A few months ago we picked up another set of ice molds. In one of our first posts ever we explored the virtues of a diverse ice program followed by an early exploration of ice spheres. Later, we posted a followup and wrote about making ice shards for taller drinks. Since it has been a while, we thought we could revisit this topic. We still can’t afford to spend thousands of dollars on a Taisin solid metal “melting” mold (at least not one big enough), so we are always looking for new and better designs that use the slow process of freezing shapes.

There are several options available today—many more than when we first explored the idea. We still love the molds from Muji.com but we recently expanded our collection with these by Tovolo. We really like the design, so we wanted to write a few words now that they top our list. We think they beat the Muji spheres for a couple of reasons and are hands-down better than an all plastic design.

First, they are a hybrid of the tray concept and the silicone flexible mold design. The bottom section is made from a hard translucent plastic while the top section forms a flexible lid. You fill to the line, then press down the silicone which forms the top of the sphere by capturing the water and holding it in shape. This beats other tray styles like the Japanese two-piece plastic trays and the ones from MOMA because they are less likely to separate during freezing and aren’t prone to breaking. Both sections are practically indestructible.

In addition to strength, this design captures the water in a way that stops it from leaking out the sides. The tight fit and high walls of the bottom section leaves nowhere for the water to leak out. With the Muji silicone mold, the water inside can sometimes find a way out the side if you don’t get a perfect seal which does happen from time to time.

Finally, the Tovolo molds are slightly larger than others allowing the sphere to better fill most rocks glasses. A bigger sphere means more ice mass which cools better and longer. Un-molding these requires slight warming under running water, but the results have been great, especially with improved technique:

Improved Technique to Eliminate the Egg
No matter which mold you use, we have found a great technique to improve the quality of the result. Instead of simply filling the mold with water, start with a large ice cube. Since we already use the Tovolo silicone ice trays to make cubical ice, we drop one of these into our mold and then fill the rest with water. This does several things. First, it speeds up the freezing process by seeding the sphere with pre-frozen water. More importantly, however, it leaves less opportunity for expansion. Since some of the volume is already solid, less water remains to expand the mold into an egg shape. If you have the Muji mold, starting with a cube will help create rounder spheres every time!