Sunday, January 15, 2023

Stained Glass Panels, Part 4

This is part 4 of a series about my designs for stained glass window panels.

Part 1: The eclipse panel

Part 2: The book data panel

Part 3: The hummingbird feathers panel

Part 4: The dichro panel (this post)

In parts 1-3 of this series, I described stained glass panels I designed for transom windows above doors. My fourth panel was for a window on a wall above a stairwell. It was nearly five times as big as the transoms: roughly two-and-a-half by five feet.

My goals were clear from the get-go. I wanted a design that looked like a metal screen and that was essentially opaque. The view through the window (which included a chunk of roof) would detract from the panel, so I wanted to hide it. I quickly came up with this:

I experimented with a lot of color options:

I should have saved myself the trouble. Panel makers told me that the inner right angles on the pieces of glass around the squares would be weak and crack or break. They had to go.

I returned to the drawing board and emerged with a number of designs that had no inner right angles:

Panel makers clarified that any concave angle ending in a point (as opposed to ending in a curve) would suffer the same weakness, so designs 6-8 were out. The simple act of rounding the corners of the squares (design 5) would solve the problem, but I didn't like the way it looked. Rotating the squares 45 degrees (design 1) would also solve the problem, but that didn't look like the screen I had in mind. Nor did designs 2-4.

It occurred to me that an alternative to rotating all the squares 45 degrees was to rotate the connecting lines 45 degrees instead. That was equally effective in eliminating the inner right angles, and it yielded this design, which is the one I ended up using.

Meanwhile, I'd decided I wanted to use dichroic ("dichro") glass for the squares. Dichro glass is magical stuff. It changes color depending on the angle from which it's viewed. Its appearance also depends on whether you're seeing transmitted light (e.g., during the day) or reflected light (e.g., from inside lights at night). Dichro elements in the panel would change colors as you walked by or went up and down the stairs, would look different night and day, and would present difference faces inside and outside the house. I couldn't resist.

I ordered some dichro samples, taped them to a window, and took photos of them from different angles to see what they'd do. These photos show five samples from different viewpoints:

I settled on Kokomo's 33G-MA (second from left in the shots above), and mocked up my design using the photos I'd taken. My goal was to approximate the panel's appearance, at least during daytime. Here are the mockups:

The actual panel puts the mockups to shame:

The three pictures on the left were taken during the day. They show the dichro with transmitted light. The rightmost picture was taken at night. It shows reflected light. In the two middle pictures, different squares show different colors. That's probably because the viewing angle varies from the top of the panel to the bottom, but a contributing factor could be variations in the dichroic coating on individual pieces of glass.

Walking down the stairs provides a steady change in viewing angle that brings the panel alive:

I really like this panel. During the day, the hot-magenta dichro squares glow with color from the most common vantage points, and they segue to a nice peach when viewed from wider angles. As you walk by, they put on a chromatic show. 

I'm pleased that I heeded the lesson from panel 3 and made this panel opaque. The dichro squares against the wispy white background pop, just as I'd hoped, and there's no distracting view of sky, clouds, trees, or roof peeking through. 

There's a price for that. The panel blocks most of the light coming through the window, and the stairwell is now dimmer than my wife and I would prefer. I knew that putting a panel in front of the window would darken things a bit, but the effect is more pronounced than I had expected. My experience with the transom window panels led me to believe that putting a panel over a window wouldn't have much of an impact on the light in the room, but in retrospect, that was because each of the transoms was over a door with a much larger window in it. The larger windows provided enough illumination that reducing the light through the transoms didn't matter. In the case of the stairwell, the panel covers the only window. The darkening effect is considerable. 

The takeaway from panel 3 was that what's outside the window should affect the design of the panel. The takeaway from panel 4 is that what's inside the window should affect it, too.



Harlan Crystal said...

After reading the snippet "inner right angle" I found myself googling to understand how this is different from just a "right angle." The design you went with has some squares -- I still don't understand the distinction between the right angles here and the ones in the original design which were structurally weaker.

Scott Meyers said...

The "inner" right angles in the original design are the concave ones in the corners abutting the squares. The final design has right angles, but none are concave. Convex angles (right and otherwise) are not problematic.

If you look at lots of stained glass designs, you'll notice that most of them avoid concave angles meeting at a point. Instead, they use convex angles or they use curves. I have seen a few designs employing convex angles meeting at a point, so it can clearly be done, but my sense is that cutting glass pieces into shapes with such angles requires special equipment (e.g., lasers or waterjets), and the resulting panels may still be susceptible to cracks developing at the points where the lines of the concave angles meet.