This bizarre density toy just got an upgrade

PLA in acetone makes a really odd smell. The sponsor is KiwiCo: get 50% of your first crate of a monthly subscription here: www.kiwico.com/stevemould

So glad you found a SOLUTION!

I don't think I have ever heard this many names of plastics and oils in 13 minutes in my life

kids: doing an interesting kiwico project and having fun father: mixing liquids and beads in a bottle while slowly losing his sanity

Never thought I’d hear Steve Mould lamenting not getting “the good stuff from Brazil”.

The rosewood soaks up the liquids, mostly moisture (water) and becomes almost 50% more dense. Brazilian Rosewood (dried) has a density of 0.95g/cm^3 so it barely floats even dry.

Consider just putting a single bead of each type in the toy. The fun is seeing the types of beads settle at different points as if by magic and just having a single bead of each type will do that while avoiding the particles getting stuck on each other. It would look a little less impressive in some respects, but I think there would still be a nice wonder to single particles floating in the middle points of a tube of liquid.

If you could make glass "beads", you'd be sorted! I imagine that you could start with a glass tube, melt the ends together, and vary the density by varying the length, which in turn varies the enclosed volume of air. The glass would be unaffected by any of the liquids, and they would also look very similar, enhancing the mystery for the uninitiated viewer.

Paraffin is a messy term whose meaning has changed with time and geography. Historically it was synonymous with the word "alkane" in general (an alkane is any saturated hydrocarbon, that is, it's entirely made of carbon and hydrogen and it has no double or triple bonds). In the US it mostly means paraffin wax today - saturated, straight chained alkanes with ~20-30 carbons that are solid at room temperature and make nice candles. The paraffin oil you've got is essentially a purified version of kerosene that (should) only contain the straight chain alkanes with carbon counts in the teens. And there's surely some crusty old materials scientist somewhere who calls all alkanes paraffins still, because there's always someone like that...

It won't be Brazilian Rosewood, which is illegal to buy and sell, unless you can find it reclaimed, which is both expensive and rare, or you buy it on the black market. It will be East Indian Rosewood, most likely, which is still legally available. The two do have different densities (and sound qualities).

8:52 That actually looks really cool just on it's own. Now I'm thinking about those ships in bottles. You could turn the bottle sideways and have a little plastic ship that floated on the bottom layer.

1:48 Remind me never to order a pint of IPA if the barman is a chemist...

Wood is porous. Its density is dependent on what you saturate it with. wax or epoxy coat it?

Hey Steve! Wonderful demonstration. Couple of things: 1) 3D Prints are notoriously porous. It looked like your prints only had 2 perimeters, which would probably cause liquid to seep into the hollow cavity, affecting the density. Increasing perimeters to 4 or 5 should help, but in my experience I've had to coat my prints in epoxy to get true water-tightness (though that would throw off your density calculations and epoxy probably won't play well with your chemical cocktail). 2) I'm sure you considered this, but the squareness of the beads is probably causing them to lock up together instead of floating past each other. Maybe chamfering at least one side of the cube's corners would help them slide by each other?

I'm honestly more impressed by version 1.0. The fact that the liquids stay clear all the time makes for a stunning effect, whereas you know right away what is going on with the 2.0 one.

That notebook and pen set is soooo legible, great choice

Pla is hygroscopic, which may account for the shifting bead density over time.

You can make cubical beads rounder so that they do not stick together and also reducing amounts of beads will help

2:36 Seriously, that stationery flex though. I think I see a Rotring, a Mars, and a Kuru Toga, plus that lovely eraser and straightedge. 😳

Colored mechanical pencil lead just blew my mind