I thought Great Britain used Imperial measures for a lot of things?
The UK uses metric for certain things and Imperial for others. Their Imperial system is not the same as the US customary system though. For example, an Imperial pint of beer is 20 Imperial oz, but their ounces are slightly smaller than US ounces, so if you convert it to US ounces, you around 19.2152 US oz per Imperial pint. Beer must be sold in pubs in Imperial Ounces, so that is a plus.
35.19508 Imperial Ounces per liter
33.814023 US Ounces per liter
You will find over there that distances between cities on the highway are measured in miles, the distance to an exit that is fairly close is measured in yards, but the clearances of the bridges are measured in meters.
So, when you see a car over there advertised as getting a certain mpg and wonder why the same exact car in the US gets worse gas mileage, you have to remember that their gallons are larger, thus the vehicle can go further on their gallon than it can on the US gallon.
As an engineer, I can use metric, US customary, or even Imperial if necessary. Depending upon what I'm doing, I'll use what is most convenient to use.
I think that some people who have trouble with mold volumes are failing to understand densities of the various ingredients and they might also not know that the US ounce (volume) is not the same as the US ounce (weight) even for water. In the metric system, *originally*, 1 kg *was* defined as 1 liter of water. Currently, it's defined as:
"The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015×10−34 when expressed in the unit J⋅s, which is equal to kg⋅m2⋅s−1, where the
metre and the
second are defined in terms of c and Δ
νCs."
https://en.wikipedia.org/wiki/Kilogram#Definition
Not exactly something that you can do in your home lab, but it's within 30 ppm of the original definition, so we can get away with the 1 ml = 1 gram of water approximation.
The difference between dry and liquid measurements in the US can get confusing since many suppliers of products do not necessarily state whether it is a dry or liquid measurement that their product is sold in. Sometimes oils are sold by the liquid gallons and sometimes by pounds.
1 dry gallon = 268.8025 cu-in = 4404.883771 ml
1 fluid gallon = 231 cu-in = 3785.411784 ml
Also, we need to remember that even the rough figure of 1 g = 1 ml of water is assuming that the water is pure and at it's maximum density (approximately 4C). Most other things that go into these soap recipes have their stated densities at a different temperature. For example, soybean oil might be 0.9193 g/ml at 75F, but it is 0.9023 g/ml at 120F and 0.8615 g/ml at 230F.
https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1016&context=chemeng_biomaterials
So, for me at least, I would use the metric system for any sort of recipe where the measurements needed to be critical. That way, you only need to convert the size of your mold from inches to cm (1 inch = 2.54 cm *exactly*). Of course, this is assuming that you have a scale that measures in grams.
oops, hope it helps someone down the line
That is my view also. There are some people who are rather anal-retentive about posting to old threads and think that you should start a new thread. I disagree with this since I find it more convenient for everything to be in one place than possibly in 20 different threads which are often repeating stuff that was in the other threads.
Unlike many people who are on this forum or on the various YouTube channels about soap making, I have no desire to turn it into a commercial endeavor. I'm doing it so that I can get a use out of some of my older used fry oil instead of just mixing it with my dogs' dry dog food (they really like it though). Plus, I want to be able to create a mechanic's soap that is ever better than the Lava brand. Instead of pumice, I'm thinking of using aluminum oxide blast media. No fancy fragrances, just basic soap that will clean grease off my hands after I've been working on something in my workshop.
