Glassists testing products would do well to remember this maxim:

Failure is good. Each failure deepens your subject matter expertise.


When it comes to enamels-on-glass, my subject matter expertise must be about as deep as the Mariana trench.

Bullseye Glass kindly included me in their beta trials of a new (for them) product line: Color Line Enamels.
Right about now I’ll bet they’re wishing they hadn’t. 😉

Color Line Enamels are made in the UK, meant to be airbrushed, painted, printed or otherwise applied to glass or ceramic surfaces, then fired. They come in a bunch of luscious colors; Bullseye gave me four very sedate bottles to test but every time I visit the BE Resource Center their wilder siblings call my name and I almost* buy them.

Color Line isn’t cheap, averaging about $20 for a 2.2-ounce bottle. OTOH, if my tests so far are any indication, a bottle lasts quite awhile. You can buy all 18 colors (along with an empty bottle for mixing and a tip set) in a $345 kit, which saves you about a buck a bottle. Price-wise, they’re comparable to Ferro Sunshine enamels, maybe two-thirds the price of Fusemaster.

Before we get into my trials (and TRIALS is the correct term), let me show you what these paints do in the hands of one who understands glass enamels, my friend Valerie Adams. She says that Color Line paints are “promising:”


I am encouraged by this because my own painting test panel was, uhm…less promising:


Please note that this isn’t my usual careful testing; I’m not weighing or doing volumetric sampling when mixing colors. I’m making photographic records and taking some notes, but these first tests are more to get my bearings than any definitive product examination. And since this was the last firing for Skooby the Skutt, more rigorous testing was going to have to wait for the new kiln to arrive anyway. So take this post with a grain of salt. Or three. 😉

ALSO: I absolutely, positively WELCOME any suggestions, criticisms, hints, instructions, “look dummy!s” or other helpful comments you would care to post. I’m not kidding when I say I am a newcomer to glass paints and enamels; I need all the help I can get. So please…help!

colorline1-paletteHow this disas…er, learning experience occurred
I made a test palette by slicing off a 3″ x 5″ piece of the provided 3mm Slate Gray sheet, topping it with a piece of 3mm clear, and firing on top of some ThinFire cutouts created by my Silhouette Cameo (more on that in another post). The resulting fused panel had 32 little cells I could fill with various enamel mixes.

I had four colors (Black, White, Red, Blue), so I focused on seeing how many colors I could make by mixing. Theoretically, I should be able to obtain red+blue=purple, white+black=grey and all sorts of variations on those themes.

I started mixing colors and applying them to the cells. Color Line has a texture about like thickish acrylic paint. It took a fair amount of shaking and squeezing to get it down into the nozzle area of the bottle and flowing out of its bottle.

colorline1-test squigglesBullseye provided little metal nozzle tips that screwed onto the tops of the bottles; I tried applying lines with each tip. With a bit of practice I could write directly with the bottle or the tip; the enamel goo was thick enough that it pretty much stayed right where I put it, without spreading.

I wrote some stuff on a piece of my favorite neutral scrap (Light Peach Cream), then tried dabbing it on with a brush, making some strokes, going over the top of dried lines to see if it would dissolve and spread in the new flow (it did).

I didn’t want to waste my BE-provided glass until I knew how these things were going to react in the kiln, so I switched to plain old clear glass for the rest of the tests. I stuck with making small, pendant-like samples using various techniques.
I took a sgraffito tool and scratched words into dried, painted areas, which looked promising.

I also tried dipping a plastic stamp in the enamel and stamping the glass; the surface of stamp and glass were too hard to apply much ink. I then painted the enamel directly onto the stamp and applied a bit more…but not much more. Clearly, that application method needed soft rubber stamps and I didn’t have any handy.

I tried layering dots and swirls of enamel paint, adding silver foil and thin copper sheet. I did more sgraffito and overlaid that on foil, copper and dichroic glass.

colorline1-saggarboxCompression bar trial
Finally, I tried cutting two roughly 3″ x 5″ sheets each of the BE-provided grey and opaline glasses plus a number of 3mm clear, and painted one side of each piece with black enamel. Then stacked them, enameled side up and alternating grey/clear all the way up the stack, for a total of 20 sheets.

I lined my pattern bar saggar box with fiber paper, laid my stacked sheets inside, and topped them with another fiber paper sheet. I topped that with the saggar lid and weighted it with a kiln brick.

The stack’s tendency to flow out to 6mm would be accelerated by the weighted lid. Each layer would thin as the glass spread, giving me fine lines of grey separated by clear glass.

I wanted to see what the black enamel would do between those layers. Would it act like black powdered frit, and engulf the delicate layers? Or would it politely stay thin and quiet, giving its more demure siblings a chance to shine? If it did, then enamels would become a good way to add dimension to layers in compression bars.


Twenty 3mm sheets is 60mm or nearly 2.5 inches of glass to compress; I’d need enough heat and time to let the glass spread to 3/4 inch (20 mm) or so, and then an appropriate annealing schedule. Would that overfire the enamels, especially the single layers in the flat sheet tests?

The Color Line bottle offers surprisingly little info on using the product (probably they figure you’re already experienced at this stuff), so I headed over to their website for more information.

Color Line simply says to apply, let dry thoroughly before firing, and vent the kiln, especially if you’re using reds. They give a top temp of 1500F but don’t really list a limit on the AMOUNT of heatwork you should (or shouldn’t) give the enamels.

Given my results, I suspect there is a limit. Here’s a gallery of my initial findings:

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Further testing needed to confirm, but here’s what I’m seeing as far as painting and drawing goes:

  • Reds are heat-sensitive when it comes to glasses, glazes and enamels, and Color Line is no exception. The compression-bar firing length pretty much killed the red in almost every test sample.
  • colorline1-blackbleedresultColors spread and bleed when thickly applied. Lines made with Black, Blue and White, but especially Black, grew up to 3X their original width. The black seemed to separate out, giving the appearance of a dark greasy stain. Red may spread too, but it’s kinda hard to tell since I pretty much baked it out of existence. I didn’t much care for it, but suspect people who can actually draw and paint would know how to exploit it.
  • Brush strokes are preserved really, really well…although the bleeding is a problem. Again, if I could draw and paint I’d probably figure out how to use this.
  • There’s a definite heatwork limit on these things. My next tests probably need to stay closer to slumping temperatures than full fuses, or at least to shorter full fuses. That would argue against using these in all but the shortest, thinnest castings, which is kinda disappointing.
  • You mix colors like paint, but again, you probably need to keep the heatwork down to exhibit the full spectrum of color.
  • It’s probably too thick to use straight from the bottle? I thought that the enamel flowing out of the bottle must be the correct thickness so I rarely diluted. Given the way this stuff bled all over the glass when fired, it was obviously ‘way too thick, so applying straight out of the bottle seems to be a no-no.
  • Firing capped works perfectly well. Head-scratcher, that; Color Line says you shouldn’t cap enamels and fire, and I’m not sure why; it seemed to work just fine. Given the sensitivity of reds, wouldn’t multiple firings be a problem? About all that happened when I tried was that etched areas trapped bubbles, but colors actually got better..
  • I can’t paint. We have once again proved that painting and drawing are not my strong suit. Why can’t someone invent sculptable enamels?

Compression bar results
Since the above test results were probably skewed by the need to give adequate heatwork to that stack of 20 enameled sheets inside a fiberpaper-lined saggar, I was very interested in what came out of that saggar.

The outside of the bar was intriguing; the black enamel had acted almost like watercolor and made really beautiful drift patterns across the surface as the glasses blended. Where normally you got clearly defined bands of glass color, the enamel softened those transitions, making them look almost geologic. Yum.

It was almost too pretty to open. Almost.

Any type of pattern bar or murrine cane is kinda like a geode; the only way to know what’s inside is to open it. If you’re patient, you set up your tile saw and start sawing away.

colorline1-compressionchunksProblem was, I’m not patient, I’m in the midst of a studio remodel*** and my tile saw is buried under a bench grinder and assorted boxes. My 5 pound sledgehammer was right on the worktable, though, so one good whaaaack! and that compression bar opened right up.

colorline1-compressionedgeI’ll probably regret that later, but…wow. THIS part of the Color Line trial was not a disaster. I’d alternated one grey opal sheet with a clear, painting one side of each with a thin layer of Black Color Line, remember.

colorline1-compressionfragmentsThere is a LOT going on in this slab. First, you can see how the layers of glass and enamel softened and came down in stages, with each stage looping back on itself.

Second, the black enamel created a sharp demarcation between the layers, but the bleeding effect I noticed earlier in the flat tests works beautifully as the glass moves around. It adds very subtle dimensionality and gradient fills to the layers.

The clear layers appear to absorb the black and become black themselves…until you see them on edge, fully transparent. The Opaline does its usual gorgeous translucence, and the greys–which I’m normally not the fondest of–stay understated, making this more about texture and rhythm than contrast. Or something.

The Mink, that purply-barfy grey sheet that I thought looked too warm for the rest of the greys Bullseye chose for this pack, adds welcome interest (which kinda surprised me; I very nearly left it out).

I’ll count this one a success.

This slab was thinnish and rather uneven, a result of using minimal glass in a single compression firing. I don’t have my usual inch-plus thick, 5×7 inch hunk of sliceable joy.

Typically, I’d use more glass (probably 24 6″ x 6″ sheets), and compress over two firings to achieve layers this thin. That would give me a thicker, more sliceable stack.

But this is definitely a technique worth exploring. Color Line is a lot easier to apply to glass components in a stack than powdered frit, so if I can figure out how to keep the colors from burning out I have an interesting new tool in my casting and murrine arsenal.

The exterior of that slab was equally intriguing, though, and I’d like to see just how far I can control the effects I can get using these enamels and layers of glass in compression. Add in a little judicious coldworking to reveal some of these layers, and I think I could be onto something…


*The only things stopping me from adding glorious Bright Orange, Orange, Yellow, and Aqua to my enamel collection are (a) my incredible fiscal responsibility,** (b) my determination to keep these trials pure and use ONLY the enamel Bullseye provided for these tests, (c) knowledge that I’m not exactly winning prizes with my enamel work to date, and (d) the big Bullseye sale wasn’t until this week.

**stop laughing

***”Well,” she said defensively, “the new kiln can’t come home to a mess, can it?” So the garage is getting visits from handymen and electricians and dumpsters, and the inside studio’s getting a bit of a facelift, too. It’s a mess right now, but it’s gonna be a nice workspace when I’m done. I hope.