Discussion in 'Lye-Based Soap Forum' started by John Harris, Nov 6, 2019.
Would a pressure cooker work for rebatching?
Oh no no no no no...don’t do it!
No, but I have seen people use a pot on a stove to melt the soap or use a bowl over a pot of simmering water. I use a cheap crock pot I purchased specifically for making soap.
A pressure cooker elevates the temperature of boiling water. Why do you think this temperature elevation would be helpful? How would you propose to rebatch in a pressure cooker?
Not saying it's a bad idea, but I'm not saying it's good either. I get the impression you're throwing a random idea out in the breeze to see where it lands. I'm not sure I'm up to debating with the wind. Give some background, please, to help me (and others) understand what reasons you have for asking.
I have never put anything like soap under pressure. You can use a slow cooker or the oven to rebatch. I usually grate the soap and add a little water, then rebatch in the slow cooker. I have found that adding a little instant powdered milk at the end of the cook helps smooth out the soap for a smoother pour.
I don't think John is asking you to debate, he's just asking a question. Here is the original thread where I brought up rebatching soap.
Yes, I get that he asked a question. I'd just like to know the reasoning behind why he's asking -- I think that's a fair expectation to have, especially for a question about an out-of-left-field topic like this.
I too would be interested to know why you think the pressure cooker would be a good idea. I wouldn't risk it to be honest unless you're doing it on another setting and not under pressure.
You wouldn't have any way to see what it's doing if under pressure.
Or you could just run it as an experiment with some less than beautiful soap and record what happens at various time intervals. Who knows? Maybe it would turn out to be the best way to rebatch ever!
I'm just looking for a way to really melt the soap shards well - to liquify the soap in the cooker. I wondered if the power of a pressure cooker could do it more thoroughly. One of my life sayings is "If you want to find the easiest way to do something, give the job to a lazy man." I was just looking for an easier way, that's all.
I once experimented with cooking the noodle in the pressure cooker because I was hungry and didn't want to wait the 20 to 30 minutes for them to cook. I was VERY lucky I wasn't in the kitchen when the lid exploded, embedded itself in the ceiling and I had to spend two hours cleaning and had no supper. The pressure turned the noodles into a gelatinous mess and the plugged up the hole where steam it offset by the little thingy.
I have no doubt that @John Harris is looking for a quicker way to rebatch, but sometimes time is our friend, not our enemy.
When I was in Junior High, one of our jobs was to water the trees that we had planted...pretty easy for the first batch of trees as the hose reached, but the ones by the road required hauling buckets of water halfway across the yard (we had a big yard). I came up with the brilliant idea of carrying two buckets of water...except by the time I got to the trees, instead of two full buckets, I had less than two half buckets AND it took me longer to walk with two buckets. Moral to the story, the 'easiest' way isn't always the best way.
I have no interest in rebatching soap myself, but I done the research and if I were to do it, I would first start by preheating my crock pot/slow cooker and adding my initial liquid and letting it get hot or using preheated liquid. I would then grate my soap finer using my vintage Salad Master (you can find them on eBay) and then adding the grated soap in small amounts to the liquid.
Thanks for clarifying, John. Much appreciated. IMO, the goal when melting soap is less about using high temps and more about getting the soap up to its gel temperature and holding it there and encouraging a modest amount of moisture to efficiently penetrate through the solid soap bits.
The disadvantage of a pressure cooker/canner is the temps are well above the boiling point of water, so the soap is at more risk of overheating. It could even scorch, if the water content in the soap drops too low -- there is minimal control over evaporation in a pressure cooker. You also can't quickly and easily check the soap in the cooker to see if it's fully melted. I don't want to overheat the soap and I want to get it off the heat as soon as possible.
Things I've found to help soap melt efficiently --
First step is to get the solid soap broken down into pieces as small as is reasonable. I grate it in my food processor with the cutting blade if the soap is hard. I will use the grating blade if the soap is soft.
Melt the grated soap when it's relatively moist but not soaking wet. Ideally, you'd melt the soap when it's freshly made and naturally already has a high moisture content. If the soap is older and very dry, I add water to dampen the grated soap thoroughly, then let it sit for a time in a closed container at room temp to absorb the liquid.
Melt the grated, dampened soap in a covered pan in the oven at a low temp -- 160-180F / 65-80C. This is a little above the temperature at which soap typically goes into gel. Benefits -- No hovering or continual fussing required, no fear of burning, easy access to the soap for the occasional check and stir.
A crock pot also works if that's your preference, but there's more chance of soap on the edges of the crock pot drying out, due to the way crock pots work.
I rebatch just like DeeAnna spelled out above. Works great! I use one of my stainless soup pots of appropriate size w/oven-safe cover and 'cook' it at 180 degreesF. It doesn't take much more than 30 minutes to 1 hour tops. The oven is great because it provides nice, even all-around heat without the pesky problem of hot spots.
You could not pay me enough to use a pressure cooker to rebatch. I love my pressure cooker cooker too much.....and my ceiling! lol To use pressure cookers safely and properly, you need a certain minimum amount of liquid in there, and the amount I use for a rebatch is not anywhere close to what I would need to be able to pressure cook it safely......and/or without it scorching.
I recently had to rebatch and I didn't have a crock pot to put it in so I just put it on the stove on medium, chopped up my soap into small cubes, added the oils I had forgotten, and then when it was all melted I used my hand mixer to thoroughly break up and mix it all up to ensure it was completely melted and mixed. Then I just put it on low and watched it while stirring. I think it took about 20 minutes for it to be completely melted and mixed and then maybe another 5 to get to the vaseline stage.
I would not use a pressure cooker because 1 you won't have any water evaporation so it's not going to get glossy and finish, 2.you need to stir it so that it mixes correctly and you can't do that with a lid on, and 3. if your vents get clogged by expanding soap you risk your pressure cooker blowing up.
I find melting in the oven at 180-200ºf gives a much better smoother melt over stovetop or crock pots. You will still need to add in some liquid but will end up will a very molten soap.
It is not possible to work with a Pressure Cooker without water. An aqueous HP will be wet by the end of time.
I've often eyed my InstaPot thinking what if ...
I wonder if a rebatch would work with the pot-in-pot method where you have a cup of water at the bottom of the pressure cooker, and then another covered pot containing the soap pieces inside the cooker. I have not been brave enough to try.
You took the word out of my mouth! Yes. This is another option. You should try a cheap pot.
Ah.... Nice to meet people as crazy as I am!
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