Silicone mold size cavity effecting hardening process

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Garden Gives Me Joy

Well-Known Member
Jan 25, 2020
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United States
I believe I am seeing a patter across 3 slightly different brine soap batches so far with these molds. I pour a single batter into both (that smaller for samples). However, I notice that the small sample bars take considerably longer than the large ones to harden enough before I can unmold. Is this normal? In one case the big bars were ready to be unmolded within about 9 to 12 hours. However, I needed to wait for over 24 hours to unmold the sample bars.

Can I do anything to speed up the hardening of the small sample bars? Would insulating them somehow help? On a slightly different note, when I increased my batch sizes, I noticed that the lye water temperatures rose higher than it did with less mass. So I wonder whether something similar is happening.

FYI, the large cavities hold roughly 130 g while the small holds roughly 20 g.

Molds - cavity capacity relates to hardening process of CP soap.jpeg
I made some miniature donuts...took a week for them to harden. I have notice with making smaller size soaps...2oz or less...that they need more time in the mold. I would like to say that it's because the smaller amount of soap doesn't generate heat, but I make GMS and refrigerate it with no real problems.

When I was making wedding soaps (lots of detail), I found it helpful to double my Sodium Lactate and increase my Lye Concentration. You could try that. You could place the molds on a heating pad on low for an hour. You could put the molds on a cookie sheet and CPOP*** them.

***CPOP - Heat your over to 170F, turn off, put in soap and leave overnight.
I agree with @TheGecko and would add that I use a heating pad under my cavity molds, and I put an insulated cooler over the top of all that. I only leave the heating pad on for an hour, which builds up enough heat inside the inverted cooler that the soaps usually gel and harden within 12 hours.
Ok so this popped up on "similar threads" so I guess that gives me permission to necropost LOL. I think it is worth bringing back the topic anyway.

So I have noticed this same problem as the OP. I can make a whole loaf, or even a whole slab mold of soap, and it will be ready to unmold way quicker than little over-pour bars in individual silicone molds.

This is something that has perplexed me for over two years. Today for instance: I made a batch of OMH soap yesterday. I poured my leftover batch into two individual bee molds. I pulled the whole loaf out of its silicone mold...let it harden a little, then cut. AFTER all of that time, I popped a soap out of the little bee mold and it was all squishy.

I presume it is about the way it heats up and/or gels. In the end they both look the same so I really don't think it was a gelling issue.
@Catscankim I want my soaps to gel, and to ensure they do I put everything on/under heating pads and wrap in a blanket. The little cavity molds as well as the loafs and slabs. If I don't do this, the cavity molds take days and days to get hard like the loafs do. Even if you aren't trying to gel your loafs, they may well do that anyway given your warm climate and the addition of milk and honey to your batch. If you aren't adding colorant, you might not see a big difference between gelled and ungelled soaps.
Most of my smaller cavity molds do take longer to firm up if I don't put them on a heating pad. I think it's because there isn't enough mass to generate enough heat to go into gel.

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