Does lye water evaporate fast

[EstelleK]

Hi,

I recently started making soaps and I've had a few successful ones except the last two of my batches. My mold holds 42oz so using SoapCalc, I created a recipe with around 42 oz of total soap weight. However, the last two batches did not fill in the mold completely - in fact, about 1/3 of the space is not filled in. I did make sure to not forget any ingredients. Why is this happening? I put the lye water outside for about 2 hours without lid, so did water evaporate from the lye water? (Can so much water evaporate that fast?)

The first failed batch - I tried cutting it after 2 days and it was so crumbly that I couldn't finish cutting. The second failed one - I just made it so planning to cut it in 24 hours.

Here is the recipe I've used:
1.12 oz Castor oil (4%)
2.80 oz Canola oil (10%)
8.40 oz Palm oil (30%)
7.84 oz Coconut oil (28%)
2.24 oz Rice bran oil (8%)
5.60 oz Olive oil (20%)

3.99 oz lye
8.40 oz water
1.40 oz fragrance oil

Thank you in advance!!

 

[DeeAnna]

Room temperature lye solution for making soap will gradually absorb water from the air. You should have more volume not less.

The only situation where a lye solution will lose weight is right after it's made when you can see visible "steam" rising from the mixture. But even then, it shouldn't lose enough water to cause the problem you describe.

My calculations show your batch should weigh a total of 41.8 ounces by weight and occupy a volume of about 73 cubic inches. Using the width and length of your mold in inches, you can calculate how deep this batch will fill your mold.

If your actual batch wasn't anywhere close to that depth, then you mis-measured or your scale is inaccurate or the scale's batteries are dying or you left out an ingredient or something.

 

[earlene]

Did you actually fill the empty mold with water and weight the amount of water that it took to fill the mold to the height you wanted?

Have you made soap with the same recipe in the same mold and had it fill to a higher level before? You mentioned only the last two batches we at a lower level.

If all the soaps were the same recipe and the mold is the same and some filled the mold significantly higher than the last two, then I'd suspect the scale or user error. But if you left something out, I'd also expect lye heavy soap. Have you ZAP tested the last 2 loaves?

 

[EstelleK]

Room temperature lye solution for making soap will gradually absorb water from the air. You should have more volume not less.

The only situation where a lye solution will lose weight is right after it's made when you can see visible "steam" rising from the mixture. But even then, it shouldn't lose enough water to cause the problem you describe.

My calculations show your batch should weigh a total of 41.8 ounces by weight and occupy a volume of about 73 cubic inches. Using the width and length of your mold in inches, you can calculate how deep this batch will fill your mold.

If your actual batch wasn't anywhere close to that depth, then you mis-measured or your scale is inaccurate or the scale's batteries are dying or you left out an ingredient or something.

Hi DeeAnna,
I was aware that the total weight was 41.8 oz, but it didn’t seem anywhere close to that. I took your advice and measured the dimensions to realize that the dimensions given by the seller were wrong Obviously, it holds more than 42 oz as it was advertised. I did use the same mold and was satisfied with the outcome once, but I think it was because I had a different design with top heavily textured. Now that I think about it, that successful one was also a bit shorter than the mold height.

Thank you so much for your help!!!

Did you actually fill the empty mold with water and weight the amount of water that it took to fill the mold to the height you wanted?

Have you made soap with the same recipe in the same mold and had it fill to a higher level before? You mentioned only the last two batches we at a lower level.

If all the soaps were the same recipe and the mold is the same and some filled the mold significantly higher than the last two, then I'd suspect the scale or user error. But if you left something out, I'd also expect lye heavy soap. Have you ZAP tested the last 2 loaves?

Hi earlene,
No, I haven’t tried filling the mold with water. What a clever idea! I thought I’ve studied a lot, but there seems to be a lot more things to learn still.
Thanks to DeeAnna’s advice, I realized that the dimensions of the mold provided by the seller were inaccurate; thus, the total weight it can hold is also inaccurate.

Thank you so much !!

 

[DeeAnna]

The volume of many molds is described on the basis of ounces of fat, not by total volume, because that is how experienced soap makers think. So for example, a 42 ounce mold will hold a batch of soap made using 42 oz (weight) of fat. Not sure if this applies to your situation, but it could.

 

[earlene]

I would guess it's a 3-lb mold, meaning to make 3 pounds of soap.

The reason I think this is because if you fill a 3-lb mold only about 70% full, you would have approximately 40 ounces of batter (or oil, or whatever liquid you put into it.) You can test this by weighing 40 ounces of water and pouring it into your mold and seeing if you get the same level as with your previous batch.

Now, if that turns out to be the case, a simple recalculation of your recipe to be 40 ounces of oil, should give you the total batch size that will fit in the mold at a more desirable height. (Total Batch size will depend on lye concentration, and any additional additives.)