Frequently Asked Questions
Frequently asked questions about the process of sun-melting glass, answered by Bretwood Higman, the inventor of Sundrop Jewelry
Where did you get this idea?
To our knowledge, no one else does this. I invented the technique when I was 13 or 14 growing up in Alaska. I was messing around with melting rocks and glass, and thought the little droplets were kind of cool. Someone else suggested I could make them into jewelry, so I did.
How do you get the colors in the glass?
We have a few different techniques for making multi-colored Sundrops:
- To make striped Sundrops we start with colored glass and mix them together by fusing strips of different colored glass together in an electric kiln, then twist the strips into spirals. Then we use the lens to melt this stock into drops.
- We also use stained glass that contains streaks of different colors. There is color variety within each Sundrop made in this manner, but they do not usually show the same defined pattern we get from the first method.
- Another method we use is to take two glass rods, put them side by side and wrap a couple rubber bands around them to keep them together. It's low tech, but this allows us to melt glass from both rods simultaneously, creating a half-and-half color like High Tide.
- The last trick we use involves a 'filigrana' glass rod. These rods have a central core of a color, surrounded by clear glass. So long as the central color is dark enough, that color will absorb enough light to heat up the surrounding clear glass as well, allowing us to make drops just like any solid colored glass.
What materials are used to construct the jewelry?
We use stained art glass or recycled bottle glass to make the droplets themselves. All wire and ear hooks are hypo-allergenic sterling silver, and the sterling silver wire is 100% recycled. Necklaces come on sterling silver chain. Body jewelry findings are internally threaded hypo-allergenic stainless steel.
How hot is the focal point?
This is a more complicated question than you'd first think. The heat produced depends on how much light is absorbed and converted to heat, and also on how much heat is lost through conduction or other processes. If the light just focuses in the air, there is very little to absorb the light (air is clear) so almost no heat is generated. Clear glass will heat up a little, but not nearly enough to melt. Colored glass melts nicely, though very dark colors can heat up a bit too quickly and tend to boil. We like to work glass at between 1400° F and 1800° F (generally around 1600° I think). When we focus on a black rock, which both absorbs lots of light and insulates well enough to reduce the amount of heat that leaks away, the temperature is over 3000° F, enough to melt steel (2700° F).
If I stick my hand under the lens, will it burn me?
Yes! Our magnifying lens can focus enough light to create a 'hot spot' of more than 3,000 degrees Fahrenheit.
Have you ever burned yourself?
Yes, many times, but never too badly. Most of the times we do burn ourselves, it happens because we accidentally or forgetfully touch glass or one of our tools that is still too hot.
How hard is it to make Sundrops match for earrings?
We make many drops of the same color without worrying about the precise size and shape, then select matching pairs. Each Sundrop is uniquely hand crafted, so no two are exactly the same.
Where did you get that lens?
The original fresnel lens I got was from Edmund Optics. I just ordered it through the mail. They have since discontinued the large size lenses we use, and we have also bought lenses from GreenPowerScience.com.
Is the lens glass, or plastic?
What are those lenses usually used for?
These particular fresnel lenses are designed for solar concentration, like what we do. However I don't know of craft or industrial purposes for which these are used. Many people just play around with them. Fresnel lenses were originally developed for use in lighthouses.
Are the drops made of glass, or just plastic?
Glass; plastic just catches on fire. We use soda-lime glass, primarily fusable sheet glass from Bullseye Glass. We also melt recycled bottle glass, lampworking glass, or whatever else we can get ahold of. We don't generally use Borrosilicates though, because they have very high viscosity and don't flow into a drop very easily.
How do you shape the glass?
The glass is shaped only by surface tension and gravity. We don't use a mold. The glass cools in the air, not in water or anything else. If we let the glass fall into the water, it might form what is called a "Prince Rupert drop". Prince Rupert Drops tend to be misshapen, and have unusual structural properties. They are very strong, so if you hammer on them they do not break, but if you break off the thin tail the whole drop explodes into tiny slivers of glass. They can also do this spontaneously, so they wouldn't make very good jewelry. But I digress...
To create the teardrop shape we heat a lobe of glass and let it drip into the air. It cools as it falls, and (hopefully) stops above the ground, suspended from a strand of glass. See our videos demonstrating the process.
Can you make bigger drops?
Somewhat bigger, given dark glass with a low melting temperature. However the area of the focal point is only about one centimeter across, so you can't make anything more than a couple of inches long.
How fragile are Sundrops?
Surprisingly strong. Most of the time, they will not break if dropped, even onto concrete. However, sitting or stepping on them may break them.
Is it hot working under the lens?
All the light that passes through the lens is focused to a point, so it throws a shadow. However, because the focus is not perfect, and because of infrared re-radiation, my hands can get pretty hot sometimes.
What do you do if it's cloudy?
All the other work involved in making jewelry. The lens creates an image of the sky, so if the whole sky is gray, there is no bright spot, just uniform light refracted through the lens. If the sun is fuzzy, so is the bright focal point. And if the air is totally clear, you'll get the sharpest, hottest possible focus.
What if it's cold outside?
The air temperature only varies by a hundred degrees or so, and that's small compared to the 1500° working temperature, so it really doesn't matter (except to our poor cold fingers). We try to build up enough stock during the warm months so we don't need to melt Sundrops in the winter.