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One of the best things about making biodiesel is the byproduct it produces: Glycerin. When we were making biodiesel, each batch produced 17.5 gallons of glycerin. We had so much of it, we didn't know what to do with it. So I turned to the Internet.
There are some pretty clever people on the Internet and they come up with some very clever ways to use biodiesel glycerin. One of the most interesting things I found was a stove made to burn glycerin. As it turns out, glycerin burns super hot! So, if you're looking to make a lot of heat and you have some biodiesel glycerin on hand, you've got the potential for making a LOT OF HEAT! But there is a drawback to burning glycerin. When you put the glycerin in the fire, if the fire is not hot enough to consume the glycerin, toxic acrolein fumes are produced. So yes, it can be used to produce heat but as with anything, you have to consider the bad -- not just the good.
There are other things you can do with glycerin. In some other countries, they accept all the glycerin biodieselers can produce and they put it in their sewage digesters. It promotes microbial growth and the beasties that live in the sewage love it! You can compost glycerin if you are so inclined. I've heard of people using it as a concrete form release so the poured concrete doesn't stick to the forms. But there was one other thing for which people used glycerin that really intrigued me; something that everyone needs and uses every single day of their lives: Soap.
I decided I was going to experiment with making glycerin soap. I had so much of the stuff, I thought, "If I can make soap out of all this glycerin, I could supply everyone I know with high quality soap for free! How cool would that be?" Again, I turned to the internet to find out how to make soap out of biodiesel glycerin.
There are many articles and YouTube videos out there describing how easy it is to make soap. Some people are very successful and they make it look so easy. I tried and tried and I made some stuff that would in fact clean my skin but it was ugly, really ugly! And it wasn't what I was trying to make. I wanted something of which I could be proud. The stuff I was making did not make me proud at all!
My best friend, Gordon, and I went to work trying to figure out exactly what we were doing wrong so we could make good soap. Obviously, following instructions we found on the Internet was not working so what could we do to correct our situation? Well, we ran onto a very nice guy on the Internet named Rick Knicely. He runs a web site called Knice n Clean which is a wealth of good, high-quality information. But more than that, Rick is a very nice guy; someone who is willing to talk to you and pass along great advice based on his years of making soap from his own (and other people's) biodiesel glycerin.
One of the things Rick told us was about "SAP Value", a short term for a very fancy worded phrase, "Saponification Value", also known as "Koettstorfer number". Without making it more complicated than necessary, the basic idea is: when you make biodiesel, you use an alkali (or Base which is at the opposite end of the pH scale from Acid) to chemically break the oil. Likewise, when you make soap, you use an alkali. But when making soap, you need to be very precise in your measurements of the ingredients including the quantities of alkali that you use. Now consider biodiesel glycerin. Invariably it contains non-reacted alkali... but how much? Who knows? Yeah! That's the problem! We didn't know how much alkali our biodiesel glycerin retained after reacting in the biodiesel process. So we had no idea how much alkali to add when making our soap.
Keeping Rick's advice in mind, Gordon and I set out to discover the SAP value of our biodiesel glycerin by performing a set of experiments. We made several small test batches of soap, each with incrementally less and less alkali added. At first, it was not very promising and we thought we were not going to find out the SAP value of our biodiesel glycerin. But we just kept on, each batch was a bit different than the last and sure enough, we started getting better and better quality soap. So we kept on. And after a while, our soap got worse - we had gone too far! We went back to the point at which we got our best results and we did a few small tests batches at that amount of alkali and lo and behold, we got consistly high-quality soap! Voila! That was our SAP value!
To give you an idea, when we started making biodiesel glycerin soap, we were adding alkali at an assumed SAP value of 25. After our experiments, we determined the best SAP value for our biodiesel glycerin was actually 15! What a difference! No wonder our soap was horrible before! We were WAY off! But no more! Now we were onto the right SAP value and producing great soap!
I said before, "When we were making biodiesel..." which would imply we are no longer making biodiesel. This is true. We had an accident and nearly lost our barn. Right after that, we decided it was not safe enough to continue making biodiesel. The risk was just too great. So, after 9.5 years, we stopped making biodiesel. I still had a lot of soybean/vegetable oil in storage and I needed a new project where I could use all that oil. SOAP! Yes, soap!
You see, soap, real soap, not the stuff you buy in stores these days, is made of 3 things: fat, alkali and water. All the other stuff in soap like scent and color and plant leaves and anything else is unneccesary to make soap. When you combine fat, alkali and water in the correct ratios, you get a chemical reaction called "saponification" (remember that word?) which is the process that takes place resulting in soap: pure soap. And don't be fooled about anything uneducated people say on the Internet. When you put these 3 things together, a chemical reaction takes place which changes them and makes them something new that they weren't before. The fat is no longer fat. The alkali is no longer alkali. And the water is only present to put the alkali into solution for mixing purposes - it evaporates off in time. That's soap, folks, pure and simple. And it is NOT detergent.
Gordon (my best friend) and I started out small and as we gained confidence in our ability to repeat the process of making high-quality soap batches, we started increasing the size of our batches and making more and more soap each time. If you think about it, the time it takes to make 32 oz of soap is pretty much the same amount of time it takes to make 40 lbs of soap! So if you're going to make soap, we thought, why not make a LOT!?!
Larger batches of soap are heavy and they can blow out the walls of your homemade soap molds. If you use cardboard boxes for molds or something flimsy like that, you're likely to lose your whole batch of soap and have a big mess on your hands. Gordon and I tried FedEx boxes, empty plastic milk jugs, and 3-inch ABS (black) pipe. They all worked but they were all a hack just to get by. Finally, I broke down and went to Etsy.com and found a guy who agreed to make me some HDPE soap molds to my specifications.
I did the math. I knew I wanted my molds to be 20 lbs each and my bars to be 1.5 inches thick (I like large, man-size soap bars). I had a general idea of how large I wanted the bars to be and after doing some easy calculations, I ordered soap molds that were 50 inches long and would yield forty 1.5-inch wide bars from a 20 lb batch. Perfect! And after making numerous batches of soap with these molds (I bought 2 of them), the bars of soap come out to about 8.2 oz each. Now that's a healthy bar of soap! One thing I would like to mention about trough or loaf molds: If you go to someone and ask them to make a mold for you using dimensions you specify, remember to order your molds a little bit deeper than the actual height of your actual soap bar. If you don't, you are likely to have a mold that is overflowing and that is a frustrating situation. I didn't do that! I gave my mold maker the actual dimensions of my soap bars and didn't realize 20 lbs of soap would fill that mold to the brim or even to overflowing!
At first, I cut the bars by hand with a butcher knife. I used a tape measure to mark the loaves of soap at 1.5 inch increments. Then I did my best to cross-cut the soap loaves at the marks but try as I might, I wasn't very accurate and I got soap bars that were weird looking and misshapened which frustrated me.
Back to Etsy.com I went. This time I was looking for someone who could make me a soap loaf cutter but give me the width I wanted rather than something they had on hand. I found Bud Haffner, an Etsy craftsman, who agreed to make me a soap cutter wide enough to cut 1.5 inch wide bars, 12 at a time. Perfect! Here's a picture:
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