Is coconut shell good to produce charcoal for drawing? Does the material that we use to make the charcoal decide its tonal character?
Is coconut shell good to produce charcoal for drawing?
I am sure that will work just fine.
It does depend on the type of shape you want, as the structure of coconut shell is not optimal: it is naturally curved, making it hard - if not impossible - to get nice straight styluses out of it, and it might splinter more easily when exposed to high temperatures, because of the inherent tension.
Does the material that we use to make the charcoal decide its tonal character?
It does, but not a lot. Different source materials have slight differences in pigmentation, texture, and strength. Generally, types of wood are used, of which willow and grapevine are the most popular types for drawing. You will notice larger differences between charcoal and charcoal pencils, than between types of wood.
Drawing charcoal is made in two general ways. One is to start with wood that is naturally in stick form and turn it into charcoal by burning it in a kiln without air. Grape vines and willow sticks are commonly used for that, but DIYers use almost any kind of available sticks, or even lumber cut into sticks. The drawing characteristics of the result are whatever the source wood gives you.
The other method is similar to how graphite pencils are made, only using charcoal instead of graphite. Various kinds of wood can be used to make the charcoal, but that isn't the major factor that controls the drawing characteristics. The charcoal is ground into a fine powder and mixed with a binder, typically a gum or wax. The manufacturing process controls the hardness of the result, mainly by the amount of binder used. Like graphite leads, the hardness is the major factor driving the drawing characteristics. Compressed charcoal can produce darker lines than stick charcoal.
If you're thinking about making your own, you aren't likely to be able to replicate the compressed powder, but you can easily replicate the stick method. You would need to cut the coconut into strips of the desired size, get all of the coconut meat off, and give it plenty of time to thoroughly dry out before trying to turn it into charcoal. They'll be curved, but that wouldn't necessarily affect their usability (straight wood sometimes curves in the kiln).
A bigger problem may be the nature of the coconut shell. It's relatively thin, and is a mat of fibers rather than solid wood. It might not have the strength to draw with (the fibers may also not hold together after it's turned to charcoal). If that's the case, you could try reinforcing it by wrapping a strip of paper around it for strength.
Here's a good article on doing it in a paint can: https://www.sightsize.com/making-charcoal/. The author's experience was that the hardness of the wood made a difference. This video, https://www.youtube.com/watch?v=UpwlnaUwnoQ, covers more detail on the preparation when starting with sticks (the other author started with lumber cut into "sticks"). I couldn't find anything online where people had used coconuts. You will need to experiment, then post your results and any lessons learned. :-)
I tried my hands on making charcoal with coconut shells. I used the technique shared by most of the youtubers where they use a perforated can to cook the raw material(in this case broken pieces of coconut shell). The result was not that appealing in the sense that the charcoal I ended up with was not making dark marks as expected in the paper. Instead, there was grooves on paper. In effect, the charcoal was not soft enough to get disintegrated and absorbed to the paper. Later I tried with a stick of Gliricidia sepium a locally available soft wood. It has excellent blending ability.