Precision Measurements

[marilynmac]

I just finished my ninth batch of CP soap. I have a question about measurements. When I started, everything I read said it was very important to measure very carefully, use grams instead of oz for more precision. The implication was that you would have a chemical weapon on your hands if you weren't very very careful.

As I read more, I see that most recipes have superfatting built in. Soapcalc has a superfat % you can adjust.

How important are these precise measurements? If you have a few extra grams of this or that oil in the 1200 g of fat in your recipe, isn't that just adjusting the superfat level, which is arbitrary to start with?

Or is it only to make sure you can duplicate the soap. For that matter, does a 1-2% error even make a difference in the soap?

 

[Dorymae]

A one - two percent difference can make a big difference in soap. It may not make a huge difference if you are comparing a coconut oil soap with 18 percent superfat or 20 percent superfat. However if you were making a soap with a 3 percent superfat and made a mistake in your oils - or worse if you made a couple mistakes with different oils you could potentially have a disaster. ( no chemical meltdown or anything - just a soaping disaster)

You should always try to be as accurate as you can - even if it is just so you can reproduce the same recipe. I have found though, that when someone starts out estimating then never do go back to accuracy until they do have a huge problem. (Notice I didn't say if they have, but until they have, because like never changing a tire - it's a matter of when - not if).

 

[marilynmac]

Thanks, Dorymae. It was slowly dawning on me ... I realize that if you start under-measuring, that's an easy disaster. But, otherwise, it will make soap.

I understand the consistency bit, and that's what I'm trying for, but fiddling with that last 1/2 gram of coconut oil was driving me nuts.

 

[shunt2011]

I try to be as accurate as possible but if anything I sometimes get a bit more .5-1 grams of this or that. I do however make sure my lye is spot on. I would rather have a bit higher superfat than lower. So, just be as careful as possible. I'm usually spot on. Make sure your scale is calibrated and accurate too.

 

[coffeetime]

I wouldn't (and don't) bother measuring half grams. I set my calculator to whole grams and away I go. Works fine. I typically use a 6% superfat.

 

[wetshavingproducts]

1 gram out of 1,000 is .001 or .1% or 1/1,000th of a difference.

1 gram out of 100 is 1%, and 1 gram out of 10 is a disaster.

 

[Susie]

I use ounces and tenths for everything. If I need to round, I go up on oils and down on lye.

 

[The Efficacious Gentleman]

Like Susie, if I am not spot on then I go heavy on the oils and light on the lye, effectively increasing my superfat.

That said, I have a measure that goes to 0.0 grams and there is no feeling like getting it spot on target

 

[marilynmac]

That said, I have a measure that goes to 0.0 grams and there is no feeling like getting it spot on target

Spot on target .. that's my problem, spending too much time trying to acheive that. Now I know I can call it "superfatting" and get on with it.

 

[DeeAnna]

I think there's a point in any art or craft about understanding what is "good enough" and what is "not good enough". Lee alluded to that (Post #6).

If I'm weighing essential oils and need precision and accuracy, I break out my fancy lab-grade scale that weighs to 1/100 g. If I'm weighing soap ingredients (water, lye, fats) I weigh to whole grams.

As a former college instructor, I have learned you can't throw everything at a beginner. Their eyes glaze over, enthusiasm melts away, and active learning shuts down. I learned to teach clear, hard-and-fast rules to beginners to ensure they stay relatively safe and on-track, and ensure they have success. I introduce the shades of gray and the exceptions-to-the-rule later on after students have the basics down.

That's why I think a lot of advice to beginning soapers is couched in terms of black-and-white rules. It's only after some experience that soapers are in a position to learn when the rules are to be followed to the letter and when the rules can be bent.

 

[marilynmac]

It's only after some experience that soapers are in a position to learn when the rules are to be followed to the letter and when the rules can be bent.

OMG, I have learned something! :grin: