To start off the first Bullseye class of my week in Portland, where we were learning about screen printing onto glass, we started out our first project with some practice printing onto paper and then glass. Each of us had our own large work area and we had five screen printing stations to share among the seven students. With the good ratio of equipment to students, there was never much waiting time, since each person took a different amount of time for the preparation before actually being ready to use the screens. By the time the first people were done printing, the last few were finally ready for the printing stations. For our first project, the screens had already been prepared in advance by our instructor, Louise Krampien.
We started out with an introduction to the class, and some basic instructions as we looked over the samples Louise had provided (our project samples for practice printing are shown in the photo [I apologize for the blurry shot] above and to the left) for each of the projects we were going to be doing. Next, she showed us how to mix up the glass enamel we would use for the screen printing process and did a demonstration of how to properly use the screen printing equipment. Then, we were able to mix up our own batch of black enamel “ink” and go for it at a screen printing station.
First, we started with sheets of newsprint. This allowed us to check our technique to see whether we were able to print from edge to edge and from top to bottom with firm, even pressure to get a good print. I haven’t done any screen printing since I was in Girl Scouts in high school, so I was really rusty on the process. Stacy Smith’s “Crash Course in Powder Printing,” which I took last summer, really doesn’t count. Although we were screen printing in that class too, printing with powder is a much more forgiving process, as you are doing anywhere between 6 and 12 passes with dry powdered glass versus printing just one pass with a wet medium that you really can’t go over a second time.
It took quite a while to perfect my technique enough get a good print on the paper before I could finally graduate to printing on the glass. Eventually, I did get there, although I did have to wipe off the enamel, clean the glass, and try again when the first print didn’t turn out very well. The second try turned out about as perfect as it could be, though. Yippee!
We each were given an 8″ square of white glass to practice printing on. The black on white gives a very clear indication of any imperfections in the screen printing process. Once we completed the practice printing on the glass, we put our sheet of glass into one of the kilns to fire overnight. This first firing allows for the enamels that we used in the screen printing process to fuse onto the glass sheet in a process called “sintering.”
This first sinter firing is needed for two reasons. The first reason is that the medium we used for the practice printing was a very oily medium that doesn’t dry. Well, I suppose that if you were willing to wait weeks or months, it would eventually dry, but that would take way too long for most of us impatient mortals. The other reason is that if you wanted to use the printed image in any way, like turning it into the plate shown above on the right, even if you could drop the capping glass perfectly onto the print so that it didn’t smear, when the oily medium fires in the kiln it releases gasses that get trapped between the layers and distort the print. Louise had some samples where she had tried firing the enamel between two pieces of glass and the image is quite noticeably distorted.
So, the first evening after creating the print, we did the sinter firing to properly fuse the enamels onto the sheet of glass. The next morning, before we moved on to our new projects for the day, we cleaned our sintered piece, capped it with clear glass and put it back into the kiln for a second, full fuse firing. This process heats the glass up enough for the two sheets of glass to fuse together completely into a new sheet. The third morning of class, we again cleaned off the glass sheet, and then placed it onto a mold so that it would take on the final plate shape that you see above and to the right.
While it takes a lot of kiln time to complete the final project, the actual creation time is pretty short. Once I had finished practice printing on paper, it only took another couple of minutes to create the good print on the glass. Clean up and placing the clear glass the next morning took another 5 minutes, tops. Clean up and placing the glass onto the mold on the third day took even less than that. So, if I wanted to create a set of 8 screen printed dishes, it would probably take no more than an hour or so of my time all told – not counting the kiln time. Which makes it a great technique to know if you want to create a large amount of work, say for a show, in a small amount of time.
Also, if you are trying to create a set of something where you are using the same image, or set of images, over and over, it would be a great way to make repetitive work in a short amount of time while keeping each piece looking exactly the same. You could also use the same screen image printed in different colors as another way to create a set of something with this process. Worth exploring…
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