HotPot 3- HotPot Q & A

During our demonstration of the Hotpot microwave kiln wegot several times the next two questions.


And it where exactly the same questions I did have when I started to use the HotPot microwave kiln.

Where stands COE..  in fusing glass for?

COE stands for Coefficient of Expansion and is used in the world of glass fusing and a compatibly code.

If you fuse glass always stick to glass with the same COE code.

For example if you put COE 90 and COE 96 in a design and fire it in your HotPot or fusing oven the difference in expansion will make the glass crack.

This will happen when the glass expands during firing or during the cooling down period when the glass contracts.

At the same time it tells something about the hardness of the glass. The lower the number the harder the glass. For example a ordinary bottle has a COE 38 code and a lamp worker uses much softer glass like COE 104.

Can I use the glass that I’ve in the barn in the HotPot?

The problem with fusing 'found' glass is that you have no idea what the COE is.

So it isn’t recommended to use this with the glass supplied in the HotPot starter pack.

Hope this will help and if you got more questions about the Hotpot microwave kiln let me know and I’ll do my best to answer them.

Fred Hebing

HotPot 2-Types of glass-Dichroic

We came in contact with dichroic glass through a new fun way of glass fusing called HotPot.

Before I'll go into that a small introduction to Dichroic glass, and the many ways of using this beautifull material.



Dichroic glass is glass containing multiple micro-layers of metal oxides which give the glass dichroic optical properties. This high-tech optical coating selectively reflects certain wavelenghts (colors) of light and allow the remaining wavelenghts to transmit through.

This effect is seen in nature in opals and peacock feathers.


The word dichroic means two colors, which refers to transmitted and reflected color.Multiple ultra-thin layers of different metals (gold, silver), metal oxides (titanium, chromium, aluminium, zirconium, magnesium) and silica are vaporised by an electron beam in a vacuum chamber.



The vapour then condenses on the surface of the glass in the form of a crystal structure. This is sometimes followed by a protective layer of quartz crystal.

The character of dichroic glass is its changeability and it can be used in differend ways.


Dichroic in fused glass application;

Mix of dichroic glass

Fusing dichroic glass not only produces captivating effects, it eliminates all the vulnerabilities like scratches, damage from solvents, oils, flux and adhesives.
The fusing process moleculary binds the glass and the coating materials.





Reflective colors difficult to perceive on clear glass will intensify when fused onto a colored background.

Clear glass offers versatility as it can be fused with Dichroic either up or down.

When fused  Dichroic side down, the coating will be encased in a layer of clear.

When fused Dichroic side up, a soft metallic effect is achieved.


Leaded glass application;

Dichroic used in dragonfly wings

When making a glass panel in the Tiffany or lead came methode that includes Dichroic glass, use a glass cutter without oil and score the glass on the uncoated side.






The coating can be protected from soldering and grouting phases by covering it with low tack tape or contact paper that is easily removed when finished.

Lamination applications;

Cabouchon jewellery by F. Hebing

Some Dichroic jewels and bevels are made by laminating the clear bevel to a coated sheet of thin float glass. This process layers the coating between the glass and is in this way protected from the dangers listed above.
This kind of glassfusing is easy to do in your own microwave, int's known as HotPot.
I'll explane how this very fun process goes in a nex post called "HotPot Norge".


Fred Hebing