump it in there.

 

[Korgan]

My ol' spreadsheet

Hey guys,

Few years ago, I wrote a very useful spreadsheet. Now, I have no idea where you got the 0.4. But I think some people were saying it worked for them so I won't criticise too quickly.

What I do know is that this spreadsheet I made calculates the density of the soap of any recipe I give it. So, I have my container, I fill it with water and then I weigh that water. Then I enter that into the spreadsheet as well as the recipe. The spreadsheet then calculates the density of that soap and scales the recipe automatically to fit into the given container.

Since the density of each oil is different, and most recipes have different oils, the density of each soap is always different. So you can't give one number, like 0.4, and have it be correct all the time.

Also, the spreadsheet automatically costs each ingredient in the recipe, gives me a total cost of the block of soap, and figures out a selling cost of the total block and each 100g bar. Very handy! :wink:

Anyway, this is my first post in this forum and hope to have fun while I'm here.

Also, what's with the near-impossible capcha codes on this forum? Ridiculous.

 

[IanT]

That sounds so cool!!

As far as the codes...yeah they are a PAIN in the rear..but they only last for the first 10 or 15 posts to make sure youre not a troll or robot or something... I swear it took me like 2 weeks to finally get them to go away and I agree with you 100% they are a pain in the rear for sure!!!

 

[cwayneu]

You are totally correct in that every different recipe will have different densities, therefore different volume weights. It's a good idea, but the .4 is a rule of thumb published by several sources and seems close enough. I have my molds all labeled (like 42 oz. for example). I don't want to re-enter my recipe on every different batch just to be a perfect 1.00" thick. My bars may vary from 0.99" to 1.01", but no one can really tell the difference. If soapcalc did this for you, it would be cool. But like I said, re-entering the recipe into another tool just does not seem worth it. IMHO.

 

[Korgan]

I forgot to mention, my spreadsheet also calculates how much lye is required, so I don't need Soapcalc. :wink:

So as for having to type it into two programs, that's unnecessary. I'm not a fan of any of the soap calculators online.

 

[cwayneu]

I forgot to mention, my spreadsheet also calculates how much lye is required, so I don't need Soapcalc. :wink:

So as for having to type it into two programs, that's unnecessary. I'm not a fan of any of the soap calculators online.

OK, now that's pretty cool. So the next question is, how can we get our hands on your spreadsheet?