Here are some more updates on tinkering with dried and ground-up SCOBY.
The second try, I used some more powdered material. I added water untill it was the had the consistency of something resembling ketchup. I tried creating a hollow cylinder. It extruded nicely through a syringe with a hole of 2,5mm, although a considerable amount of manual force had to be applied. The lack of a consistent path, just freehand with all degrees of freedom, made it hard to produce an even shape. Also, the water to material ratio was way too high and so it collapsed rather quickly and made it into a “blobject”.
The dried result was really strong. It was very difficult to cut up by hand and even damaged my plastic blender housing when trying to regrind it. It also supported weight.
Here’s a video where I first sawed through one side entirely to try to break it.
But to achieve predictable shapes, the water content had to go down. Doing this would increase the required force even more, so I had to enlarge the nozzle diameter.
After this, I ground all the material into a powder again. It is interesting you can reuse it!
This time, I retried the same experiment and made a precise ratio of 2:1 water and the powdered material. This produces a peanut butter consistency that is easy malleable into a shape. But I chose to extrude it, as this would provide insight in wether this could be extruded or not.
The result was much better. Sagging was very limited and it was easier to produce a freehand shape. But still inacurate, due to the material pulling the extruded strand after sticking to the previous layer. Controlling particle size would also help in having an even flow to make it predictable.
There was some shrinkage after drying, but it seems to be uniform as long as wall thickness remains even. This is similar to working with plastics.
The dried cylinder is again really hard and not brittle. It does not break when you drop it. You could definitely make functional, structural, small objects with this as it could handle a load of at least 6kg of force perpendicular on the axis (so on the curved side, the weakest).
The reusability, grinding and remolding or re-extruding, also intrigues me. What could be a nice application for this? Maybe for sending&protecting goods that get sent and transported?
My theory behind the microscopic principle and the strength is that the nanofibres that are arranged in matrices, after grinding, cover a huge surface area. When soaked, each matrix expands and the fibre ends latch into other fibre matrices. When drying, they shrink and so tighten the bond. I’m no chemist or biologist, but I’m curious if someone knows this?
Will definitely do some more experiments!
Note: some pictures aren’t in the right order. Blame my phone