April 18, 2012

Making soap

I've been wanting to get into soap making for a little while now. I tried two tiny batches last friday night.

We don't use all that much soap at our house, but it would be cool if the hand soaps in the dishes by the sink in the two bathrooms were home made. Becky and I share a 1L bottle of Dr. B's for showering; it would be neat to make that too, or a reasonable approximation of it. I've recently embarked on a journey to switch from shaving with an electric to a straight razor, and I would also like to eventually get to exclusive use of my home made soap.
For the handsoap, I decided to go with something easy for my first time. I picked a castile soap recipe from millersoap.com, and scaled it down. I was thinking of adding in rosin at some point in the future, and I didn't find a lye calculator online which had rosin in its database. So I worked up a spreadsheet which is barebones but gets the job done. I posted it on my Google docs if you are interested; it has the original recipe from Kathy Miller, a scaled down version for a one plus bar size batch, and a version with 10% rosin.

The list of ingredients I used for this first soap were:

128g olive oil (from the kitchen)
36g coconut oil
36g palm oil

27.74g NaOH
54.49g H2O

Pretty basic in other words. I brought the dissolved hydroxide into the melted oils when both were at 43C. Then I started stick blending it. It seemed to take a long time to trace, though I obviously don't know exactly what I'm looking for to ascertain that condition. But after 8 minutes of mostly on sometimes off stick blending at a level of 2 out of 5, it felt like it was significantly thickened, so I poured it into a piece of 2" PVC for a mold.

Having everything out and dirty, and feeling like the first one had gone fairly well, I decided to give the shave soap a go.

I found a thread at B&B started by charles_r on home made shave soap. Much or even most shave soap apparently uses a high percentage of KOH for saponification because it makes better use of the stearic acid in the base oils, which makes for more stable lather. KOH makes softer soap too, which I suspect is good for getting a good wad of it onto your brush without working too hard. This recipe by charles_r uses both KOH and NaOH, which I didn't find a lye calculator capable of doing, so again I worked up a little spreadsheet myself.

Here are the measurements I used for my micro batch (I used palm oil instead of beef tallow):

66g palm
66g stearic
40g coconut
28g castor

10g NaOH
26.2g KOH
72.7g H2O

1 tsp kaolin
1 tsp peppermint oil

Everything went ok until I put the hydroxides into the oil. Hydroxide was 41C, oil was 48C. The second I turned on the stick blender it turned into mashed potatoes! I tried mixing it up with a spatula and packing into a PVC pipe. In response to a posting at B&B, charles_r recommended moving to hot process where you don't have to worry about temperatures and trace as much. He says straight stearic acid traces instantly, which explains my experience.

The second I turned the blender on the mixture instantly seized up. After that I couldn't really do much with the stick blender; the batch was so small that the blender couldn't really get purchase on enough material to do anything once it was solid enough to be mounded up around the edges of the tiny pot I was using. So I just mixed it around with the spatula and loaded it into the mold.

I became concerned that neither soap was very warm when I finished molding it and wrapping in some towels. After doing some reading, I began to think perhaps the batches were too small to hold in the heat of the reaction enough to get as far as it was supposed to in the first 24 hrs. So I took both molds and put them in my oven at 80C for four hours, then left them in the turned off oven overnight. I read about some people doing this online to help with insuring a gel stage and more rapid cure for cold process soap.

The next day I pushed them out of the molds and cut them up. The shave soap looked ok, though it was a lot softer than the castile bar. The castile looked a bit un-homogenous, which could be cause for concern. Now I've got the little soaps on a cardboard box in the closet. I'll let them cure for a few weeks and see how they are (after pH testing with pH paper).

I had the trident printing block out from when I stamped a design into my strop the other week, so I tried pushing it into the soaps. The softer shave soap took the impression well, but the castile was too hard already to make much of an imprint.
On the whole the process seemed about as difficult as making chocolate pudding (from scratch of course!). So no reason not to do it a few times a year to keep yourself stocked with soap, right? Of course none of the ingredients for chocolate pudding can make you blind...
I can hardly wait to try these out. Hopefully they won't melt my skin!


Anonymous said...

How did your shaving soap turn out?

Holly Gates said...

It turned out great. I really like the stuff, and I have a couple years worth at the rate I'm using it. I did another batch, but hot processed and with rosin as a small percentage of the oils. I also added the superfat (in the form of avocado oil, with vitamin e) after most of the saponification was done. The HP soap looks like ass, but it was quick to make and I like the updated formulation better. You can find the ingredients I used for the HP batch at the bottom of this file:

Unknown said...

Hi! I'd justl ike to share with you a lye calculator that allows use of both NaOH and KOH simultaniously.


Reading through you're blog tonight, I see you're familiar with Catherine Failor and her methods for soap making. This calculator was designed based on her books. Hope it's helpful to you in the furture. It's been the go to for us liquid soap makers, as it accounts for the impurities in KOH.