Fused Bottle Glass Fritballs

bottle glass frit balls
Cobalt Blue bottle glass frit balls.

Lately I’ve become enamored of working with frit balls. I had no idea how fun and addictive these things are! Maybe because they look like unnaturally colored caviar or tiny marbles, who knows, but they are pretty cool. First though, you have to make them.

Making the Frit

The first step, obviously, is to make the frit. There are several ways to make frit, the most obvious one is to smash broken glass into even smaller pieces. This is certainly an acceptable way to do it. There are several frit making contraptions/pistons available on the market. They all make relatively small portions of frit at a time, which is fine. Let’s look at some other ways of making frit:


Heating bottle parts and then quenching them in cold water is a quick way to make a lot of frit and of keeping it relatively clean and dust free. Guest blogger Beverly Frey wrote a comprehensive tutorial about the various temperatures and resulting frit sizes for us last year. There are some safety measures that must be taken as the heat and potential splashing can be dangerous. Use common sense and work with a partner. Bottle Glass Frit Making


If you have a bit of mechanical prowess you can make a mechanical frit maker using a garbage can and a garbage disposal. The resulting contraption makes vast amounts of frit in a very short time. One of the advantages is a very uniform range of frit sizes.

disposal Frit maker
Frit making machine, affectionately named Chewy

Unfortunately, it is also quite dusty and the resulting frit is laced with metal shavings that have to be removed with a strong magnet after grinding. The black tube on the top of the lid connects to a shopvac with a water trap to keep down dust. It’s always important to also wear a respirator when using Chewy, as well as hearing protection, and safety glasses (it’s an exciting process!) Here is a quick photo of the spectrum of sizes produced with this method:

Sample of frit size spectrum from Chewy
Sample of frit size spectrum from Chewy


For smaller (less than 5 lbs at a time) batches of frit, I use a tyvek sheet and my handy smasher. This device was made for me by a local welder, it’s essentially a solid steel block welded onto a pipe. The pipe is long enough I can stand straight, while lifting and dropping the smasher straight down onto the glass. This helps avoid any repetitive impact on my wrists and hands. Simply fold the glass into the folded tyvek sheet and smash. The resulting frit is of quite varied sizes, the larger pieces may need to be filtered out and resmashed.

Filtering the frit

Most frit making processes result in multiple sizes of frit in the same batch. It’s often a good idea to filter the frit into uniform sizes to make it easier to use in multiple projects. Depending on how much frit you are making, you may want to use a set of frit sifters, or, if you are making large volume or concerned about more accurate size separation, consider geological sieves.

Filtering is a dusty, messy business, take precautions for dust!

Washing the Frit

Your filtered frit will probably be coated with fine glass dust (unless you are using the heat method). Fine glass dust can cause devit on your frit pieces when you fuse them into frit balls. To clean them, you would use a sieve/sifter one size smaller than the particle you are washing, load the frit in and swish it through hot soapy water, then through clean water. Pour the wet frit out onto paper towels or fine weave toweling over newspaper to dry. When the frit pieces are dry, pour them into a clean storage container.

Fusing the Frit into Balls

Once your frit is dry, you can fuse it into frit balls. The idea here is to spread out the frit pieces, heat them quickly to a fusing temperature so the frit pieces melt and round into tiny balls. Since the pieces are so small, and we will be using them for other projects later, it’s not necessary to anneal.

Spread the frit across a prepared kiln shelf. I prefer to use a kiln washed shelf rather than paper for this process as it’s easier to sweep the tiny frit balls up off a shelf after firing.

cobalt blue frit chunks
Cobalt bottle glass frit before firing

I spread the frit pretty thickly on the shelf. If you are concerned with multiple frit pieces fusing together and making globs, you may want to spend a little extra time spreading the frit out more evenly.

Firing schedule for Bottle Glass Frit Balls:

500/hr to 500 h 10 (this is to evenly heat the kiln shelf)

500/hr to 1535 h 3


If your frit balls don’t bead up to be round on the top, you may need to go hotter. If the frit balls are all heavily devitrified, you may need to lower the top temperature.

Cobalt Blue Frit Balls
Cobalt Blue Frit Balls

After the kiln has cooled to room temperature, use a soft paintbrush to sweep the frit balls into a container. I use a 3″ x 5″ card to scoop them up. The sweeping will cause some dust to rise up from the kiln wash on the shelf, so wear a mask for this part too!

Washing the Frit Balls

After fusing and sweeping, your frit balls are probably going to be a bit dusty again. Wash them using the same method as washing frit pieces and store in a clean container until ready to fuse into a new and amazing project.

I’ve found if I keep some clean frit pieces on hand at all times it’s an easy thing to sprinkle a few pieces on the kiln shelf around regular fusing projects. This helps fill empty space in the kiln, and the quantity of frit balls adds up quickly!

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