Glassatelier Hebing Efteland's

014 HotPot Norge Glassatelier Hebing Efteland by

Q&A

From HotPotter to HotPotter

 

In this blog you will find HotPot related tips, advice and how-tos to improve your glass fusing and have an enjoyable time!

 

Feel free to drop us a question, if it's been on your mind, chances are someone else has been wondering about it too and you'll be doing everybody a big favour :o)

By HotPot Norge, Feb 2 2013 10:00AM

Bubbles can be caused by many different things.

Uneven stacking of glass can result in air trapped between layers. To prevent this from occurring, check the placement of all the glass pieces to insure they are sitting properly on the base. If possible fill up the small openings between the different glass pieces with a clear glass.

Second, check the glass prior to fusing. Some glass may already contain bubbles inside, which may or may not affect the outcome.

By HotPot Norge, Jan 16 2013 01:06PM

Most Hotpotters know that glass can break due to rapid, uneven temperature changes.

Mostly during cooling down and sometimes while firing.


This is known as thermal shock.


Why this happens may not be obvious.


When solid glass is heated or cooled unevenly, the part of the glass that is heated will expand (or contract if cooled). The glass that isn’t changing temperature stays the same size.


This uneven expansion creates a lot of stress inside the glass. If the stress is strong enough the glass will break. And that is called thermal shock.


A good example of this you can see in the picture.


Here I mixed glass with different thickness and in combination with rapid firing, it gave me an S shaped crack. The thinner glass got hotter faster than the thicker glass and causes thermal shock.


I repeated the experiment with less heat over a longer firing time up to 10-12 minutes and the results were much better. The pieces came unbroken out of the HotPot, that was already a big improvement.


When I came back to the studio the next morning still some thermal shock had occurred during the night.


Overall I can say that with lower heat and longer firing times, it is very possible to fuse glass with different thicknesses and from different suppliers together with a success rate of +80%.


All the glass used in this test had the same COE.


S shaped crack result of thermal shock.
S shaped crack result of thermal shock.
Different thickness of glass fired with a lower wattage.
Different thickness of glass fired with a lower wattage.

By HotPot Norge, Jan 20 2012 11:00AM

Dichroic glass is glass containing multiple micro-layers of metals or oxides which give the glass dichroic optical properties.


The main characteristic of dichroic glass is that it has a particular transmitted color and a completely different reflected color, as certain wavelengths of light either pass through or are reflected. This causes an array of color to be displayed. The colors shifts depending on the angle of view.



Invention

Modern dichroic glass is available as a result of materials research carried out by NASA and its contractors, who developed it for use in dichroic filters. However, dichroic glass dates back to at least the 4th century AD.



Manufacture

Multiple ultra-thin layers of different metals (such as gold or silver); oxides of such metals as titanium, chromium, aluminum, zirconium, or magnesium; or silica are vaporized by an electron beam in a vacuum chamber.


The vapor then condenses on the surface of the glass in the form of a crystal structure. A protective layer of quartz crystal is sometimes added.


The finished glass can have as many as 30 to 50 layers of these materials, yet the thickness of the total coating is approximately 30 to 35 millionths of an inch (about 760 to 890 nm).


The coating that is created is very similar to a gemstone and, by careful control of thickness, different colors may be obtained.



Artists

Dichroic glass is now available to artists through dichroic coating manufacturers. Glass artists often refer to dichroic glass as "dichro".


Dichroic glass is specifically designed to be hot worked but can also be used in its raw form. Sculpted glass elements that have been shaped by extreme heat and then fused together may also be coated with dichroic afterwards to make them reflect an array of colors.


By HotPot Norge, Jan 6 2012 11:00AM


A microwave kiln is a device that crafters use to fire small art projects in a microwave oven.

While some crafters use it to fire ceramics or process precious metal clays, the most common use is to fuse small pieces of glass as part of the jewelry-making process.

This type of kiln has numerous benefits — namely cost, time efficiency, and convenience.


Microwave kilns are cylindrical in shape and consist of a base piece and a cover made from a combination of ceramic and refractory board. Refractory board is a material that can withstand high temperatures and act as an insulator.


To use a microwave kiln, place the fiber and thin fire paper in the middle of the base piece.


Put the glass on top of these papers and place the base with the glass in the middle of the microwave on the blocks that are delivered with the HotPot.

These blocks are necessary to elevate the HotPot from the bottom of your microwave.

By using the blocks the generated heat stays in the HotPot.

It prevents thermal conductivity from the HotPot into the microwave and by this protects your microwave against overheating.


After placing the base I put the top part of the HotPot on its base.

I do this at this stage so I can see if the glass layers are still in the way I wanted.


Activate the microwave and run until the piece has been completely fired. Once the process is finished remove the HotPot immediately from the microwave and leave to cool on a heat-proof surface.

A bathroom tile is perfect for this.


There are a number of benefits to using a microwave kiln.

It is significantly cheaper in price than a traditional kiln, and it requires a great deal less energy to operate.


While the firing time varies based on the size and type of the project and by the wattage of the microwave, the process is generally brief, typically achieving fusion in 8 to 12 minutes.


We recommend maintaining a separate microwave dedicated solely to kiln projects.

To minimize the potential for accidents, it generally is recommended that all microwave kiln users thoroughly review manufacturer instructions before kiln use


By hotpotnorge, Jan 5 2012 10:10AM

Recently we encountered a very fun new thing that's happening in the world of glass fusing.

It's called HotPot and you can fuse glass in your own microwave, how about that.


With the use of the nice dichroic glass types out there it's possible to make very nice fused personalized jewelry in a very easy way.

At the moment we are practicing this and the results are very satisfying from the start.



The HotPot is a small kiln that is designed for use in a microwave. When placed in the microwave this kiln should be elevated from the microwave floor. The kiln comes with some blocks for this purpose.


The only other thing to prepare before using the kiln is to put fiber- and releasing paper in the HotPot and you're ready to go. These papers prevent your glass from sticking to the kiln and will give the piece that you're designing a smooth finish on the back.


After this 30 second preparation, the real fun starts - designing your jewelry.

It is much easier than it sounds, more or less placing several pieces of glass on top of each other.


And there are so many nice type of glass out there.


Another nice thing to do is to incorporate milefiori or precut shapes in the design you're making.


To make it more personal, cut your own glass shapes. Remember, when cutting glass cutting for use in the HotPot, always do it with an oil free glass cutter.

When cutting dichroic glass, always cut on the back side of the glass so you don't damage the layer of dichroic film.



There's even a glue to stick glass pieces together because stacking glass is slippery business, and they can slide.


It happened several times while placing the kiln in the microwave - glass falling of each other by the smallest bump or when carrying it on the tiniest angle.


How unfortunate it happened again, maybe we should start using the glue?


We the glueless people (or are we the clueless people?) gently place the bottom part of the Hotpot with the assembled glass pieces, on the blocks in the center of the microwave

.

And be even more careful when placing the Hotpot lid on. Most of the time we end up lifting the lid just one more time to make sure the glass didn't shift. (Remember glue less)


All set and done. Time to start the microwave (750-1000 watt) and let it go for about 5 or 6 minutes. Time to have a peek. Put on your gloves and lift the top up far enough so you can see if the glass is melting. If not melted far enough give it some more microwave time.


You can look every 30 seconds if you want till you see a nice orange mound of glowing glass.


Done that's all to it.


Carefully remove the kiln from the microwave and place it on some heat resistant tiles (leftover tiles from your bathroom will do the trick) to protect your worktable surface.


Let the kiln cool down totally and do not remove the glass till after the cooling down. Doing so early will cause thermal shock to the glass and it will crack.


That's all that there is to it, time to have a drink and maybe prepare your next piece.


For more info on the Hotpot visit www.hotpotnorge.com



Fred Hebing