Rebuilding the Furnace
Framework, diagrams, and historical considerations
by Jack Schmidt and Jeff Mack
by Jack Schmidt and Jeff Mack
Thoughts about the '62 Furnace
BY JACK SCHMIDT
I worked in the now-famous garage in the late 1960s using an early Labino design furnace. I have had many discussions with people who were at the ’62 workshops. What have come of those discussions are many vague memories of how the first (TMA) glass furnaces were built and many stories about Harvey. The late Tom McGlauchlin was an early student of Harvey’s and in that first workshop.
Apparently Tom was one (perhaps the only) person who built a furnace just like the TMA workshop furnace in Iowa(Cornell) where he was teaching ceramics. Fritz Dreisbach, a painting student, took a glass class from Tom. This was Fritz’s introduction to hot glass.His first inspirations about glass came from seeing cathedral windows in Europe. Here was color coming from within a material not out of a tube and on to a canvas.
Tom McLaughlin, along with Tom Malone and others, spent many hours with Harvey in Madison helping with their new glass program.When I asked Tom McLaughlin about the workshop furnace he responded by handing me a Xerox copy of an image of the furnace.When I asked Norm Schulman the same question his response was that he needed a pencil, paper and time to bring back the memory of the furnace.Unfortunately all he had was the pencil and paper.He did however remember that the unit wasn’t hot enough to melt Harvey’s batch. Clayton Bailey remembers that Harvey and Pat McGlauchlin (Tom’s wife) threw pots, which were used, as crucibles in the first furnace. When Nick Labino came to see what was going on he suggestedremoving the crucibles and to fill the furnace with Johns Manville 475 marbles, which were being used to produce fiberglass in the nearby Waterville, Ohio, JM factory.Nick was VP in charge of research at the JM plant at the time.Before filling the furnace with marbles, Clayton remembers that they lined the interior with hard firebrick, which would withstand melted glass.This liner went over the interior insulating brick.
He and Tom then went to Waterville and came back with the 475 marbles, dumped them into the furnace and waited.In fact. they were to spend the night with the furnace since the TMA would not allow it to be unattended through the night.The first two days of the workshop the furnace had to be turned off at the end of the day.The marbles melted fast so Tom and Clayton took advantage of the situation and proceeded to blow late that evening and into the early morning hours pretty much emptying the furnace.They recharged with the marbles and the glass was ready in time for the others to blow by the start of that day, Wednesday.
At this point what we know is that the original furnace was built much like a small ceramic kiln meant to hold crucibles.It did not have a liner meant for glass contact.And the liner added during the March workshop was only hard firebrick.Although this brick is durable enough to contain hot glass, unlike an insulating brick, it is high in iron and not as durable as a high alumina crystallite brick.One could expect a short life and considerable iron green to leach into the glass from these hard firebricks.
The later, Labino design used the crystallites as a glass liner, which became the standard for many of the early furnaces and Harvey began using them after the Toledo workshops.Some furnaces utilized a flat hard firebrick large enough to span the top of small furnace instead of the arch brick used in furnace number one.This type of roof made it easy to utilize a Labino burner block carved from two 3000-degree insulating bricks.
By the late 1960s, artists like Mark Peiser were experimenting with crowns made of castable refractories like AP Green Mozzou.This allowed for a smooth one- or two-piece crown with a port for a burner.Unlike furnace #1, the Labino design units were fired from the top.Furnace #1 was a side-fired unit with a commercial burner block.This burner block did not accommodate any safety devices.The burner is not evident in the early images but, from what is visible, it appears to be similar to the early burner on a Madison side-fired furnace.Johnson Burner Company sells a similar unit today.The fuel is mixed with air just in front of a small blower.
At the furnace end of the burner and just outside of the burner block is a flame-retention nozzle. Its also possible furnace number one had a burner similar to an Alfred burner.Remember all these guys and one lady were potters.It’s a system commonly used on a ceramic kiln.Unlike the Labino burner, the tip is not embedded in a burner block but positioned just outside a burner block opening at the side of the furnace. A venturi burner would depend on secondary air and high-pressure natural gas or propane but not a blower.Labino’s furnaces in Grand Rapids ran on high-pressure gas.Many of the early furnaces at the craft schools like Penland and Pilchuck ran on propane with venturi burners.These were soon replaced with specially designed burner tips and blowers to increase efficiency.The furnaces designed by Fritz Dreisbach in 1969 for the Toledo Museum’s new Glass Crafts Building incorporated some of the first redundant safety systems to be used on small studio furnaces.The burners on these furnaces included an ignition system and a port with a flame sensing devise called a purple peeper.High and low pressure sensors on the gas line, blower pressure sensors and magnetic switches for electrical power failure were all included in this design.
Studio furnace design has come a long way. Units used today in schools across the country bear a closer resemblance to those used in large glass factories except that ours are small.It’s also interesting to note that Harvey’s design for furnace #1 is more commonly used today than the Labino furnace.And that is a firebox with a large crucible in it.I think it’s also worth noting that early on artist tended to work alone in the studio contrary to the factory system. Today most artists have one or more assistants on hand before they pick up a pipe.Things have truly come full circle.
_The “’62 Retro Furnace” Design for the 2012 Minkoff Residency at the Toledo Museum of Art
BY JEFF MACK
One of the objectives for Jack and my participation was to develop a design for a furnace that would exist as a component for the Toledo Workshop Revisted Residency at the TMA. The idea is to reflect on the spirit of the early studio glass movement by requiring the residents to build a furnace to work with, and do that on the same basic schedule as the group in the original Toledo glass workshop in 1962.
Today, we take the glass furnace and studio for granted. Now you can walk into a studio with only a bag of your favorite glass tools and start making glass. In the early days of studio glass you needed a few more things because, if you wanted to make glass, the first matter of business was usually to build a furnace. This was typically done in a day.
Incorporating this process into a modern residency pays homage to the pioneering spirit of the early studio glass movement. At the same time it creates an interesting juxtaposition, since it will be built and operated in the shadow of one of the TMA’s new state of the art Wet Dog furnaces that came shrink-wrapped on a palate with no assembly required. It is a quite literal illustration of how far the studio movement has come with furnace technology in the past 50 years. We have really come a long way and the growth development and specializations that have evolved are a testament to that in the studio glass movement.
For the furnace component of the residency, the idea developed and a design was necessary so that we had the appropriate materials on hand for the residents.The design was to follow as closely as possible to the original studio glass furnace that was made here for the workshop in 1962. Unfortunately, there is no known drawing of the first furnace, so some research was needed to come up with a clear picture.
The drawings for the residency furnace that emerged are based on information gathered from Jack Schmidt’s personal interviews with participants and those who worked closely with Harvey Littleton. We also utilized information, drawings, images shared by Jutta Page, Curator of Glass and Julie Mc Master chief archivist at the Toledo Museum of Art. In addition there were also contributions of images, information and insights from Harvey’s son, glass artist John Littleton.
For the design we felt that it would be important for the furnace to look similar to the original, that way it can stand as a working monument to the birth of studio glass. We used available images to give us clues, and sort of worked from the outside in.As Jack states, the original furnace was intended to hold crucibles, and therefore didn’t have a proper liner. That has been modified in this design, by suggesting that certain bricks be some type of liner. Perhaps the residents could use some of Jack's own old crystallites that Fritz left with him 40 years back. This would be really appropriate as they caught on quickly and were the benchmark liner material for most early studio glass pioneers into the 1970s. Most early furnaces were built around a crystallite liner.
Because Harvey and these first participants would have been familiar with ceramic kiln architecture, it made sense that the furnace was a sprung arch construction with firebrick interior, backed with insulating firebrick. The interior brick configuration and arch was not apparent from photographs, as it was covered by insulating brick, however a drawing of a later furnace labeled ’63 Madison Furnace acquired by Jutta Page from the Rakkow Library, gave some indication of how the original arch may have been configured. This drawing includes a materials list and suggests for the furnace roof a combination of bricks from two arch configurations designed to span an 18-inch chamber.
These dimensions were concurrent with exterior brick arrangement taken from photographs taken at the ‘62 workshop, so that is what we went with in our contemporary design. We went with simplicity. After all, the furnace was put together quickly so to get on with the glass and art making. The construction is completely from standard 9” x 4.5” x2.5” refractory brick. It is designed to have minimal cutting and to go together quickly.
The placement of the furnace opening, burner block, as well as the type of burner, and door system is clear only from photographs taken at the ‘62 Toledo workshop. It is fortunate that these images remain, because it seems that the original furnace wasn’t really documented in any other practical way. Immediately from its inception, the furnace design began evolving. The very first adaptation was to accommodate melting the 475 marbles.
Over the years, the studio glass furnace has evolved and been adapted in so many ways, but at its core, the small furnace remains a tool of the artist. Which is exactly what Harvey Littleton intended it to be.