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A History of Flat Glass Washing
Written by: Bob Lang, Solution Specialist at Billco Manufacturing
Flat Glass Washing Equipment is defined in this discussion as meaning a horizontal roller, conveyor-type machine, with several pairs of top and bottom cylinder-type brushes mounted between the rollers. These machines include a drying section consisting of round or rectangular tubes, also mounted between the conveyor rolls, which obtain air from a centrifugal blower. Vertical washing machines will also be discussed later.
The Beginning Years and Suppliers
Starting in the mid-1930’s, the flat glass industry began to offer new products that were more sophisticated than ordinary window glass, as well as began to automate the processes of some existing products. I am speaking mainly of the invention of laminated glass, and the automation of the mirror silvering process. Although insulating glass was invented in the 1930’s, it did not gain much use until the 1950’s.
Some of the companies producing mirrors built their own machinery. However, there were two companies in the 30’s and 40’s building mirror production lines (also referred to as silvering lines). They were Henry G. Lange Co., and Sommer and Maca, both of Chicago. A glass cleaning machine was part of these mirror lines, and should probably be considered as the first commercially produced glass cleaning machines. The glass cleaning machines used in mirror lines were quite extensive, consisting of three cleaning sections:
- Multiple banks of felt pads that rotated and oscillated, using rouge as the medium, were used for actually polishing the glass surface.
- Multiple banks of cup-type brushes that oscillated and rotated, using cerium or detergent as the medium, were responsible for removing the rouge and other debris.
- And finally, several cylinder brushes using water as the medium for final cleaning.
In the 1940’s, the above mentioned companies appear to be the only companies building glass washing machines commercially. PPG, and at least one British company, were making laminated auto glass in the 1930’s. It is suspected there were building their own glass cleaning machines to meet their needs during that period, or they were hand cleaning the glass.
By the early 1950’s two more companies began building glass washing machines. They were Century Engineering, and Billco Manufacturing. Century built mirror lines, as well as machines for cleaning other flat sheet products.
Billco’s Beginnings in the Glass Washing Machinery Business:
Billco records from the early 1950s show that they were building glass washing machines in widths from 14” to 48”, for cleaning glass for tempering, as well as for cleaning small parts for gauge faces, clocks, laboratory slides, and appliance glass panels. A 14” wide washer for cleaning slides and other small parts is shown below.
Interestingly, in 1955 Billco sold a 48” wide washer to Hordis Bros. Co. for cleaning glass prior to tempering. At that time, there were horizontal-continuous, and vertical-type tempering furnaces. This washer for Hordis (an example is shown in Exhibit C below), was for cleaning glass prior to a horizontal tempering furnace, and appears to be the first one that we built for that purpose.
Insulated Glass Unit Manufacturing Becomes a Factor
Early tempering furnaces were problematic for glass washing machines, because the glass was not always flat. I will always remember an interesting revelation from my first, solo field installation of an 84” glass washing machine. This machine was to be installed prior to a production line for manufacturing insulating glass units. The tempered patio doors that the company brought to me for cleaning from their brand new in-house tempering line, had bows of 1” or more. Being a novice, I just assumed that somehow I had to make our washer clean that glass. After several hours of frustration, and a call back to Billco, I had to delicately explain to the company managers that neither our machine, nor anyone else’s, could pass their bowed glass through a flat glass washer. It was quite a learning experience for a young guy just entering the glass industry… and probably likewise for the operators of the tempering line.
By the mid-to-late 1950’s, Billco was beginning to build significant numbers of glass cleaning machines for producers of insulating glass units. These machines were 60”, 72”, and 84” wide, and mainly with 4 pairs of brushes and two pairs of air knives. The reason for the 84” wide machines was primarily so that 34” x 76” patio doors could be processed in the wide dimension, making it easier for two people to handle the door panels as they exited the washer and entered the clean room. A typical 84” glass washing machine from that era is shown.
De-mineralized Rinse Water
In 1958 Billco got its first exposure to what 30 years later would become a very important requirement for glass washing machines, the use of treated, mineral-free water (De-ionized or Reverse Osmosis). During an installation of an 84” wide glass washing machine for cleaning glass prior to producing insulating glass in a mid-Ohio window manufacturing company, we found that we could not eliminate a white, chalky residue on the glass as the glass exited the washer. After discussions with water experts, we learned that the residue was of a very high content of calcium and magnesium minerals in the water, which had evaporated on the glass during the drying process. Only after installing Deionization tanks from Culligan, to supply mineral-free water to the final rinse, were we able to eliminate the residue. This requirement became a life-saver for companies who were using glass washing machines in a roughly defined belt across the United States, from Boston to Phoenix, where ground water generally has a high content of calcium and magnesium.
Successes and Advancements during the 1960’s and 70’s:
In the 1960’s and 1970’s, many hundreds of glass washing machines were built and sold for cleaning glass prior to tempering, insulating, and laminating. In the 70’s, Billco was concerned that the flood of business would surely slow down, but it did not. Manufacturers began installing their own insulating glass unit manufacturing lines in order to gain better quality control over their products. This same phenomenon happened with washers for tempering operations in the 1980’s and 90’s.
Throughout the 1960s and 1970s, the primary washing goal to produce glass that was visibly clean, with no water on the edges. Some washer manufacturers were better at producing dry glass than others, mainly because of the design of their drying systems. Those that were successful were able to use room temperature rinse water, while others had to use heated rinse water. The heated rinse water was much more expensive and also caused spotting problems due to the evaporation of the water, resulting with mineral residue on the glass.
Maintenance saving features were also stressed. All early washers had to be partially disassembled in order to reach any broken glass inside the machine, or inspect and/or replace rollers or brushes. In early 1960, Billco introduced a patented feature in their washers, called a “Flip-Top” (shown below with the top in the up position). This feature allowed access to the internal parts of the machine in a few minutes, and proved to be enormously successful for Billco’s glass washer sales.
Depending upon the quantity of these beads on the glass, some manufacturers required a pre-spray section to be added to the front of a glass washer. This section was primarily responsible for ridding the glass of packaging material in order to prevent contamination of the downstream sections of the washer. Eventually, the pre-spray section became a requirement in almost all glass washing machines. You can see a pre-spray section mounted at the front of the machine shown in Exhibit E).Glass packaging techniques also influenced glass washing machine designs. For the first few decades, glass was mainly interleaved with sawdust and/or paper in shipping cases. One problem with paper was that if the shipping case was exposed to moisture or radical variances in temperature, chemicals could leach out of the paper and stain the glass. Many times these stains could not be removed from the glass surface in a glass washing machine. Glass producers developed two significant changes in their packaging technology that eliminated these problems. First, they eliminated the paper and sawdust, in favor of plastic (Lucite) beads. Next, they began spraying slightly acidic chemicals on the glass that deterred staining.
Vacuum Coating on Glass Changes Glass Cleaning Technology
The years 1973-74 were a watershed moment in glass washer technology. This was the time period that the company Airco Solar Products (a division of Airco-Temescal), introduced their large area magnetron sputtering deposition coating lines, for applying soft coat, low-e coatings on glass. This changed glass washer requirements from that time forward. [Read more…]