The main problem I had with my previous ferrofluid test was that the magnets would repel each other enough that I was not able to achieve a single, solid object. After (mostly) cleaning the ferrofluid off of my magnets, I carefully removed half of the magnets and a washer, replacing them with a bit of Sculpey that weighted exactly the same. I pushed half of the magnets into the Sculpey, and then used them to hold another 17 magnets “outside” of the main body. This spacing keeps them far enough apart that they do not repel each other, and the Sculpey fills in the areas between the magnets.
The Sculpey will probably lose some weight when it is baked, but I’m counting on the ferrofluid to allow me to adjust the weight of the hanging object suitably. I don’t want to test it with ferrofluid until after I bake the Sculpey and coat it with black spray paint. The punk potato has a magnet with a plastic cap on it, so I needed to determine the lowest possible temperature that will harden the Sculpey without demagnetizing the magnet or melting the plastic cap. (Currently, the “punk potato” is right at the lower weight limit for successful levitation.) As the lowest curie temperature I could find for common rare-earth magnets was 310 °C, the plastic (which I assume is ABS, with a melting point of 105 °C, (or 220 °F) is my limiting factor. I set the oven to 215 °F and wrapped some tinfoil around the plastic in an attempt to protect it.
When I showed it to my wife she closed one eye, tilted her head, and said “Weird”, so I know I’m getting close to the aesthetic I’m aiming for.
After buying some strong rare earth magnets I re-tried my ferrofluid levitating sculpture. The main problem is that the ferro-fluid moves to the poles of the magnets (top and bottom, with gravity favoring the bottom) and does not surround the sides of the magnets. It was also hard to get enough small magnets to fit under the main magnet (as they repel each other), so I had to include a screw in the middle to get the weight correct.
Note: Working with Ferro-fluid is dirty and messy. If magnets snap together they can throw dark oily fluid which stains just about anything. Be sure to have lots of paper towels on hand, jars/shields under/around everything, and don’t work in a nice room. Dish detergent and abrasive scrubbing will eventually get it off of most surfaces that are not porous. Wear disposable rubber gloves and use disposable pipettes. Wear disposable clothes. Don’t use any of your wife’s kitchen appliances or instruments that you can’t afford to replace.
Update: After floating under the magnetic levitation for 24 hours, the ferro-fluid became much less “spiky” and eventually the drops at the end of the magnets became spherical.
Also, cleaning ferrofluid from a magnet is almost impossible.
Test 1 was not a failure. A Failure would have involved getting ferrofluid all over my clothes and/or workspace. However, I was not able to get enough ferrofluid to “stick” to the magnetic mount to get the weight up to the 74g needed for proper hovering action. Gravity pulled the ferrofluid down to the bottom of the screws and it started to drip off much too soon. It looks like I will have to augment the upper magnet with magnets on the lower parts to get the ferrofluid to surround the hovering part of the sculpture.