Fused Glass Trial and Error

"Trial and error" and "test and learn" are used a lot in business and imply that one is optimizing or improving upon a process or product.  I've used these terms in product marketing and research, especially.  However, when they apply to fused glass, it's a different story.

Most people who see my work don't see behind the scenes.  When I venture into a new area, there's always a learning process.  Most of the time, it means failure.  Repeated failure until I get the firing schedule right.  And here, failure means cracked glass and lost time.

Part of the problem in the past has been my kiln, which I corrected by getting a new kiln.  Part of the problem is that the new work I'm doing is more complex, using multiple colors at higher temperatures with longer hold times (which can change the property of the glass).  And, part of the problem is that I'm firing multiple times and working on larger pieces.  My new work with pattern bars is particularly susceptible to breakage, typically along the seam where two bars are joined. Even though I have learned to fire very conservatively that doesn't always guarantee success.

Fortunately, glass can be repurposed so not all is lost.  I try to retain the design elements to use in new work.  Having a tile saw can be a real asset to cut up the glass and use it again.  Here's a picture of a piece that will be used to make a bowl.

Although glass failures are not ideal, there are still some lessons that I can pass on, so hopefully you won't have the same issues.

• Check your kiln elements relative to the size of the piece.  I was having problems in my old kiln as I was pushing the size limit with 12" squares (kiln interior was 14.5") and elements that were circular, making it difficult to heat the corners (notice the crack line in earlier photo above).
• Fix any sagging elements.  My "new" kiln was used and had one sagging element (hanging down about 2" from one end of the kiln to the other) which created uneven heating, especially on large pieces.
• Keep good records of your firing schedules so that you can make adjustments on future firings.  When in doubt, slower is better.  You'll want to make sure to have a long enough annealing hold based on the size and thickness of your glass piece.  And, if you notice that the glass is cracking on the way up, you'll want to increase your annealing and/or ramp up slower to 480-600 degrees.   The more important the piece, the slower I go.
• Don't coldwork the piece until the glass is cool.  This can add to its stress.
• Test your kiln to see how the heat is being distributed. Bullseye Glass has a good tutorial on this here
• Consider making a "test" piece first.  I typically don't do this but recently I've had a problem slumping a piece in my new kiln.  Before I make another attempt on a real project, I am going to make a test blank to make sure I have the right set-up and schedule.  After going through 3 firings and coldworking, I don't want to lose all that work on the last firing.
• Consider varying thicknesses of glass and anneal for the thickest part, especially if you are tack fusing or have varying layers and are not full fusing.  This hasn't been an issue for me as I don't tend to create work that is tack fused but I thought I would pass it along.

Live Jury Experience

In my prior post, I mentioned part of the reason that I was creating new work besides just overall interest in the technique was for a live jury that I had this month.  Normally, jurying just involved submitting photographs but for this jury, each candidate had to select 8-12 pieces that they would set up on a 6' table.  The jurying took place at Fort Mason, San Francisco and all the artists had to be set up by 7:00 pm.  Then we had to clear the room (a waiting area was provided) and come back at 9:30 pm to pick up our work.  Fortunately, I live in Oakland, so it wasn't too difficult to travel back and forth.  However, some artists drove from Chico or Los Angeles and had to spend the night.

Here's what my table looked like:

While, its a little hard to see each item,  this give you an idea of my display and set up - symmetrical, on white, with lights behind the three main pieces, which was a nice effect as I didn't get the benefit of being in front of the window once the sun went down.

Unfortunately though, I was not accepted to be an exhibiting member.  The feedback was that while the judges appreciated the technique, they wanted to see a deeper exploration in terms of form.  I should mention that the jury was made up of ceramicists and glass artists, so for a ceramicist it's much easier to have different forms of bowls, vases...etc.  Their comment was that my shapes looked similar, which was actually my intent.  I make plates and platter in the same shape so that they can be mixed and matched.

However, they encouraged me to apply again (next jury will be in October; although jury members will be different).  So I guess in the meantime, I'll be playing around with some bowls and possibly draping to get a vase-like effect.  If you have any suggestions for other forms, please let me know.  And, when I get around to taking close-up photos to put on my website, I'll include them in a post so you can better see the designs (or include a link to my website).

Making Fused Glass Pattern Bars - Part 1: Prep

I have been fascinated by pattern bars as I love the colors and designs that they make.  However, the "how to's" of pattern bars are not easy to find.  So in 2009, I took a class on how to make them offered by Brock Craig in Vancouver, Canada.  While I had planned to take the class later (closer to the time I actually planned to make them), this was Brock's last class and I wanted to learn the technique, a couple of which he developed.

Here's an example of what Brock calls a "random pattern bar." I've also seen this technique referred to as a "progressive pattern bar," which I find a little more descriptive.  While I made the pattern bar in Brock's class, I finally got around to fusing the bars into a panel and I am very happy with the results.

Making pattern bars require a fair amount of prep work.  The first thing you need are dams for containing the glass.  To calculate the number of dams I would need and their size, I did the following:

• Determined how I would use the pattern bars in finished work - this tells me the height of the dam
• Next I made a plan for how I would lay out the pattern bars on the shelf - this tells me how many dams I needs of each size 
• Then I made a plan of how I would cut up my kiln shelves.  Note: if you don't have a tile saw, you can go to a ceramics supply store and have them cut it for you or you can purchase dams from Bullseye, although this will get a little pricey.

It took me a while to cut up the kiln shelves as my rip guide broke and I needed to order another one from the manufacturer.  Cutting the shelves was like cutting butter - so easy compared to cutting up glass but also pretty messy as the ground ceramic was everywhere. 

 

Once the shelves are cut, the next step is to apply kiln wash to the dams, ideally on both sides.

I just loaded my first firing - 4 pattern bars.  It took A LOT longer than I anticipated.  Although I had already determined that my first round would contain blues and greens, it took me a while to cut the glass and figure out how I wanted to lay everything out - ideally, altering opaque and transparent glass.  I also had a problem with getting all the glass into the area for the pattern bar, so I think my pattern bars will end up thinner than I would like.  The way you're supposed to do it right is to figure out the ideal weight based on the size (which I did) but I couldn't physically get all the glass in the allotted space.  So next time, I will need to cut wider pieces and see if that works.

The glass just went into the kiln and the next post will share how they came out and show the additional bars (multi-colored) that I plan to make over the next couple of days.