Calculating soap weight for molds

[FrayGrants]

I bought a few molds of various shapes and sizes for individual bars, and I'm curious how to go about calculating how much soap by weight would be needed to fill them. I could obviously shoot for less than needed and partially fill a cavity with any leftover, or simply chuck it if it isn't enough to fill a cavity at least halfway. I'm just curious if there is a way to calculate it exactly, or close to it.

Can I fill the cavities with water and assume the ounces in volume would be close to the final soap weight? Also I am making salt bars, and I am curious as to how much the salt will offset the volume, but let's not factor that in. I'm open to any and all suggestions, even they are to just wing it and find out. Thanks in advance for any and all replies!

 

[Zany_in_CO]

Mold descriptions should say how much soap the mold holds. For example, my WSP 1501 Loaf Mold holds 40-44 oz. of soap. To find out the amount of oils needed to make 40-44 oz. of soap, ! use a factor of 1.37:

40 oz soap / by 1.37 = 29+ oz oils
44 oz soap / by 1.37 = 32+ oz oils
From experience, I learned that 30 oz. oils makes 40 oz. soap that fills the mold even with the top. 32 oz. oils gives me a little extra to make small sample size disks that I pour into 1 oz. or 2 oz. circle molds.

For my 6 round cavity mold, each holds 5 oz. X 6 cavities = 30 oz soap to fill all 6 cavities.
30 oz soap / by 1.37 = 22 oz oils (rounded up)

ETA: For wooden slab molds of any dimension and round cylinder molds you can go to:

SBM Soapmaking Calculator and Recipe Resizer

First enter any formula and hit Calculate Results. On the next page look below the calculations to find where you can resize the recipe to fit your mold by entering the Height, Weight and Depth. Easy peasy.


HTH

 

[lsg]

Try this link. Volume of mold

 

[CpnDouchette]

Lisa from I Dream in Soap has a wonderful guide to making the right amount of soap for your mould.

 

[FrayGrants]

Mold descriptions should say how much soap the mold holds. For example, my WSP 1501 Loaf Mold holds 40-44 oz. of soap. To find out the amount of oils needed to make 40-44 oz. of soap, ! use a factor of 1.37:

40 oz soap / by 1.37 = 29+ oz oils
44 oz soap / by 1.37 = 32+ oz oils

WOW!!! That’s so helpful, thank you so much! 29 oz. of oil is exactly how much I use in my 40 oz. molds. I put water in my cavity molds and weighed it and a fluid oz. weighs exactly an ounce, so now all I have to do is divide by 1.37 and I’ll know how much batter to make.

I will have an extra mold prepared in case there is a small amount of extra batter. Thanks again Zany!!!

 

[Zany_in_CO]

Thanks again Zany!!!

You're welcome, Fray!

 

[Savage Daughter]

I will have an extra mold prepared in case there is a small amount of extra batter. Thanks again Zany!!!

Yes, always have an extra mold standing by. Sometimes the tail end of the batch you're pouring will thicken up & having to rifle through a bin of molds (that would be me) while that is happening, then getting back to your soap & having to plop the tailings into those cavities can really suck. They rarely turn out smoothly, especially on their sides, even after slamming them down several times.

RE: slamming cavity molds down to remove air bubbles > you might want to put those puppies on a firm wooden cutting board or something of the type & then slam that down on a towel, because slamming down floppy cavity molds without support can turn into a gong-show very quickly

Ask me how I know