Murano Glass Secrets Revealed
Virginia Wilson Toccalino and Tony Toccalino
It was over 500 years ago that the Venetians rediscovered ancient Mesopotamian techniques in the production of murrini, millifiori and filigree glass These techniques were developed and refined by the Serino brothers on the Venetian island of Murano. They held a patent on the process for ten years before others on Murano were allowed to imitate their style. Prior to the 1600s, these techniques were kept a closely guarded secret on the island. Glass wares created in Murano were commonly given to royalty and dignitaries from around the globe. It is because of the mystique of the process and their highly skilled abilities that Venetians are renowned to this day for their glass.
Virginia Wilson Toccalino and Tony Toccalino proudly work within the Venetian tradition, drawing heavily on ancient techniques, while infusing them with a touch of space-age technology. Our Filigree Stardust bells are an excellent example of this and it is our hope that this article will shed light on the intricate, time-consuming process by which they are produced.
The Fundamentals – Clear Crystal and Colour
Given the complexity of the process, it is important to start with the fundamentals, that is, with the medium itself. Clear crystal is created by blending silica sand, soda ash, and lime with other trace minerals and chemicals. The blended sand, or ‘batch’, is then melted in a containment furnace for approximately 12 hours at 2400° F and is kept at 2100 degrees F for as long as the glass studio, or ‘hot shop’, is in production. Clear crystal, while in the furnace, is a material that must remain in a molten state; turning the furnace off at the end of the day is not an option. Given the corrosive effects of the high lime content in the ‘batch’ and the extreme temperatures required to maintain the required molten state, a typical glass melting furnace may need to be replaced after approximately five years of constant running. Replacement costs for equipment, as well as the cost of fuel, electricity, labour and space are the primary factors that contribute to what some people deem to be high prices for finished hand crafted pieces of glass.
Initially, the most striking aspect of our work is the colour embedded within the clear crystal. However, it is colour that presents the most serious problems for glass makers practicing Venetian techniques. For example, we have all seen paperweights with flowers, insects or designs encased in clear crystal. The object beheld is never organic in nature, as it would not survive the ordeal of being encased in 2100° F molten crystal. These objects, no matter how realistic they may seem, are all created by using various combinations of coloured glass alone. Difficulties arise from the clear crystal and various colours expanding and contracting at different rates while working on a piece. A difference in expansion and contraction between colours causes a sheering effect and will result in the piece breaking when cooled or the crystal cracking around the colour, thus relegating the piece in question to the trash heap. This situation is ideally corrected before production begins by testing the compatibility between all colours involved and the molten crystal. Coloured glass itself, is made by adding metals and minerals in various ratios to molten crystal, and is produced in only a few factories worldwide.
Testing compatibility is a time-consuming, trial and error based procedure that involves layering colours and molten crystal and pulling ‘stringers’, or ‘threads’, of glass similar to a bi-metal spring found in home thermostats. If the glass stringer cools straight we know the colours involved are compatible. If, on the other hand, the stringer arks when cooled, we know that one colour is contracting more rapidly than another, thus causing stress that results in sheering or cracking. Compatibility may be marginally off, causing a piece to break after many years. This test is one of several used for testing the coefficient of expansion, or the C.O.E., of crystal and colours and is essential for producing art glass that will stand the test of time.
The Mysterious World of Cane
Now that we have covered the basics, we can begin detailing the long, drawn out processes involved in the production of various forms of Venetian glass cane used in our stardust bells, paperweights and other work, including: common cane, overlaid cane and murrini, as well as complex cane, complex murrini and millifiori.
A piece of coloured glass, approximately the size and shape of a roll of quarters, is picked up on the end of a glass blowing pipe and is coated with a layer of clear crystal. This cylindrical mass of clear crystal and coloured glass is then heated to a malleable consistency. We then attach another pipe to the free end of the cylindrical mass so that it is locked between two pipes, with one artist at each end. Once contact is made, there is no turning back for reheats, we are at that point fully committed and must proceed to pull, moving swiftly in opposite directions to stretch the mass of glass into a long, thin rod. We will continue to make rods of different colours all day in preparation for the next day’s work.
Overlaid Cane and Murrini
This type of cane is made in a very similar manner as common cane, the difference being that we begin with one piece of colour and overlay it with a selection of other colours. Then we encase those colours with molten crystal and heat and pull in the same way. This is where the coefficient of expansion of colours, or C.O.E., becomes critical. If the sheering effect is present, the entire rod, or ‘pull’, will fracture.
When you hold the finished cane vertically in front of your eyes, what you see is one of the lines that are perceptible in a complex cane or finished piece of filigrana glass. While a murrini is a small slice that has been cut off the cane, revealing a cross section of the composite crystal and colour, which, in our case, looks similar to a bulls-eye or dart board.
Complex Cane and Complex Murrini
Following the pulling of overlay cane on day one, we cut and sort it, looking for consistency in diameter and colour density, and then we bag it in sets of up to twenty canes in preparation for work on day three. On the third day we take our packaged sets of overlaid cane, lay them out or stand them up in a mold, bring them up to temperature with a propane torch and pick them up on the outside or inside of a cylinder of clear molten crystal. The coloured rods, as many as 16 or more, are responsible for the spiral effect we see in complex cane. The spiral effect is achieved by heating the rods and crystal to a uniform flexible consistency and securing the resulting cylindrical mass between two metal blowpipes. With an artist at the end of each pipe, they must simultaneously pull and twist the pipes in opposite directions at great speeds. The pull takes place at approximately 1600° F and must be completed within sixty seconds or less because the glass cools quickly and becomes stiff while suspended in the air. If you twist too long or hard, the complex cane strand will cool, snap, hit the floor and shatter, thus bringing an abrupt and traumatic end to several days work. This happens occasionally and is, in a certain respect, necessary in order to determine the limits of what we can do with the glass. Often, the colour being used is responsible for loss of control. Some colours heat up fast and stay flexible longer, while other colours are slow to heat, or stiffen faster. Thus, an attuned sense of touch to resistance of the mass of glass, as well as a great deal of precision, control and knowledge, are required during a pull of complex cane. The failure of a pull, apart from being disappointing, is a big financial loss in terms of time, material and labour and is occasionally hard to avoid.
If complex murrini is the desired product, overlaid rods or components of similar or various colours are shaped and grouped together and the pull is executed without twisting as with overlay and common cane, see diagram (1A) photo of rods grouped.
(1A) Overlaid star murrini rods ready to be pulled into complex murrini or millefiori cane.
This results in a multi-profiled, single cane, which can be sliced in to ¼ inch sections and grouped to create a millefiori piece, such as a paperweight or blown work. See photo of millefiori paper weight set up (1B).
(1B) Multi-rods cut and grouped to exhibit millefiori
Putting it all Together
On the fourth day we cut and package sets of complex murrini and, or, complex cane rods to be used in the production of filigrana and millefiori pieces. With an end product in mind that is awe-inspiring and unique, we look for consistency of twist, colour, style and size of rods. We then introduce into the mixed package of rods previously prepared strips of dichroic glass, which is a shimmering, iridescent glass product developed by NASA for use in the windows of space vehicles. Dichroic glass, which comes in a multitude of patterns and colours, is created by fusing metal oxides three to five millionths of an inch thick onto clear glass; this, in turn, functions to deflect light and repel harmful gamma radiation in space. When we break down the word ‘di-chroic’ we get ‘di’, or ‘two’, and ‘chroic’, meaning ‘chromatic’ or ‘colour’, thus alluding to this medium’s ability to refract multiple colours, as well as change colour when viewed from different angles. With our preparation treatments, this effect is enhanced significantly. Dichroic glass is not cheap, adding to an already costly and time consuming process. However, the bigger issue is trying to assemble a piece successfully. The reflective nature of dichroic glass means that it not only repels light but heat as well, creating a temperature variance that causes great amounts of stress in a given piece. If this stress is not recognized and appropriately dealt with, the piece can quite easily explode on the blow pipe, particularly when in close proximity to the 2300° F flame in the reheating chamber, known in the glass world as ‘the glory hole’. An additional concern is that the reheating flame is also capable of burning the metal molecules off the surface of the glass, in which case the piece loses any value it may otherwise have had. So again, extreme caution, a gentle touch and a refined sensitivity to the inner workings of the medium are necessary in order to successfully pull this off. The positive side to all of the anguish and difficulty involved in this process is that the most beautiful, ancient filigrana style is now being joined, or married, with the most cutting edge, space age glass, pushing the ancient Venetian style into the future.
On day five we take our packages of pre-selected rods and dichroic strips, and, arranging one package at a time, we alternate the dichroic strips between rods and orient them to exhibit a consistent pattern within the piece. The rods and dichroic strips are then heated in the ‘glory hole’ and softened so they can be joined together with a gentle squeeze. Once fused into a panel, and having reached the desired level of malleability, we can roll the panel onto the end of a blow pipe. This creates an open ended cylinder of rods that must be closed by cinching the ends of the rods together and knocking a little ‘button’ off the piece, which we keep for future use. See photo (2A, 2B & 2C)
(2A) Fusing and compressing rods.
(2B) Rolling up the rods
(2C) Joining rods and knocking off the button.
Once the button is off and the cylinder is closed it is capable of holding air, at which point we can commence the blowing and shaping of the body of the bell. After we have achieved the desired shape, we proceed to transfer the body off of the blow pipe by attaching a metal ‘pontil’ iron to the other end of the piece; we then apply stress to the glass neck, where the body and the blow pipe meet, and gently tap the blow pipe, which creates a fracture in the neck and separates the body from the blow pipe. This is a common glass blowing procedure that allows us to work on the opening of the piece. Now that the body of the bell is attached to the ‘pontil’ iron by the handle end, the other end can be flared open and manipulated to give the bell its characteristic shape.
It should be noted that because of the different colours and types of complex cane used, in combination with dichroic glass, each rod moves independently of the next in reaction to the extreme temperature of the ‘glory hole’. Rods consistent in colour and style will react similarly; however, because the rods are staggered, with some slumping or running sooner than others that are more resistant to heat, the end result is a ruffling effect. This is something the glass does on its own and the exact contours of the ruffle are impossible to predict. No mold is used to obtain any shape or ruffle. This makes these bells extremely difficult to duplicate. Temperature, colour, speed of twisting and the energy flowing from the artist through the pipe to the piece make each and every bell truly unique. Once stabilized, the bell will be separated from the ‘pontil’ iron and placed into an electric annealing oven to slowly cool down from approximately 1000° F to room temperature over a 16 to 18 hour period. This lengthy cooling down process allows the glass molecules to align themselves properly and relieves the internal stresses within the piece, giving it stability and durability. This is absolutely necessary, given that coloured glass and clear crystal is fundamentally a liquid, and will continue to move, albeit imperceptibly, over the coarse of time.
Aside from cutting, sorting and packaging common overlay and complex cane, the bulk of the work up to this point requires no less than two artists. From day six on, one artist can effectively manage the task of completing the bells and putting on the final touches. The first step in this second phase is to take complex cane rods and, using a torch, ‘flame-work’ small matching ball clappers on the end of them, one for each bell body. Once completed, each clapper made must also spend at least 16 to 18 hours in the annealer to stabilize.
On the seventh day we rest – so it was written and so it shall be. Although we still have art-glass bells on our minds.
On day eight we concentrate on bell handles, which we make by gathering clear crystal and shaping it into the desired form. Once the shape is achieved, a complementary complex cane rod is taken and fused on the handle and manipulated in a manner pleasing to the artist. Naturally, these pieces must also spend the mandatory 16 to 18 hours in the annealer.
On day nine we commence the grinding and polishing of the bell bodies and the handles. The mating surfaces must be ground perfectly flat. Once leveled and plumbed, so that the handles sit vertically on their corresponding bells, the surfaces are given a final, fine polishing and the handles are assembled.
On the tenth day the handles must be inspected at the contact points and detailed, insuring a clean, neat fusion. Once completed, the bells are turned upside down and secured in a jig so that the clappers can be installed. Separate jigs must be made for each bell and clapper because the rods used at this stage are of different lengths to suit the various depths of the bell bodies, as each piece is completely unique. The clapper is suspended by the ball end in the jig and secured to the body of the bell using a sterling silver cap and chain. In the past, some of our bells were assembled with bridge and clappers made entirely of glass. These bells take a considerable amount of extra work and haven’t been pursued due to the rather grim cost and return factor. At the present time, there are less than ten bells made by us that fit this description, making them extremely rare. Bells of this type may soon go the way of the dodo bird, unless there is a sudden, unexpected surge in demand.
At long last we arrive at day eleven. An overall assessment of the bell is made, with special attention given to the connecting points of the clappers and handles. Once passing our stringent quality control inspection, the piece is signed by the artist and offered up for sale. See photo (3A).
(3A) Filigree Stardust Bell
On The Seventh Day We Rest !
The following is a simple breakdown of this time-consuming, labour intensive process. Taking into consideration that the preparation of dichroic strips takes a day to complete, we will add one day to the breakdown. Excluding the day of rest, this makes it a 12 day process for our Filigree Stardust Bells and 11 days for a typical filigree bell.
Day 1: One artist cutting and preparing dichroic strips.
Day 2: Two artists engaged in all-day production of common and overlaid cane.
Day 3: One artist cutting and sorting overlaid cane rods in sets.
Day 4: Two artists engaged all day in production of complex cane
Day 5: One artist cutting and sorting complex canes, selecting and matching different styles of rods with or without dichroic glass panels.
Day 6: Two artists fusing complex cane rods into panels, one set at a time, which are in turn used in the creation of the filigree bell body.
Day 7: A day of rest. So it was written, so it shall be
Day 8: One artist engaged in making clappers all day,
Day 9 One artist making handles all day
Day 10 and 11: One artist grinding, polishing and mating and leveling handles and assembling them onto the bell body.
Day 12: one artist inspecting and detailing handle connections; making jigs and installing clappers.
Day 13: One artist detailing and checking clapper connections, inspecting and assessing the overall bell, then signing it
If we look at the breakdown of the process, we see that there are 9 days where one artist can perform the required tasks, and 3 days where two artists are required. This adds up to 12 working days for one artist and 3 for the other, for a total of 15 individual work days. During this 11 to 12 day time period (not including our day of rest) we would be working on one day’s worth of bell bodies, approximately 11 to 12 pieces. In the end, three pieces may not make the grade because of structural or stylistic flaws and will have to be discounted at time of sale or trashed. Thus, only if we’re exceptionally lucky do we pull off an average of three quarters of one bell in one day. When you take into consideration the rising cost of space, natural gas, electricity, insurance, equipment and materials in today’s market, as well as the cost of labour or the return some may feel entitled to for their services, one can only come to the conclusion that the artists in question must be passionately committed to their art form. Well, we can certainly say that we love and are committed to this style of glass, while an economist may think that we should just be committed.
We are pleased to say we make our glass from beginning to end. From melting our own
crystal, producing our own complex canes, to decorating and engraving on a traditional
stone wheel, we have no employees. This is not a factory setup, we do it all.
We hope that you, the reader, have come to a better understanding of the filigrana and millifiori techniques that we use in the creation of our work. Both Virginia and Tony welcome your questions either in person or by email. It’s easy to see why this method of glass making eluded the rest of the world for centuries – no one could wrap their head around the lengthy, intricate process involved. Interestingly enough, when the Murano secrets escaped the Venetian lagoon many hundreds of years ago, the techniques began to show up in the making of candy, baked goods, pottery and plasticized clay products such as fimo. In today’s world, there are a select few who continue these past traditions – creating paper weights, orbs, vases, bowls, goblets, plates and bells –each putting their own personal ‘twist’ on an ancient technique that is as timeless as it is beautiful.
Virginia Wilson Toccalino