I’ve seen some high-end art gallery pendulums over the years which use an ultra-fine (almost dust-like) glass sand bead for higher resolution images and less friction for the swinging pendulum movement. The sand that appears to come with Sisyphus is coarser, almost like a grade above play-sand, but not to the grade I recall seeing in some of these gallery-caliber pendulums. Has anyone upgraded their table with a finer grade of sand? Any concerns about trying a finer grade of sand? One I’m looking at is this one.
I've tried glass beads in the past, although perhaps not as fine as what you describe. The reason I chose to stay with sand (silica), is that glass beads are spherical and therefore have a lower angle of repose than does silica, which has a more irregular shape. This allows for steeper dune walls and greater detail. But I welcome people trying other particles and reporting their results. Some guidelines:
Of course, all of this is subjective and it's fine to try other stuff on your table - though I would stick to solid particles - no liquids :).
Thank you for the feedback! There is some interesting info in your reply. I’m going to try the fine white pendulum glass sand I posted above, as I suspect it’s the same as what I’ve seen in gallery pendulums. (I’ll try it with the bearing on a dinner plate to start before I rush to vacuum out the original sand.) This sand is bright white from what I recall, and very fine texture but not quite dust-like. I will post pictures and my feedback if I decide to use it in the table.
I did try the ultra fine sand for a few weeks. This sand is fascinating because its particles are so small they are invisible to the eye (like talcum powder) but have enough mass they don’t float like dust. They sink like sand. It behaves almost like wet cornstarch or a peculiar liquid. Anyway, some photos are attached comparing the detail. This sand had the following problems:
1. You need to remove or gently crush some globs that form in the bag (I didn’t, which is why my track looks chunky).
2. The sand contains microscopic bits of iron (probably from the manufacturing process) that cling to the magnetic ball and eventually need to be removed.
3. It is so fine that mistakes and ball-tracks in the design show, that aren’t supposed to show.
4. It is so fine it looks fake, like moon dust or the playa dust of Burning Man. Designs are crisper and sharper, though.
it was an interesting experiment. White play-sand about the consistency of table sugar seems to be the best look for the table.
Thanks very much for posting your findings! Super interesting. As for the iron contamination - you can use the ball itself to collect it - when it has grown iron filing "sideburns", gently dab them with a wet paper towel to coax the filings off the ball while it is couple to the magnet (or the filings will drop off into the sand). Repeat this cycle of running / iron dabbing until the iron is gone. The increased detail is pretty amazing - but for me, the cost is too high in aesthetic terms of it not looking like sand dunes. This fits with my current understanding that there is a physical limit to how small the particles can be, beyond which they no longer behave like sand.