glass colorants

[Terry Gallentine]

I have been experimenting with using lasers to burn images into glass and it has been going well. Currently I am using glass colorants that can be lasered to tint the base glass. The colorant that I have been using is cobalt carbonate since it is probably one of the most potent glass colorants. I have also had some success with manganese dioxide. I was wondering if there is anyone out there that is familiar with glass colorants and most importantly their strength or capability to color glass.

[Barry Kaiser]

Terry,
You might try Mason Stains.
They would combine with melted glass (at the surface) and (hopefully) withstand the temperatures

[danieljanse]

Hi Terry, I mix up my own glass recipes and can give you some info. I love the sound of this unique process...I'd enjoy seeing some pics. How in the world do you keep the glass from heating up at the laser point at breaking?

Potassium Chromate: Green
Iron Oxide: Coke bottle green
Selenium: Yellow
Cadmium-Selenium: Red (got to find the right ratio...also these are NASTY! Need good ventilation.)
Copper Oxide (red or black): blue (Copper plus Black Tin might give copper ruby red.)
- Copper and cobalt are also mixable for a range of turquoise colors.
Gold: Pink (may also require Black Tin oxide for reduction)
Nickel-Oxide: Black-Grey
Manganese and Cobalt can be combined for purple.
Erbium: pink
silver: yellow. might be able to mix this with other colors as well to create a metallic sheen. But, would need a way to reduce the silver...fuel rich flame, sugar, sulfur.
Sulfur alone is ambe, and stinks.
I'd also try lead just to see what it did...
Damn, I'd love to play with a laser! BE CAREFUL! Respirator, goggles, please...

Best, Dan

[Terry Gallentine]

I tried Mason Stains because I use them all of the time in screen printing but they didn't work with the laser. They were burned away by the laser and ineffective. I believe the metal oxides and carbonates work because they are actually coloring the glass at the immediate point of contact of the base glass and the oxide coating when the laser hits them.
Thanks for the list of glass colorants Daniel but the laser responds differently to colorants than say a colorant in a glaze that is kiln fired. Some of the oxides (like iron oxide) simply are burned away by the laser. With iron oxide I believe it may be because the iron oxide is a flux besides being a colorant. What I need is a short list of the most potent of the glass colorants that I can try out as a starting point and don't worry I have the laser is in a power ventilated enclosure. I don't even smell the carrier mediums burning out. The laser burn point is so small that it doesn't seem to cause thermal shock to the base glass.

[Barry Kaiser]

I've done a lot of laser etching for dichro and irid removal.
It is very finicky. No problem with the glass breaking, but if you etch too deep, the glass will devitrify. Too light and you don't remove the coating.
You have to learn the balance. Actually different colors of dichro have to be etched at different power levels.

[danieljanse]

Most potent...hmm. Well you certainly started with the best: Cobalt. Doesn't take a lot of chromium to make a green. We use the potassium version because it goes into a melt better than other forms. Copper gives a light blue so it may be too weak for your application. Silver gives a really weak yellow. There's a funny history I read about an amber glass that was misidentified as colored by carbon for a long time. Turned out is was sulfur so that may be somewhat potent. I don't have experience with selenium and cadmium because they are just too nasty for me to deal with. I tried once and it ate right through my color crucible. You're may be a bit of a pioneer here and, while I understand looking for all the info you can, experimentation will be the only true test. A guy with a laser knows that though!

Here is some literature (attached). The book pages are from Glass Notes by Henry Halem and the recipes are in the public domain. I am posting the recipes so you can get an idea of how much colorant is added to a glass batch. Hopefully this will serve as a measure of potency. Another great book source is Coloured Glasses by W.A. Weyl.

[Terry Gallentine]

Thank you Daniel. The batch colorant page is especially interesting. I need to access some small test amounts of some of the metal oxides (or carbonates) and I will probably give sulfur a run. At least I will find out with sulfur how well my vented enclosure works.

[danieljanse]

Pottery supply, US Pigment or LabAlley.com are great sources. Good Luck

[Don Burt]

China/Porcelain overglaze colors i.e. 'china paint' might be a good thing to try. They've figured out the oxide combinations already and sell it to you in a low(er) temperature glassforming powder. And they have reds that are stable and not always full of cadmium. If lasers can sinter china paint and develop the colors well onto your glass you would have a very large gamut of colors to work with.
see http://dbaoriginals.com
and https://warmglass.com/enamels/
There's always a number of us who would rather use the original oxide colorants because it would give our process a romantic sciencey mystique. That panache can be spun into all kinds of artist's statement stuff. But a wide-ranging color palette with consistency can be valuable too.

[Terry Gallentine]

Thanks Don. From what I have been encountering, I get the feeling that glass paints or China paints would vaporize too quickly but I will experiment using some glass paints that I have around.

[danieljanse]

I like Terry's point about the proper ratios already being composed in paints. I just bought Sunshine paint from Brad's website and it comes as a powder that you, the artist, can mix to a paint with flux and a variety of suspensions. Great video by his wife Jody showing how to do it. The Sunshines are lead based and another series called Samba are not. All are from Ferro which has become the conglomerate Vibrantz. Wish I knew where to buy Samba powders as it seems they only available come premixed as Color Line. Anyone know?

Frits are pre-made glaze mixes (not actually glass 'frit') and some have color. If you do a deep search dive on Ferro you will find many many lines of color.

[Terry Gallentine]

I have been working over the years with techniques to permanently put imagery into glass. That involved screen printing either enamels or stains (mixed with low fire frit) onto glass. The problems that I had were that the enamels were too easily broken down by alkalis and acids, as were the mixes of ceramic stains with low fire frits. Because of these problems with enamels and stains, I have been working with laminating images between sheet glass and then casting those into forms. The thinking being that the sheet glass will be more resistant to the alkalis and acids. The problem is that enamels don't hold up to the casting temps and the stain mixes crack up as the glass becomes more fluid. Does anyone out there know of anyone who sells a 96 COE clear that is ground to the same mesh as stains or enamels? I have only encountered clear frit that is powdered and that is not a fine enough mesh for me to mix with colorants and spray into a coating.

[Kevin Midgley]

grinding the frit smaller in a tumbler might be your only option.

[danieljanse]

Kevin may be right. Consider using a blender or coffee grinder with clear glass powder. I can get my raw ingredients down to a powder form that is incredibly fine....like floating in the air, wear a mask fine.

I frequently check the FB marketplace for deals on fusing supplies and tools. A name that always comes up is Peggy Karr. Not sure how her designs resonate in the serious fused art glass community, but her story is pretty remarkable and, of course, they have closed shop. The elaborate stencil approach they took to applying layers of color is pretty remarkable. No doubt those powders would stand up to some seriously high temps. I have no idea where they got their color powders or what it is compatible with. Seems they left a TON of intellectual property and tools "on the table" by closing rather than selling. I imagine somewhere sits a warehouse full of some very cool things to experiment with.

[Barry Kaiser]

Find a listing of Pimco and Ferro Fluxes online. There are literally scores of them with varying activation temps and compositions.
You will find one with the properties that you want.

[Terry Gallentine]

Thanks Barry. Previously when I was mixing stains with low fire frits, I was getting the frit or "flux" from Fusion Ceramics. At that time, I was more interested in the low temp fluxes but now I should look into the higher temp frits that Pimco or Ferro have. One of the reasons that I used Fusion as a supplier was that they could supply me with smaller quantities so I will check them out too. Thanks again.