So, how it is done??
As some of you know, Sandy and I took a six week driving trip on the “mainland” as we call the “lower forty-eight” here in Hawaii. On this trip a key stop for us as we drove up the Pacific coast was Portland, Oregon. Our interest in stopping there was not only the great food in Portland, but to also visit the Bullseye Glass Factory. This is where the glass we buy for our art is manufactured. The Hawaii rep for Bullseye is Sarah Givens. She was kind enough to spend a couple of hours giving us a personal tour of the factory. In this blog piece I will share with you some of the interesting things we got to see. The photos in this piece are actually taken from the Bullseye catalog. Due to the proprietary nature of Bullseye’s processes, we were not permitted to take photos inside their factory.
The glass we buy comes in eighth inch thick sheets (20×35), in colors we want, and either transparent and/or opaque as we need. We typically order 60 sheets of glass at a time once or twice a year along with other glass related items (tools, molds, ground glass called Frit,…). The glass order arrives some three weeks later, the sheets in a wooden crate which is bundled with the other items on a pallet. The glass order weighs 700 to 1000 pounds and is transported by freighter to Hawaii. It is quite exciting when the order arrives! This trip was an opportunity to see the Bullseye process.
The founders of Bullseye were chemical engineers that were also glass artists back in the late 70’s. At that time, the ability of glass artists to successfully fuse glass of various colors was very limited. For various pieces of glass to fuse properly requires that the “coefficient of expansion” (CoE) of the glass used be very close to the same… otherwise the finished glass piece would fracture. It was very difficult to get glass of different colors to have the same coefficient of expansion. So, these engineer-artists used their engineering expertise to start developing processes to achieve glass of different colors that are fusable. What started off as a semi-hobby quickly became a successful business. In expanding their new business for quantity production, the founders, being ecologically mindful (and probably short on funding), built most of their production equipment out of recycled and scrap parts. What started off as a garage business, the Bullseye factory now covers a city block in Portland.
Now for the tour…at the beginning of the tour, Sarah brought us to the chemical crib where jars of chemical compounds are stored (like “Copper Sulfate”…the only one I remember because I had to analyze it in my Inorganic Chemistry class way… way back),… chemicals that are used to create the colors in the glass. (It reminded me so much of those locked cabinets in my high school and college Chemistry labs.) We then saw steel drums with silica sand and the chemical recipe to achieve the desired glass color and CoE being tumbled…a process that would take many hours to achieve a uniform mixture.
From that factory area, we went to the area where the glass sheets are formed. That involves a team of 5 to transition glass from a liquid state to a trimmed and quality inspected sheet. At the front end is where the exciting and intense activity happens. Three of the team members work that end. One member scoops a sizable ladle of liquefied glass from the tub of glass in the “glory hole” furnace. This glass is white hot at around 2000 degrees F. (The first photos show the furnace and the team member literally running with the ladle of glass to the next station.) The ladle of molten glass is rushed over to a steel table where the second team member manipulates it with steel rods and feeds it into roller machine that squeezes it to one eighth inch thickness and about 20 inches wide. The glass is rapidly cooling and is red hot at around 1300 degrees as it passes through the rollers. The third team member then takes the sheet that is around 1100 to 1200 degrees (and therefore malleable) and quickly moves it to a conveyer belt. (The lower two photos shows the sheet coming out of the roller and about to be picked up to be placed on the conveyer. Since the glass is very malleable and cooling rapidly at this point, it needs to be moved quickly and carefully so the sheet isn’t ruined.) Because of the intensity of this front end work, the three team members swap positions every 20 minutes. I assume they get a break as well.
The conveyer moves the glass sheet slowly through the annealing oven that is hundreds of feet long where the temperature is controlled to cool the sheet down from 1100 degrees to 900, and stay there for sufficient time to equalize thermal stresses, and then cool down to room temperature. I don’t know for sure how long it takes because I didn’t ask, but I think it takes 2 to 3 hours for the glass sheet to make it through the conveyer annealing oven.
At the exit end, the fourth team member takes the fully cooled down and annealed sheet to his cutting table and trims it to 35 inches in length. He tags each sheet with a unique number. The edges that he trims are collected and later ground into Frit. He also does some initial quality assurance steps before putting the sheet on a cart. When some 30 or 40 sheets have been loaded on the cart, they are taken to the fifth team member who carefully inspects each sheet to assess whether it is satisfactory to be added to the inventory for that color run.
There are other quality control steps that occur during a run. Tests are done periodically during the run to confirm color integrity as well as to whether that ever-so-critical “coefficient of expansion” is within some tight tolerance. If it should deviate too far from spec, they would know from the tagging system as to what glass ought to be removed from inventory and what corrective action to take.
So, that’s how they do it. The whole process was fascinating to see up close and in person. We were very impressed with the Quality Assurance process they have in place. We have been extremely happy with the quality of the Bullseye glass we’ve purchased to create our functional glass art, and recommend it to other glass artists.
We did see many other things on our tour…way too many to write about. In any case, we wish again to acknowledge Sarah Givens and give her a big “Mahalo” for spending all that time with us.
Mahalo and Aloha