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How to “handle” water evaporation during phase heating
Hello.
A few questions about this, please:
-1- When we see in a formulary a recipe calling for, say, 50g of water as part of a phase that will be heated, is the assumption that we *start* with 50g, and that this 50g will be reduced a fair amount as a result of the heating, with the true amount incorporated likely being closer to 45g? Or is the recipe truly calling for 50g of water to be incorporated?
-2- Assuming the recipe is truly calling for 50g of water to be incorporated, how does one accurately account for this (i.e., “pad” it) so that the heated water amount will equal 50g? Is one meant to re-weigh the beakers just before blending the phases (adding extra water to replace that lost to evaporation)?
Thank you.
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11 Replies
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The 50g…is the ending amount of water. Many start with about 10% extra water, as that is an average amount lost.
I weigh my beakers, and of course know the formula weight, so post emulsion, I toss it back on the scale….top off the water, and emulsify once again. Since I start with 10% extra, very little is added at that point. So you only need to weigh the beaker that both phases end up in.
Just remember….a formula always equals 100%. Never 100% - evaporation.
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This is how I AVOID evaporative loss. I use canning jars with a hole drilled into the lids so I can put my thermometers into the phases to monitor their temperature during the heating phase. I do NOT lose any appreciable water through evaporation this way. Of course, this only works if you’re small-scale, like I am. The jars, lids, thermometers and the pincers (orange handles) are all of course cleaned & well-spritzed with 70% alcohol before I weigh my ingredients into them &/or before I start the heating ceremony. -
I either add around 10% more water when weighing or add more water to top up after cool down before preservatives.
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I always pour my heated water into a pyrex measuring cup to re-measure the amount of water lost and then add the amount of water needed. (make sure your pyrex measuring cup is pre-heated to prevent breakage when the hot water is poured into a cold pyrex measuring cup)
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If I make a small batch, I heat up the water phase and non heat sensitive ingredients (like emulsifying agents) in a borosilicate measuring cylinder. That way, I can easily see if there were any major water losses. I’ve done this in the microwave several times with success. The water heats up fast and is not evaporating during a long time.
I really like Margaret’s suggestion. Do the lids get hot?
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When I make batches, to prevent water loss I put saran wrap over the top and cover the gap with aluminum foil. That way I can easily add ingredients without it being uncovered for very long.
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suswang8 said:Hello.
A few questions about this, please:
-1- When we see in a formulary a recipe calling for, say, 50g of water as part of a phase that will be heated, is the assumption that we *start* with 50g, and that this 50g will be reduced a fair amount as a result of the heating, with the true amount incorporated likely being closer to 45g? Or is the recipe truly calling for 50g of water to be incorporated?
-2- Assuming the recipe is truly calling for 50g of water to be incorporated, how does one accurately account for this (i.e., “pad” it) so that the heated water amount will equal 50g? Is one meant to re-weigh the beakers just before blending the phases (adding extra water to replace that lost to evaporation)?
Thank you.
There is a rule, although i am not sure if it’s correct, but it says that you should compensate the evaporated water in advance, and that’s about 10% of the overall water size. Just keep in mind that the water keep evaporates during the cool down as well, so in general you can estimate the water loss only after it cools completely, i.e. arround 30 degrees. So, if your formula says 50g. of water, you should add 55g.
You can’t find in advance how much exactly water will evaporate, because this process is deppendant of many other conditions.The adding of a water into a cool emulsion makes no sense, and sounds like absurd! When the emulsion is cool, the emulsification is already completed, so this additional water can’t be incorporated in the emulsion anymore. -
I was quite pleased with the lids I made for my beakers. Until recently, I was just letting up 15- 20% of the water evaporate off like a chump. Now it’s down to about 7% loss which I add in as extra water at the beginning. I weigh the final cream after cooling down and knowing how much the beaker weighs, I can tell if I added in the right amount or not (and adjust again for next time if needed).
The lid is one of these: https://www.amazon.co.uk/Munchkin-Miracle-Lids-Styles-Multicoloured/dp/B07QKDP8F6 and is silicone and flexible so it’s easy to cut into, to twist/bend to put on, lift up etc. In the pic, it’s on top of a 250ml beaker. I can just lift it without taking it off completely when I want to check the temperature.
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Add 5% additional water pre-heating and then put a watchglass on the top of the beaker during heating and processing.
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I guess the best way would be a reflux setup with overhead stirring and cooling condensers. I have to mirror the 10% loss figures, I get the same thing.
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Quite honestly, this is not as big an issue as it’s being made out to be … in a cosmetic product, being off by a couple of percent is not really that big a deal imho … remember, you’re heating up to 70C to 75C, so you will get some water loss, but it’s not like you’re heating up to near the boiling point of water.
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