Wednesday, December 17, 2008

a bit out of practice, apparently.

the other thing i did this weekend while kerry was here was make a batch of soap. i also made another last night, and if not for the fact that i ran out of olive and coconut oils, i would make a third tomorrow night. my mother requested soap for christmas because she bought some that gave her a horrible rash and mine do not. nice.

kerry also got a brief lesson on soapmaking. here it is: soap is made through a chemical reaction called saponification, in which weak fatty acids are turned to soap in the presence of a strong base. oil (olive, coconut, canola, corn, shea butter, whatever) is made of weak fatty acids. lye (NaOH) is that strong base. just like fight club. which, by the way, has that fabulous line: "we were selling rich women their own fat a$$es back to them." what a great movie.

soap is uber-easy to make. i use the cold-process method: melt all your oils together, mix the NaOH with water, let it all cool to about the same temperature (about 115º), and mix the two together. stir stir stir (i use a stick blender) until it becomes about the consistency of cream soup. this point is called trace, and when soap traces then it is time to add all the special things. herbs, essential oils, colorants, etc. then you pour it into a mold - you can use anything. i use a wooden slab mold with a silicone liner from upland which i absolutely love (it prescores the bars for easy cutting) but in the past i have used pringles cans, tupperwares, shoeboxes, muffin tins, you name it.

when soap goes in the mold it is only about 60-70% saponified, which means there is some unreacted oil and unreacted NaOH floating around. the mold needs to be insulated, because the saponification process is an exothermic reaction (meaning it gives off heat - remember high school chemistry?) and that heat needs to be conserved to continue the reaction so the soap is fully saponified. so you wrap the mold with towels and put it in a warm (or not cold) place. my wooden mold is actually a great insulator so i don't have to insulate; i just pop the mold in the oven (off) after i've warmed it a little. let it sit for about 2 days and then pop it out of the mold, cut into bars, and let it cure for 4-6 weeks to allow the water weight to dry from the bars. curing is not 100% necessary but it helps give the bar a nicer feel and it doesn't dissolve as fast in the shower.

the tricky part comes when working with the additives, usually. herbs and things like oatmeal are not too much of a problem because they don't react with anything. they just kind of hang out and look pretty and act all nice and exfoliating in the shower. nor are colorants much of a problem; you either mix them in thoroughly for even color or not so much for a swirly look. the thing to watch out most for is the things that will react: milk, honey, and especially essential and fragrance oils. milk and honey will increase the temperature of the reaction; milk also discolors tan to brown, depending on the quantity and when it's added.

most eo's and fo's are relatively stable, but some are not so much. some you have to be very careful with because they have a low flash point. (not so much of a problem in cold-process soap, since the temperatures are lower; in other methods it can be.) others - namely the musk i used in conjunction with other scents last night - can have a tendency to accelerate trace, which means your soap gets very gloppy very quickly and is hard to work with.

and here is the crux of this very long, very involved post: i completely forgot last night to check if any of my scents acted funny. usually i know how they will behave, but this one i don't use very often and completely forgot about. my soap got so gloppy so quickly that i could barely get it out of the pot and into the mold. and then i checked bramble berry's website and read this: "this fragrance accelerates trace in a dramatic fashion. do not water discount with this fragrance and be prepared to work quickly with the fragrance."


i'll post photos soon, because the one i did on sunday turned out really pretty, and i really like it.


Anne-Marie said...

Oh no! How is the soap now? I hate it when I forget to check notes and end up trying something ambitious, like a triple swirl, and then viola! the soap hardens up like a rock before I even get one color swirled in.

eireann said...

it got all nice and hard very quickly, and smells great. i guess i learned my lesson the hard way - now i will always check notes before soaping!