DIfference in calculators...

[Grannyscandles]

I have been making soap since 2003 but have been in hiatus since my son was born in 2007. Pre-Isaac I used Summer Bee Meadow's lye calculator. I noticed that it is never mentioned here and others seem to reign as the GO TO calcs.

I put a recipe in both this morning and got quite different water amounts. One was 17.6 ounces. The other was 20 ounces. Any idea why this is?

[Kitn]

I use soapmaker3 , I really don't know why the difference, most people use soap calc, I believe.

[topofmurrayhill]

Since water doesn't take part in the chemical reaction, there's not truly a "correct" amount. Different calculators take different approaches.

The amount of water makes a difference in how fast the batch traces and saponifies, how likely it is to gel, and how long it needs to dry before you can use it. For those reasons you could decide how much water you want to use, either in general or in a particular batch.

Some calculators let you control the water calculation. One of them suggests a range of amounts you can use. You can even do your own calculation separately. Only the oil and NaOH amounts have to match what a calculator tells you, but the water can vary.

SoapCalc starts you off with a fairly high water amount, but you can bump it down. It will do the figuring for you any way you want. The best way might be to click where it says "Lye Concentration" and type in a percentage. A lot of soapers think about water in terms of lye concentration.

25% lye concentration would be very high water and is pretty much the most anyone uses. 50% lye concentration would be very low water and is pretty much the least anyone uses (it gets hard to dissolve the NaOH). 33% is a popular medium number. If that traces too fast for you, you can try something like 28 to 30%.

[Grannyscandles]

Thanks again top!

[chuck_35550]

I believe that 38% is the default on water as percent of oils on calc. I use a lye concentration of 35% and Miller Soap recommends using 2:1 water/lye ratio. There are a lot of variables and you really have to pay attention to whatever calculator you are using as to those variables. HTH.

Steve

[topofmurrayhill]

As an afterthought, I think it might be important to point out that there are two different ways that calculators figure water, and two different ways to think about it. Both are expressed as percentages, but you don't want to get confused between the two.

Water is sometimes figured as percentage of oil weight. In this calculation, a higher percentage means more water. If you don't change anything, SoapCalc uses this method and defaults to water as 38% of oil weight, as Steve pointed out. If your oils weighed 100 oz, it would tell you to add 38 oz water.

The other way of thinking about it is in terms of how much water is used to dissolve the NaOH (in other words, the concentration of the lye). This is expressed as the percentage of NaOH in the lye by weight--so a higher percentage means less water. A 50% lye concentration is half NaOH and half water. A 25% lye concentration is one quarter NaOH and three quarters water.

The trend, especially among more serious soapers, is towards using lye concentration. There are some advantages to it, such as making it easier to use a standard lye instead of having to mix it differently for each batch.