Ode to Rhubarb Dichroics

Making Shouting Man pop...

>>>Ode to rhubarb glass

Castuary (that period of anxious waiting while your kiln processes your glass castings) was over last night, and I opened the molds to–as usual–a mix of Christmas and nightmare. Well, maybe not nightmare. Probably more like one of those twitchy, uneasy dreams where you step up to the podium to accept your award and things would be perfect if you’d just remembered to put on pants.

In this case, however, the no-pants moment was brief, and I was reasonably thrilled. And Bullseye Rhubarb Pink-Green Shift and Marzipan may be my new favorite colors.

It’s amazing how much the characteristics of a particular glass affect the outcome of a casting, and in this case the choice of glass (NOT just the choice of color, mind you) profoundly affects the piece. The marzipan did this kinda creamy, bread-at-the-point-of-becoming-toast thing that couldn’t have been more perfect for the effect I wanted if I’d made the glass myself.

But it’s the Rhubarb I’m really excited about. I’m trying different colors for ShoutingMan, who’ll eventually be an inclusion in a much larger piece.

I love dichroic colors anyway–dichroic here does NOT mean the sparkly, iridescent coating on glass jewelry but rather a glass that, like alexandrite or some kinds of sapphire, changes color with the type of light, depth, or angle of view. (“Dichroic” because it shows two colors but I’ve been told the more generic term is “pleiochroic”).

Look at this glass in one direction and it’s a fleshy coral. Change light, change thickness, turn it 90 degrees, and it’s sea green. Cast it into a piece with a lot of angles and thicknesses, and all of a sudden you’re controlling shades of color with the same glass.

I love casting with dichroic crystal, where the extra brilliance really kicks up the effect. Hadn’t tried casting with BE “shifters” before, mostly because I tend to cast BE frit, and the translucent/opaque qualities of frit casting pretty much kill the dichroic effect.

This time, though, I used BE billets, and gosh golly gee whiz, I got the effect I was looking for and a bit more. ShoutingMan has a lot of variances in thickness and angled planes, and the Rhubarb played VERY nicely with that. In this shot, he’s just out of the kiln, no real cleanup at all, with a couple of pieces of flashing that need to go (drat).
This guy’s about 9 inches tall, 4 inches deep and maybe 1.75 inches thick at his thickest point, narrowing to perhaps 3mm at the thinnest part of the forehead. (I was also testing whether or not I could glue colored powder to the billet, let it mix as it headed down the reservoir and the “cheek” region of this mold, giving him an even more forceful center. Didn’t really do that, although it’s given me about a page of tests to try for another piece. For the purposes of this essay, though, please ignore any opaque-looking stripes.)

Now, the color VALUE of a transparent glass (how light or dark it is), will change with thickness. Glass artists use that effect all the time. If you want perfectly even color throughout a piece that changes thickness dramatically (as in, say, life casting), you compensate for the value change by making it hollow with walls of the same thickness throughout, or by filling the center with clear glass. Most artists, though, count on the value change to add life and depth, and in fact the “tints,” i.e., really pale shades, greatly expand the range of thicknesses you can play with.

The value change is happening here, obviously, and I purposely designed ShoutingMan and his brothers and sisters to take advantage of it. If you see him head-on he’s actually quite thin–as you move around to the side he fills out, the values shift dramatically, and the detail kicks in.

I’d hoped that using dichroic glass would add a second dimension, and it did. In this piece the glass is not just changing value, it’s also changing HUE (i.e., color) and to some extent saturation. I wish I were better able to photograph this–maybe you can see it in the detail a bit better–where the glass is thinning out and angling off it’s taking on a greenish cast. Where it’s thicker and more perpendicular to the angle of view (as in the cheeks), it’s becoming a dark burnt red.
Can you see it? It’s subtle, but it’s helping to reinforce the idea of this caricature, that ShoutingMan concentrates the force of his energy into a huge, enraged shout. (Damn, I wish I were a better photographer, or at least could figure out how to more effectively photograph glass…)

In any case, the Rhubarb is definitely the way to go.



  1. Cynthia Morgan February 3, 2008 at 12:39 pm - Reply

    Hey, Lynice! Thanks!

    The few times I’ve tried to use found objects in my sculptures they’ve looked so out of place I’ve taken them out. There’s just something too “finished” about them or something. So no, about the only thing I’ve ever put into a piece that I didn’t sculpt myself are leaves (and I modify them quite a bit). It would save a LOT of time to use found objects…but it just doesn’t look right. So now I build all my models in clay.

    I used to do one-offs and take the mold directly from the clay, but the variabilities in the casting process were losing too many pieces (after a LOT of work). Now I usually make a mother mold of my models so I can play around with multiple copies until I get it right.

    Hmmmm. Maybe I’ll post some pictures of ShoutingMan in progress… Thanks!


  2. Cynthia Morgan February 3, 2008 at 12:28 pm - Reply

    Elizabeth what a nice thing to say, and I thank you!

    I don’t generally post pictures of finished “heartwork,” (in part because they drag on so long that I get sick of them), only the quick projects that I don’t put so much into. However…I’m trying to work things so I have more time to work on glass and it doesn’t take 6 months to get to the end of one piece. Hopefully that means that I’ll get ShoutingMan done before long…

    Yeah, Eric’s a sweetie and a wizard in the coldshop–I brought a couple of my sculptures to BE’s pate de verre class to get his advice on coldworking them (and he was spot-on). While we were discussing them he mentioned that he’d love to see what one of them would look like in Rhubarb…

  3. Lynice February 3, 2008 at 11:16 am - Reply

    Hi Cynthia. Shouting Man is beautiful. Did you sculpt the original positive out of clay or is it a “found object”?

  4. Elizabeth February 3, 2008 at 8:21 am - Reply

    I recently attended the casting & coldworking class at Bullseye. Eric our instructor has several pieces just our of the kiln made from rhubarb billets. The effects of this glass is so wonderful it inspired me to purchse a dozen billets in that color.

    Shouting man is magnificent & the rhubarb works with the piece really well. I can’t wait to see the finished product.


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