# More maths, calculating gross weight (mass)

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#### PerthMobility

##### Well-Known Member
I am confused about how to add up the total of my ingredients in Cold Processing so that I fill a mould but waste as little as possible.

So if I take 1500mls of water and add 650gms of sodium hydroxide do I get 2150 of lye or is some lost through heat?

Then if I then blend 3,700gms of oil and 150gms of essential oil with the lye, do I get a mass of 6,000gms and will this fill a mould with a capacity of 6,000 cubic centimeters?

It seems to me there must be a "rule of thumb" for the percentage of loss that is probably incurred, as I suspect I will finish up with less than 6,000cc.

To be totally sure, you can make some batches and see if it is more or less than what you want. As you say, trying to calculate it won't ever be 100% spot on to the nth decimal point because of evaporation, amounts left in containers/on utensils and so on. Some things are sure - 6kg is far too big a batch for you to be making at this point and 6kg of batter != 6,000 cubic centimeters, as was already explained to you the conversion between weight and volume is only 1:1 with the water. Even a saline solution will not be 1:1 weight:volume. Lye solution is not 1:1, either.

I am confused about how to add up the total of my ingredients in Cold Processing so that I fill a mould but waste as little as possible.

So if I take 1500mls of water and add 650gms of sodium hydroxide do I get 2150 of lye or is some lost through heat?

Then if I then blend 3,700gms of oil and 150gms of essential oil with the lye, do I get a mass of 6,000gms and will this fill a mould with a capacity of 6,000 cubic centimeters?

It seems to me there must be a "rule of thumb" for the percentage of loss that is probably incurred, as I suspect I will finish up with less than 6,000cc.

The rule of thumb In English units is the mold inside dimensions L x W x H x .4 in inches gives you the weight of oils to use in ounces (note this is not the weight of soap).

n. Some things are sure - 6kg is far too big a batch for you to be making at this point and 6kg of batter != 6 said:
Awe, spoil sport. I actually have a 600cc mould which I want to use but got a bit carried away with zeros.

From your response Craig, I gather that there will not be sufficient loss of mass to concern me. So if I have a 600cc mould make a up batch with a gross mass of 600grms and it will be "close". Thanks

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