fusing into small molds

[marV]

I have some small pod molds which were a gift included with glass I purchased. They would be small castings I guess. One has 6 different shallow small shapes for jewelry about 1/2″ deep. Two are a bit larger – about 3″ wide and about 1/1/2″ deep. Do I filll these to the top with frit or small pieces of glass level with the top of the mold or add enough above it to allow for slumping into the mold? What fusing schedule do I use – full fuse or? I have a Jen Kiln with side and top elements.

 

 

[Janice]

I have a new small jewelry casting mold, a teardrop shape with a raised area for a hole.  (My first experiment with frit)  I filled it with frit and when finished, it had “burrs” all around the edges from the frit.  I fired slowly to 1600 degrees and then left it until cool.  Did I not fire it hot enough or what?  I’m new at this.

Thank you,

Jan

[Stephen Richard]

What you are doing with these moulds is open face casting.  So you need to take the glass up to fusing temperature at the least.  A little experimentation will help determine whether higher temperatures are required.

The moulds need to be filled with sufficient glass to form a piece at least 6mm thick if you want to avoid the needling.  Find out the volume of the space in the mould in cubic centimeters, then multiply by 2.5 and that will give you the number of grams of glass needed for the mould.  Normally, the glass frit will be heaped.  The finer the frit, the higher the heap; also the higher the temperature required to get a clear result.

Stephen Richard

blogs at: http://www.verrier-glass.blogspot.com/ and  http://www.glasstips.blogspot.com/

[marV]

I was at Bullseye Glass in Portland and we made one larger open face mold for casting glass. In order to find out the volume of glass needed for the mold. The instructor had a measuring cup filled with water, then filled the mold to top with water. The amount of the water remaining in the cup was noted and the difference was the amount in the mold. This gave us the volume of the mold. Then we weighed the amount of glass needed to fill this mold. We used billet solid glass chunks and they extended above the surface of the mold.

I will use this method to find the mold volumes for these small molds. I think I will try small pieces or chunks of glass to see how that works out.

[Stephen Richard]

This is very common with castings.  Most casting requires cold working to remove rough edges and surfaces.  An increasingly fine series of wet and dry sandpapers – use them wet – will quickly give you a polish on the pieces.

Stephen Richard

blogs at: http://www.verrier-glass.blogspot.com/ and  http://www.glasstips.blogspot.com/

[blamdimond]

I had inadvertently had frit over the “hump” intended as the hole, and I believe this caused my pieces to crack…so next time I plan to pile it more away from the hump.

[Author]

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