Cutting Soap is Hard. :\
I made my task a little harder by making my soap harder. I like my soap to be nice and firm. Its makes it more durable, longer-lasting, a better value. The problem with that is cutting the soap into usable pieces afterwards. So even though I had really good soap, I had a lot of trouble figuring out how to split it into servings, and making them at least semi-consistent (spoilers: They still aren't 100% consistent, we'll come back to that.).
Method #1: The Wire Cutter
There are soap-making communities out there, and the general concensus (AMOGUS) is to get a wire cutter. We're talking about a steel wire, stretched tight across a wooden arm on a pivot. Nice clean consistent cuts, they say, no drag marks from a blade, they say. When my friend took the initial photos for my soaps, this is what I used. If you notice some white marks in the photos, those are, in fact, drag marks from the wire. It'd penetrate partway into the soap, and then stop. I had to apply slow constant pressure, and when it got to the bottom, it'd usually stick until I tightened the wire a bit more, causing it to snap through. Nice straight cuts, to be sure, but a slow process.
When I went back to those same logs a few weeks later, to do the actual packaging? Time had caused the logs to harden up a bit more. I broke three wires cutting two bars of soap. And those wires are a pain to replace. I came to the realization that this method was NOT going to work, at least not for me.
Welcome to your new home, wire cutter. You've been a real pantload.
Method #2: The Mitre Box
So I looked into some other possible solutions, and decided to try a mitre box. Its a box used for cutting angles in wood using a matching mitre saw. I wasn't looking to use a saw though: That'd be massive, thick, heavy, and far too rough, as a great man once said. No, I knew I needed a thinner blade with a smooth cutting edge. I looked into what was out there, and hit on the filet knife as the ideal candidate. Naturally, I went with the most meme-tastic blade I could get: I got myself a German steel filet knife from COLD STEEL!
...I assume there a town in Taiwan called "German." Anyhows, moving on.
I also got a wooden mitre box from Amazon. It has an adjustable piece inside so I could cut to whatever thickness I needed, and a nice thin slot that the knife goes down into, nice and straight, like so:
This method did not work nearly as well as I had hoped. There were two problems. One: The wood at the bottom is cheap and thin garbage. See that wing nut? Well tightening it made the screw tear straight through the bottom of the slot its in. It can never be adjusted again. Two, no matter how I held the box, the soap, and the knife, I could never QUITE get a straight cut. I did cut up all of my first batch saleable batch of Espionage this way (note the bits of grey in the bottom of the box), so the first ten or so bars I made are cut a little wonky. There should, however, have been 14-15 bars. The rest was waste, caused by the bars being the wrong size, cut at too much of an angle and needing to be whittled down or cast aside into the "soapfailure" pile. This was most definitely not going to work long-term. Still, the knife is okay, I still use it now and again.
Say hello to your little friend.
Method #3: The Guillotine!
This was not a problem I was expecting to have, like at all. I realized I might have to sink even more money into the process of cutting soap than I had anticipated. I needed something on a fixed arm, like the wire cutter, but it had to be far more robust, with an actual blade instead of a wire. Something like a paper cutter, but with a very thin blade, or a guillotine. Well I couldn't find a thing. What I was looking for was simply unheard-of. There were industrial solutions. By "industrial," I mean $8,000, USD. Maybe someday, but not at this stage! Amazon had failed me, the community had failed me, Google had failed me. In desperation I eventually fired up Etsy: Etsy had the solution, or at least one guy there did. It was an expensive tool, like $200, but I had to try it. Meet "Uncle Andy's Soap Cutter."
This was the answer I had been looking for. Adjustable. Sharp fixed blade. The soap stays in place, I get nice clean shiny cuts. If you make soap the way I make soap, this is the tool you need, totally worth it.
A Few Other Tools
So while I now have nice clean cuts going across the log, the logs themselves are of varying thickness and density, for reasons I am not going into in this particular article. I do adjust the thickness as I go. I aim for 4.5 oz per bar, with a .5 oz leeway. So, some bars may be 4 oz, some may be as much as 5 oz, if I'm not adjusting carefully enough. This gets me about 15 bars per log, with some underweight "waste" at the end (which still gets used elsewhere, so its not really wasted). But I do need to do some additional trimming to make the bars a more consistent shape. I do this with two tools:
Here's the mandolin, with a artistically placed curl of Programmer Socks that it cut. This is for planing bars where the cut was still not quite straight. The guillotine's blade does bend a bit sometimes, if I'm not careful. A mandolin is usually used to cut very thin slices of food: vegetables, maybe your fancy salamis, things like that. Very sharp fixed adjustable blade. Easy to cut yourself pretty badly on, but so long as you take the right precautions, its a great tool to have in your kitchen. Or your soap lab.
But while the mandolin is very very sharp, I have not cut myself with it. No, the thing that took off a chunk of my finger and a third of a fingernail while working on soap is the tool you'd least suspect: A vegetable peeler. I didn't photograph it, you know what a vegetable peeler looks like, right? Well, the one I have is really sharp, and I use it to clean up the edges of the bars sometimes. I held a bar a little too close to the edge I was cutting, used a lot of force, and wham, I had a bloody mess on my hands, literally. Needless to say, I did NOT sell that particular bar. The nail has mostly grown back as I type this, the finger is healed - hopefully it is the only accident I have during this whole enterprise.