Soap bar size and weight.. Calculation advice needed

[isha]

Hi all.,
I've made couple of batches in various mould. I have one slab mould.. Silicon 12" *3.5"*4 "
I usually fill it full and then use my multi wire cutter to cut even bars.( got it made from a local carpenter)

Now I also got a wooden mould made. Tats 12" * 4"*4"
So I got a 12" long slab ... But just using the cutter makes the soap looks like a square box.. A big one [emoji16] [emoji16] [emoji16]

Now how do I. Cut them so I get 100gms as each bar.. I'm very bad in math.. My wire cutter is 3/4" wide.

Also. Does the weight of the bar alter after curing??
How to determine the size of bar. If I want the end product to weigh 100gms per bar??

 

[DeeAnna]

The answers you want are going to be based on trial and error using your recipes, your molds, and your cutter.

First thing, soap loses weight during the cure. So if you want your bars to weigh 100 grams after cure, you need to cut them so they're heavier at first to allow for that weight loss. Have you weighed your bars to know how much water they lose over time?

Another thing is soap making is an inexact science. You won't be able to absolutely get all bars to weigh exactly 100 grams, so you need to plan for that. If you have a multi-wire cutter, then the bar width and thickness are fixed for a given mold. So the only variable you can change is the height. Have you figured out how the weight varies with height?

And lastly, the bar size that will work for my soap may not work for your soap because the bar weight is dependent on the recipe. Your recipes are going to be different than mine -- more or less water, different additives, etc. All this will affect the weight of the bars.

Experiment and see what works.

 

[isha]

Thanks deeanna..
I've weighed my fresh cut bars and cured once.. But as u said the weight varies for each type.. I guess the additives. Make huge difference..

 

[penelopejane]

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

This may also help. You just have to adjust for height to work out the weight.
My bars lose about 5% in all dimensions after cure.

 

[isha]

Thanks. I'm. More concerned about cutting the bars to the right size.. I've learnt how to fill my mould...

 

[penelopejane]

Thanks. I'm. More concerned about cutting the bars to the right size.. I've learnt how to fill my mould...

Your bars should be the same thickness. Your mold size varies but The only adjustment you have is the amount of batter you put in.
Test each mold until you work out the amount of batter for each recipe to get to the desired bar weight after 3 months.
Do not fill your mold full.

 

[SaltedFig]

If you're going to use a standard size cutter (at 3/4"), in a mold that is 4" wide, then the only thing that you have left to adjust is the pour height, not the cut.

Filling the mold to the brim and then trying to cut uniform weight bars from it would be a lot of effort for not a lot of gain. This could lead to some interesting angles in all bars of your soap and may explain why people are suggesting you adjust your pour height (instead of filling to the brim and trying to work out the cuts).

Edited bit:
You can cut 16 bars with your 3/4" multi-bar cutter, from your 12" log. What you want to work out is how high to pour your particular recipe to make each bar cure out to just over 100 grams.

If you use the conversion rate you posted as working for your specific recipe, and then use your previous shrinkage test as your rough percentage reduction in weight, you should be able to calculate a mold pour height for your personal recipe.

Testing will have to be done for your specific formula. YMMV

 

[isha]

I will give it a try.. As someone said 5% is the reduction in weight..
I haven't been wise enough to measure the weights well.. As I got the cutter very recently.. I will weight them from now on though..

What would be a decent size of bar??
My mould gives me 12"*4" *4"
So if I'm cutting with wire cutter at 3/4" width.. I get 16 bars.. Tats 4"* 4" Those are really huge squares..
So I'm trying to figure out how much less shall I pour..
1" or 1.5"

I would like to make it much decent looking and later focus in weight.. I guess tats a better at o go about it..