Studio News: Tips for Using Frit Molds


Frit Molds are becoming increasingly more popular, especially with all the new styles of jewelry molds coming out. Getting a beautiful finished project can be tricky at times.

Issue #1: Glass tends to stick; and create sharp daggers on the sides of the glass project. This can happen when the glass separator is getting thin or worn away.

Boron Nitride MR-97 is the answer. It is a versatile product that can also be used on stainless steel molds as well. Think of it like teflon on your frying pan. It will not allow the glass to stick to the mold. Projects pop right out and are ready to wear. You do have to follow the instructions and reapply as directed.

Watch a video on how to use Boron Nitride MR-97.

However if you do get spurs on the sides of your project, simply use a wet hand sanding pad to clean up the edges.

Issue#2: The frit is trapping a lot of air bubbles that you can see in the finished project.

Thats frit for you. Air bubbles will happen, however if you change the soak or hold time based on the size frit you used, you may have better luck. For example, if the mold calls for a 10-minute hold for fine frit, then it might be 25-30 minutes for medium frit and 30-35 minutes for course frit. I dont normally recommend coarse frit for casting molds.

For best results, follow instructions for the frit weight you should add. After filling the mold, brush it slightly away from the edges. Use an underglaze pencil to write the weight requirements on the side of each mold when you get them.

Some other helpful tips when using frit molds:

Never fire your mold more than 500 degrees per hour; and never over 1450 degrees.

Mix your color frit (1 part) with 5 parts clear or water clear frit. Then add a couple drops of water, so that you get a better sense of what the color will turn out like.

Check out these hot new jewelry molds...

Pictured top left: Necklace made with new NEW Nano Beads Mold. Read this project sheet from Colour de Verre on How to use the Nano Bead Molds.

Pictured middle right: Heart Trio Earring Pendant Jewelry Mold.

Pictured lower right: Pillow Pendants Mold. Read this project sheet from Colour de Verre on How to Use the Pillow Pendant Mold with Dichroic Glass.


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Jacqueline H.  •  January 11, 2019
I have bought little fritter molds and produced nice products. I want to tack them to other items... what is the highest temp a little fritter can reach before it starts to melt and lose its definition?
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Deborah A.  •  October 30, 2014
I purchased 3 jewelry molds from Delphi. I have tried two different places to fire them and none have turned out. How to I find out what the exact fire process is for my molds.
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Chandra A.  •  February 06, 2013
@JackiS Yes, you can certainly use the MR-97 on molds that have previously been treated with a primo-primer (or the like). It is recommended that you remove as much of that previously applied product as you can before spraying on the boron nitride spray so that all of the raw mold can be exposed to the spray. Just remember that once you apply the boron nitride spray it will not take the other kind of release anymore, but popular opinion boasts that it is well worth the switch.
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Jacqueline S.  •  January 28, 2013
I just ordered MR-97. I understand about using it to prime new molds for easy glass release, but is it possible to begin using it now on already- used glass molds which have previously been primed with a powdered release agent/kiln wash (the kind you mix with water and brush on, then fire)?


Denise Christmas-Gibson is a glass artist and instructor. Denise owned her own studio for eight years and now works with other studios in helping them with their programs.   After graduating with her degree in Marketing from UCF in Orlando, she became a corporate executive for 18 years. As her children began to grow up, she decided to do something that would allow her to spend more time with her children and provide a creative outlet for her 'inner artist'. Discovering fusing of glass changed her life. She now spends hours a day working with glass, teaching others to enjoy this wonderful medium, and consulting with other studios whenever possible.