Most glass shops will melt clear glass in their furnace. Some places will have dedicated pots of various colored glass melts, but this is less common. For this reason, glass color is applied to clear glass using different methods to achieve varying effects.
The colorant used in glass are metal oxides, rather than traditional pigment. Metal oxides are used because they can withstand the high temperatures (2000+degrees) required to create glass work.
The most straight forward way of color application is to use crushed up glass color. This can come in the form of powder and frit. I buy most of my color from Olympic Color Rods, and they have a link here that shows you the different grains of frit available to purchase. The great thing about powders and frit is that it doesn't require preheating, and you can achieve a lot of different effects, even within the same color, just by switching the frit size.
Above, you can see my friend Joe rolling yellow frit onto clear glass. The color sticks readily so long as the surface of the clear glass is hot enough. Notice how the yellow turns to orange from the heat. Yellow looks orange, reds look brown, black will often reduce to silver, and some white will turn clear when hot! In most cases, the glass will shift back to its original color when it goes back to room temperature.
Powder has the added advantage of being able to sift.
These are some examples of my work using frit and powders.
Years back, I created flattened pieces of colored glass with frit and powders to create mosaic-like patterns on my work. I cut the rounds with a tile saw, and created a pattern that can be heated in the gloryhole to in order for it to be picked up onto a pipe.
Another way of applying color to glass is to do a color overlay. Overlays are done using solid rods of color / color bar. Since these rods are larger than frit, they need to be preheated in a kiln or garage before using, or else they will break.
Below, my assistant, Dave brings me my color in the perfect heat and shape so that I can easily drop it onto my clear bubble and shaped on the marver. The colored glass is cut using diamond shears. Overlays will give glass an even color to the form, rather than a spotted look that frit will typically create.
By changing the amount of color bar used, different results can be achieved, such as creating color fades.
Here are some other examples of works of mine that utilize color bar.
I like the organic nature of applying blobs of color rod onto glass. The results can be a bit unpredictable because different colors move at different rates when you are working it, but I love the overall effect.
Applying color to glass can be tricky. If you want to know more about the techniques involved, let me know. You can also click Here to read my blog post about color or Here to take a look at how I organize my color! I hope this gave you some insight into what goes into my designs!
Thanks for getting this far in the blog! As you probably know, I'm the middle of moving out of SF so everything in my life is not at the usual level of homeostasis, which is why my posting schedule and work schedule is a little whacky. But I'm still working on creating content ... just slower than normal. Anyway, thanks for reading and thanks for your support!