How to make glass marbles
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To make glass marbles using a bench torch or a Map Gas burner, (make sure it says
brazing fuel) (the Map Gas is available at most hardware stores.) this technique is called lamp work. First
selecting a glass rod approx. 6mm in diameter gently heat the tip of the rod (to prevent it from breaking) and
then gradually start adding more glass (from which ever rod colors you choose, this is called a "gather"). In
order to make the marbles round use a graphite mould. This mould is a circular convex shape (or in other words,
1/2 round) with a handle. To make them round you place the hot "gather" in the mould & spin the rod between
your thumb & the first 2 or 3 fingers in a back & forth rhythm.
All the time that your "gather" is in the heat you must make sure that the
"gather" in not too cool or too hot. Keeping the glass in the "Blue" part of the flame and keeping the gather
an orange-red glow. If the glass should become too hot it will "flare" this is called "Soda Flare". It will
turn a bright glowing yellow and can even turn a glowing white & become drippy or even runny.
When you have enough glass gathered to produce a nice round marble you can attach
a punty (another smaller rod) to the opposite end from the main rod & pull the glass & twist it at the
same time. you then remove the punty & reshape the marble.
Once the marble is again a nice sphere (round) transfer the marble to a punty. To
transfer it you heat both places (one on the marble & the tip of the punty) making sure that either the
punty or the marble is at a cooler temperature. Look at the glow in the marble & the punty. The marble
should be glowing bright orange & the punty a cooler red. Or after heating both pieces you can tap the tip
of he punty on a marver (a flat piece of graphite, stone marble, or metal for shaping), doing that will make
sure your punty is cooler than the marble. You will want to remove the punty from the marble right away. Hold
the punty & give it a sharp tap, the marble should fall off the punty into your mould, quickly fire polish
the pontil (the place where the punty touched the marble). Then turn the marble out of the mould into torn up
small pieces of ceramic fiber blankets made into a nest, but cover the marble well. (Available through kiln
& glass suppliers.) You can anneal the marble later, however it is best to turn the marble out into a kiln
holding at the proper annealing temp..
Please remember putting the marble in the blankets too hot will leave marks on
the marble, putting it in between the blankets too cool will surely cause it to break. You want to blanket it
just as the glow wears off. DON'T PEEK! Wait several hours before looking otherwise you'll ruin your marble by
thermal shocking it. In other words the cooler air in the room will cause it to break! Some times it can happen
anyway within a day or a month even years later the stress in the glass can cause it to break in two if not
To anneal means to make toughen by heating then slowly cooling. Moretti glass
anneals at 968°F. If your marbles survived the blanket nest the you can place them in a small kiln & slowly
bring the heat up to 968°F (just above 950 on your pyrometer should work) & hold it there for at least an
hour or more. Then very slowly cool to room temperature at no faster than 300°F per hour.
Be patient you will soon be a glass artist & who knows maybe you'll have
people who are collecting marbles you made!
That being said .........go & make some contemporary hand made
Tips on marble and bead
Co Efficient of Expansion:
Don't mix glass with different co-efficient of expansion (COE). It will just
break up. This is due to glass such as (Moretti 104 c.o.e.) heating and cooling at a different rate than say
Bullseye which is 90 coe. The coe can be no more than 1 point in difference.
There is more to it than that but, it's sufficient to say don't mix different
© 2002 M. Bolser, All rights reserved