Lyes, all lyes!

May 12, 2009 at 10:01 pm | Posted in Blackpowder, saltpeter | Leave a comment

After three times dripping through the general mixture, I thought my saltpetery water was ready to go to the next step, which involves boiling the mixture to reduce it. However, I’d completely forgotten that the boiling step requires lye. So the saltpeter water gets to drip through a fourth time while I make a batch of lye.

Biringuccio directs us to “make a strong lye of three-quarters of soda or ashes of cerris or oak…and one quarter of lime.” He does not, however, give specific instructions on how one would go about making lye. I knew in general terms that you dripped water through ashes (dripping water through other materials appears to be a theme of this project), but I wanted to be specifically medieval. Since I’d forgotten that I needed lye, I didn’t have any reference book on hand, but luckily the internet was ready and willing to provide some documentation.

I looked at several medieval recipes for lye, most of which were given in the context of soap-making. I finally decided that while I would use Biringuccio’s recommended 3 parts ash to 1 part lime (seen in the photo at left), I would also use the methods given in Mappae Clavicula: A little Key to the World of Medieval Techniques, a translation of a 12th century document. I saw this recipe in several places online, most notably here. I used the one labeled “Making French Soap.”

Basically the recipe indicates that one should make a paste out of lime and ashes, then press it on the bottom of a basket (which presumably acts as a filter.) You need to “make on top a place for the water so that it does not run away”. Then you drip the water through the mixture and collect it in a container underneath the basket.

I had plenty of baskets, so I chose one that had a fairly tight weave and looked like it would be about the right size to sit on top of the container I had in mind. It ended up being a few centimeters too large, but otherwise was perfect. I was a little worried that the basketweave was not going to be tight enough to act as an effective filter, so I “cheated” and added a piece of cheesecloth to the bottom of the basket.

Next, I mixed together the lime and oak ashes that I still had left over from when I put together my saltpeter mixture. The first batch was not enough to properly fill the basket, and was a bit watery, so I used it as a bottom layer and made a second batch that was more of a thick paste, which I used like playdough to make the sides that would keep the water from “running away.” I then poured water into the little bowl I’d created and voila! Instant lye machinery. I plan to run the water through a few times to increase the strength. Apparently I need to be able to float an egg in the solution before it will be considered a “strong” lye.