Cutting curing soap

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Rpod

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From beginner resources I've read/watched, a big deal is made of keeping your soaping tools and utensils separate from kitchen equipment. i.e. don't use tools you've used for soaping for food because of lye contact. That's mostly fine with me but I'm wondering about if this includes, or how big a deal it is, using a kitchen chef's knife to cut curing soap. I have a sheet of soap that's been curing for about 2 weeks. I used a plastic container to mold it, so it's about an inch high and maybe 8x8 inches square. Anyway I want to cut it. At this point, should it be safe to use a knife I plan to use for food to cut it? Or should I really dedicate a soaping knife?
 

lsg

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IMO, it is safe to use the knife as the soap has already gone through the saponification process. I wouldn't use the plastic container for food products, though.
 

Rpod

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Ok thanks for the reply. Since I'm not totally sure, how are saponification and curing different? I understand that full curing can take many weeks, but is it reasonable to assume saponification is done in a couple days?
 

The Efficacious Gentleman

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You can zap test (check out the stickies on that) to see if saponification is finished. Curing varies depending on the person and the recipe, but 4 weeks is usually the least people will cure for.

As for utensils, bear in mind that people use lye in cooking, albeit weaker than we tend to mix it at. My biggest issue is with the scents - fo taste on things for a while might not be so welcome in the household, depending on the FO, of course!
 

Gerry

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Ok thanks for the reply. Since I'm not totally sure, how are saponification and curing different? I understand that full curing can take many weeks, but is it reasonable to assume saponification is done in a couple days?
Yeah that's safe to assume. Doing the "zap" test will confirm it. If your soap warms up enough during saponification to gel, it could be complete in well under 24 hours. My ungelled, pure olive oil castile soaps take about 55 hours to fully saponify at room temperature.

Curing is what happens to your soap after saponification is complete. During the process they lose water to evaporation and get harder, and other unknown things happen with time that generally improve your soap. It's much like wine. Once fermentation is complete after a few days, wine is not ready to drink and must be aged for at least some time first. While the reactions in aging wine has been studied by science for decades now, there is very little known or studied about what goes on inside our soap.

One of the main reasons we do not mix our soap making equipment with our food implements is that silicone, plastic, and wood in particular pick up the fragrances (EOs & FOs) that would transfer to the food in contact with it, even after being thoroughly washed or put through the dishwasher. Lye isn't the problem. Stainless steel doesn't absorb scents the way other materials do, so it's fine. Don't of course use anything aluminum or containing aluminum in soap making.
 

LilyJo

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Yep have made that mistake in the past - amazing how you know what the fragrance is from the taste rather than any smell.

Do it a few times and you soon learn to seperate your utensils!!!
 

Susie

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http://chemistry.about.com/od/chemistryglossary/ss/Saponification-Definition.htm

"Saponification
Definition: Usually, a process by which triglycerides are reacted with sodium or potassium hydroxide to produce glycerol and a fatty acid salt, called 'soap'. When sodium hydroxide is used, a hard soap is produced. Using potassium hydroxide results in a soft soap.

Lipids that contain fatty acid ester linkages can undergo hydrolysis. This reaction is catalyzed by a strong acid or base. Saponification is the alkaline hydrolysis of the fatty acid esters."


Saponification takes anywhere from 24 hours to 1 week to finish. If you gel, the time is shorter. If you don't, or if you put your soap in the freezer to prevent gel, it will take much longer. You can tell if saponification is complete or not by the zap test.

Cure takes 4 weeks up to 1 year. It is the process of the crystalline structure of the soap being formed, moisture being lost, and some indefinable but important changes of quality.

Some people on YouTube would have you believe that hot process soap is "cured" at a few days. It might be fully saponified, and therefore safe, but it is not cured.
 

mx6inpenn

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I separate most of my utensils, however I have a deep stainless steel bowl that I have used for soap on a couple of occasions when I needed a larger container. I also use a knife (again, it's stainless) for soap and regular kitchen use. I won't mix any plastic or silicone between the 2, but well cleaned stainless steel won't has residual fragrance or oils. It's non-porous and used in commercial kitchens to avoid cross-contamination for just that reason.
 

IrishLass

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My stainless steel utensils/pots pull double duty for food and soap, but I keep separate sets of plastic and silicone utensils. Not because of the lye, but because of the fragrance oils I use in my soap. Their scents permeate/carry over into plastic and silicone, but not so with my stainless steel.

For what its worth, I make my soft pretzels (laugenbretzel) the "old world" way, with lye. Basically, I give the raw pretzel-shaped dough a brief 30-second dip into a bowl containing a room temp 3.84% lye solution before baking them. The brief 30-second dip into the lye solution is what gives them that authentic, pretzel-y taste. For those that might be having any skittish thoughts right now, the lye solution converts to harmless calcium carbonate during baking.

Chemistry- its a beautiful thing.


IrishLass :)
 

Susie

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I have sometimes wondered if a weak lye solution would be good for getting that oily feel off of plastics used for soaping
I tried it at 1 oz NaOH/gallon, with no improvement noted. I think that oily feel is oil soaked into the pores of the plastic. I get the best result from Dawn dish detergent, and wash twice.
 

Catastrophe

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I swear my husband can taste "soap" (he means FOs) on stuff that has never been within 10 feet of it. He watches me use kitchen knives on it, though, and has never complained about tasting it on them. I agree that the "flavor" only gets carried over on non-stainless items.
 
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