Why Is My Fused Glass Sticking to the Mold? 5 Things to Check

Glass grabbing the mold is frustrating, but it's usually easy to fix. Here are five things to check.

1. Not enough mold release

For a first prep, use 3–4 even coats of ZYP BN spray, letting each one dry thoroughly. Change the angle of your spray so you reach every surface, especially any centre post or inner shape. With ZYP, it's better to have too much than too little.

2. Sharp points pressing into the walls

If a pointed piece of glass presses straight into a sidewall or an inner shape, it can grip and make removal difficult. Keep pieces relatively flat and turn points away from the walls.

3. Firing to contour temperatures

Contour fusing is the riskiest range for sticking, especially on the middle of the mold. The glass isn't hot enough to flow, so sticking is a greater risk. Aim for a true tack fuse or a full fuse.

4. Lid elements overfiring

Lid elements send directional heat, so a "tack fuse" can turn into more of a contour result. If you fire with lid elements, bring your top temperature down slightly and fire a test sample so you know your kiln's real tack fuse temperature.

5. Kiln wash in a deep, detailed mold

In deep molds with fine detail (like the free-standing dog paw), kiln wash leaves more texture and the risk of sticking is much greater. ZYP gives a cleaner finish and an easier release.

Get the full instructions

Find the prep steps, glass weights and firing schedules in the casting mold guide, the Stand Up Tree guide and the Dog Paw guide.

Show me what you make!

I would absolutely love to see what you create. Tag me @themichellefrost so I can cheer you on and share your work.

Warmly,
Michelle