Wednesday, February 19, 2014

Yucca Sandals #2

This post is a followup to the comment submitted on my earlier post (Thank you) about dry vs fresh fibers. The question at hand was about drying the yucca leaves before weaving them, but led to some interesting experiments in general.

Defining my goal

I am primarily interested in what can be done in the extremely short term (half-day timeframe) to protect the feet given no tools other than two working hands and only naturally occurring materials. Producing the best sandal possible from yucca might start with producing yucca rope, then making some Wuxi-style rope sandals. That would require a lot more yucca, a couple of days drying, and some simple tools. Perhaps I will make a "luxury" sandal when all this is done.

Yucca Sandals #2

General pattern
for sole
I picked the leaves and set them out on a dry indoor surface for 48 hours. Then I proceeded as before. The immediate results were pretty much what I had expected: The leaves had shrunk a little, though not much. They were much more pliable, too. I had been worried that in their softer state, the "skin" on the leaf might not hold together as well and they would just shred or tear rather than fold. That was not the case. They folded quite nicely, even bending without breaking at first, which let me fine-tune the location of the folds before committing. An additional advantage in using aged leaves was that the pointy-bits that stuck out were softer, and less likely to jab you in the foot.

The leaves had shrunk a bit before the weaving, so proceeding with the same construction as in case #1 led to a narrower sole. Easy enough to fix, if I wanted to: add another V strand when I start.

Overall, the resulting sandal was better than the first.

The surprise came the following morning:

Sandal #2 after 24 hrs
Sandal #1 after 24 hrs

While the gaps that formed were not nearly as big as before, they were still significant.

I was pretty sure this came from additional moisture leaving the leaves when I halved them before weaving, and possibly also from the breakage at the fold points. My conclusion is that just leaving the leaves to dry for a day doesn't get enough of the moisture out to avoid gaps and looseness in the sole.

Things I learned

Pattern for
"contrary" edges
  • The leaves still shrunk (again mostly on the width dimention) even after the leaves had been dried
  • Having the folds at the edges of the sole go the "easy" way rather than the contrary way lets the lacing move around a lot.  If I made them contrary it might make the laces more stable.
  • I can now make a single sandal sole out of freshly picked yucca leaves in about 10 minutes. I assure you that this is not a skill I had ever expected to acquire. The Computer Science Curriculum at university did not offer a class in Paleolithic Clothing Manufacture, but even if it had, I doubt I would have taken it. Live and learn.

Next Steps

Some more experiments suggest themselves:
  1. A third pair of sandals made with leaves that were sectioned immediately after picking, then left to dry for 48 hours.
  2. Drying the yucca leaves over a fire and trying to do it all in one day again
  3. Making a double-wide or double-long sole and folding it over to get a thicker and more protective sole.

Thursday, February 6, 2014

Spinning yucca fibers: some notes.

This process is fairly well documented in several YouTube videos, but having done it myself a fair bit, I wanted to add or clarify a few details that the videos glossed over.

Spinning methods.

There are three main methods of spinning twine, and like the gears on a bicycle, they're a continuum of the tradeoff: easy vs fast. Here are some videos that are good examples of each
Hand over hand is the easiest to learn, and the simplest to get started. It requires only one working wrist to do the twisting, and is very reliable for someone just starting. The downside is that it requires at least two twists and one exchange per twist of the twine. That's a lot of motion for a small amount of twine.

Counterspinning is somewhat harder, and somewhat faster. It requires both hands to twist the twine in opposite directions, but there are no exchanges between the hands, so you're always making twine. Also, the twine itself hangs freely in the air between your hands, so it may not be as tight a spin as you would get with hand over hand.

Thigh rolling is definitely the hardest. It doesn't always involve your thigh - it needs a smooth, flat mildly frictional surface. A human thigh (sans hair) is an excellent choice and almost everyone has a couple within easy reach of their own hands. Thus the name.

Which one you use depends a lot on how much twine you make in your lifetime. If you just want an inch or two of twine to show your friends, hand-over-hand is your friend. If you're doing a single project and need a yard or so of twine or even doubled twine, counterspinning may be the way to go. If you think you might make twine on more than three days in your entire life, taking the time to learn how to thigh roll is definitely worth it.

Update (11-Feb-2014) The folks at Stone Age Skills report being able to thigh-roll 3 meters of 4mm rope out of yucca fiber in 15 minutes.

Working with yucca

Scraping off the green stuff

The top side of yucca leaves is a continuous, smooth sometimes shiny surface. It contains none of the fibers, but serves as a sort of gluey mat to which they bond. Scraping it off with a nearby stick or rock is not hard after your second or third try. You can do this step with your thumbnails if you need to, but that's more effort. The only real danger is pressing down fiercely and breaking some of the fibers.

Top: A scraped section of leaf next to a pile of the scrapings taken from it.
Center: A more heavily scraped section of leaf.
Bottom: The scraping has gone to the point of separating the fibers.

Above, you can see progressive examples of thumbnail-scraped yucca. I try for something like the bottom example. A few broken fibers is not a problem, but every broken one probably sits adjacent to two more that are almost broken, and when they are incorporated into the twine, they will break under stress, making the twine weaker. Thus the loss is slightly worse than it appears. Going much beyond the third example will give a lot of damaged fibers, and a potentially weaker twine.

Not all the videos cover scraping, and since yucca twine (of thicker fibers and lower quality) can be made skipping this step, that explains the absence. On the other hand, with a dull straight edge, it's very little work in exchange for much finer fibers, so I think it's worth it.

Drying before spinning

This is way more important if you skipped the scraping step. After a few days in the fresh air, disconnected from the yucca plant, the leaves will shrink (across the leaf) substantially - sometimes as much as 40%. If you spin undried, unscraped yucca fibers into twine, the twine will be mostly useless within 48 hours, due to the twists unravelling. The fibers themselves are getting narrower, and need more twists to stay together. But your twine was spun before the shrinking. Now the curls just stand empty, like this:

Spun fresh: left, dark green
Spun dry: right, light green
If you scrape and dry your leaves, you can get very fine fibers suitable for making thread instead of just twine. Or you can spin them in larger numbers to make much stronger twine.

About that "yucca soap"

For what it's worth, most people don't notice anything other than a somewhat gluey or tacky layer on their skin after using it. Some people find it irritating. I am at the "mildly itchy" end of the spectrum, but other people can have strong and/or painful skin reactions. Yuck!  Just keep it in mind the first time you craft with yucca so you can grab a quick antihistamine tablet if you need it. Even if you do have a strong reaction, wearing gloves when cutting off the root of the leaf and scraping the leaves may get you through. The fibers themselves have not caused problems for anyone I know. As always, YMMV, I am not a doctor, etc.

Wednesday, February 5, 2014

Yucca Sandals #1

Aside: The current plan is for this blog to be a catch-all for stuff that doesn't fit in Paleometallurgy or Bootstrap Chemistry.

Yucca Sandals #1 (no tools)

Or: How to turn nine leaves of yucca into a pair of survival sandals.

I wanted to get a feel for what it would take to make some footwear from absolute scratch - materials you could find in the natural world, using no tools of any kind besides your hands. Since I live in California, yucca was a reasonable choice. I expect birch bark or cedar would do just as well.

There were a couple of videos on YouTube (links below) that showed parts of what I needed to know, but not everything. Some experimentation was required.

Gathering materials

I started with some broad-leaf yucca plants. I pulled individual leaves from all over the plants I had available, so I did as little physical and aesthetic damage to the plants as possible.

Left: front of leaf. Right: back of leaf.

I removed the root and tip, then split the leaves and removed the spine. This gave me half-leaves approximately 35cm long and about 2.5cm wide.

Fresh, undried yucca

Yucca shrinks in strange dimensions as it dries from its fresh-picked state. Here are some examples of my first weaving experiments. When I made them I wove each one as tightly as I could. They looked like this two days later. Note the large gaps. On the order of 40% of the width of the original leaf has gone away.

Tests: left to right: 2-plait half-leaf, 4-plait quarter-leaf, 3-plait half-leaf.


Sizing an item like this involves two things: the distance covered by a leaf section, and the distance you want to go.

Since I'm doing a diagonal weave, the effective width of a strip is the diagonal of the strip width, rather than the width itself. Back to high school geometry, the diagonal of a unit square is the square root of two. (Approximately 1.42)

Multiplying the width of the leaf (2.5cm) by √2 gives 3.55cm (~1.4in) per strip. I have large-ish feet  (US men's 10½) so given these widths I need sandals three strips wide by seven or eight strips long. This will leave plenty of room to wrap the sole up around my foot, keeping the laces out of contact with the ground.

Weaving sandals

I started with the leaf bent once in the middle, the V-shape that the first video shows:

Then I made two with a U-bend, turning the two ends in opposite directions:

This gave me a width of three plaits:

I wove for five, then collapsed the sixth and seventh to put a toe on the end.

The sandal sole above is made from a total of nine leaf-halves and was finished in 30 minutes.

Running twine along both edges and across the back, I crossed everything behind my ankle and tied it in front. Here's the finished sandal, attached to my foot:

Things I learned

  • Once I got the weave started, the rest was much easier than I thought it would be. Given how many variations and decorations there are in the plethora of videos on YouTube about weaving various species of dried plant, I had expected it to be more complicated. It wasn't. Young kids could easily learn and do it in an afternoon.
  • Sandals made from fresh-picked yucca leaves will probably only last one day because they shrink, much like yucca twine made from green fibers.


  1. I would guess that with practice I'll be able to go from picking yucca leaves to two complete sandals in well under an hour.
  2. Sandals like these are for protecting your feet from rough ground and some cuts. Thorns and the occasional sharp pointy rock are still going to punch through.
  3. If I were doing this for real, I'd probably pick enough for three pairs the first day (something like 30 leaves total) and make a new pair for each of the next two mornings. After two days the leaves would be sufficiently dry to expect the final pair to last for a while. I could discard the pairs from days one and two, or perhaps reweave those pair together.