Kilncarving with Thinfire

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I’m posting this one as a response to some folks on warmglass asking about kilncarving, so please bear with me. I’ve experimented with the level of detail possible in a kilncarving, and been pretty pleased with the results. At some point I’ll go back and mess with this some more, see what I can do. (And apologies for the crummy photos–I haven’t quite figured out how to photograph the results; they’re a lot more gorgeous in person)

I was looking for a way to construct small cells of glass that I could fill with color to make portraits and such, and hit on the idea of building up layers of Thinfire paper, fusing 6mm clear glass over the top, and then using the resulting depressions almost like cloissone, filling each in with separate shades of glass powder to achieve the look I wanted.

I’d been fortunate enough to acquire a roll of Thinfire at bargain prices during a Bullseye sale (this stuff ain’t cheap, and I use at least a standard sheet in making a portrait), so I had my material. Next step was to prepare the portrait.

I found a face I liked, a Portland street musician I’d snapped a few weeks earlier, and headed for Photoshop. There I diddled with image adjustments until I had a high-contrast, almost posterized contour map of the musician’s face. I could only get there partway electronically, so I needed to draw the actual contour lines on the photo myself.

I resized my portrait to fit the glass and printed it out in black-and-white (color simply distracts in this method, so get rid of it). Then I decided how many levels of Thinfire cutouts I could reasonably make to depict height and depth in the portrait.

The highest points on the face would have the most layers of Thinfire; the lowest wouldn’t have any. I decided to make the highest points on the face with no more than 10 layers, and used that as a guide for drawing contour lines on the rest of the face. (Since then I’ve gone to as many as 20 layers of Thinfire, but it’s a lot of work and uses up a lot of Thinfire)

(I could go into a huge explanation here about choosing contour lines, but instead, here’s a nice little lesson plan about drawing contour maps). I essentially did what computer animators do–made a wireframe of the face–only I did it by hand in 2D with far, far less detail–I was looking for a relatively “stairstep” style.

To make the layers, I placed a sheet of Thinfire over my photo-with-contour-lines on my light table. Having some kind of light under this is mandatory; Thinfire handles very much like fine drawing paper but it’s pretty opaque. In a pinch you could set it against a window in sunlight and ignore your aching neck.

I outlined the pieces with a fine-line Sharpie marker, which makes the above look pretty busy. Each piece was traced out separately, full-sized, since it has to provide support for the layer stacked on top. I started with the bottom layers (in this case the base head, shoulders and neck), laid it on a sheet of parchment paper and traced the next layer on it so I’d know where things went.

I cut out the next layer’s pieces and stuck them in place with a dab of white glue. Then I cut the next layer, and the next layer, and so on. I learned a few things:

  • Get EVERYthing on one layer in place before you start the next layer, or you’ll get lost (and it’s a good idea to finish one layer before you take a break, too).
  • An Xacto knife is about the only thing that really cuts these tiny pieces well. Scissors take too long and tend to mash the edges a bit, so that they don’t lie perfectly flat. There is a tiny swivel-blade Xacto especially for detailed paper cutting and it works well, but wears out quickly and the blades are hard to change.
  • If you do have problems with curling, brush the whole underside of a piece with dilute white glue, set it in place with some wax paper on top and weight it down for about 10 minutes.
  • The black outlines around the pieces will bug the life out of you while you’re working, but they DO burn off in the kiln.
  • You cannot harden Thinfire with fiber paper hardener to make a permanent mold. I tried (above). All it does is make the Sharpie marker lines bleed pink.
  • I had some success putting a translucent cutting mat between the portrait and the Thinfire and cutting directly on the portrait instead of tracing first, THEN cutting. It saved time, but the extra layer made the lines hard to see.
  • In places where I needed more height, I used 1/32 and 1/8 inch fiber paper, topped with Thinfire. Worked well, but I noticed the contours were a bit softer, probably due to the cushioning of the fiber paper.

I’m not going to tell you this is a fast process; it takes awhile to trace, cut, position and paste all these layers. Once you get them done, though, you have a little layered head of Thinfire that’s very sturdy, and can be fired multiple times if you’re very, very careful not to disturb it in the kiln. The sample at the top of the page is about to start its third firing, which turned out to be about the limit.

I set my Thinfire head on a kilnwashed shelf on top of a 1/32 thick fiber paper to give some texture to the background. I topped it with a sheet of 6mm clear glass (Tekta). I chose 6mm because I wanted as much transparency as possible (two 3mm sheets would have a tendency to trap bubbles between layers), didn’t want the dogboning likely with just a 3mm layer at full fuse, and also thought that 6mm would give me a nice holographic effect with the carving coming up from the underside. (it did)

Three Thinfire kilncarvings ready for firing, with 6mm glass sheets over top. And yes, after shooting this pic I realized I hadn’t filled in the cracks between shelves, so I removed this stuff, smoothed over the shelves, added fibre paper and fired.

I beveled the edges of the Tekta slightly with a 100-grit diamond belt, cleaned it and laid the glass on top of 3mm chads (small squares of clear glass). I wanted the glass to sag first in the middle, due to gravity, and push any potential bubbles trapped in the Thinfire layers out the sides.

I added a pretty slow, ranged bubble squeeze from about 1100-1280, held for a half hour at 1240 just to be sure, then took the glass to full fuse higher than I’d normally go, to about 1490F. The glass took the impression absolutely beautifully, capturing every detail. Here are some (bad) photos; I promise to dig a few of these out of storage and see if I can get better pics.

These pics don’t do them justice; I liked them so much I never did get around to filling them in. If you don’t like the hard lines, you can either soften them with more contour layers or do what I was planning to do originally, add glass powders and shading the way you would a paint-by-numbers set.

Anyway, give it a go and see what you think.

2016-05-16T14:16:00+00:00

8 Comments

  1. KaCe Whitacre November 16, 2014 at 4:49 pm - Reply

    I love reading your techniques. I am inspired by all you do… and do so well. I have cut paper in small detail for a long time…50 years. One thing I’d add to people who are new to cutting detail. If there is a lot of fine cutting start in the center and work out rather than going from one side to another, as the sides will help hold the lines so they’re easier to cut. This support can reduce the strain on the thin lines while you cut. I’m inspired. I did think when you mentioned that if the lines are to sharp or harsh one might sandblast the back side to soften them. Do you think that would work?

    • cynthia November 29, 2014 at 2:27 pm - Reply

      Yes, you could certainly try that. Sandblasting would be the fast way to solve that issue–you could probably also just take some wet-dry sandpaper to it, and catch it very selectively. (and thanks for the nice words!)

  2. cynthia November 22, 2008 at 9:13 am - Reply

    Robyn, Bea, those are great ideas. I never really finished playing with this technique, just got excited by other things and moved on. Would love to see someone take it to a logical conclusion… 😉

  3. robyn November 22, 2008 at 8:40 am - Reply

    Very cool. I like this technique and have thought about something quite the same when I see the results of not cleaning off the shelf between firings. I’m a lazy sort.

    I might try sandblasting some of the relief after firing. Thinking it would look cool in front of another solid piece of colored glass that way.

  4. Bea October 7, 2008 at 4:51 pm - Reply

    Tedious procedure but stunning results.
    For years I did landscape painting and your idea suggests to me a re-entry into landscapes, but in glass. Thanks for sharing.

    Beaa

  5. Lori Greene September 28, 2008 at 6:24 pm - Reply

    Those look great!
    this is exactly what I have been thinking about and trying to do! thanks for all the details

  6. cathycarr September 27, 2008 at 10:38 am - Reply

    I’m going to try this out immediately – fabulous!

  7. jenie yolland September 27, 2008 at 5:31 am - Reply

    Wow, I think your work is truly amazing! Speechless!
    j.

Comments welcome! (thanks)

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