Savitrine Glassworks

Functional, Unique, Handmade Fused Art Glass by David Dawes. Studios in Bronte and Braidwood, NSW.

Frequently Asked Questions

Payment, Postage & Shipping

All prices include 10% GST
We accept payment using PayPal, Visa and Mastercard (please call to process) or by EFT (Australia only - email or call for my account details).
Please request postage amount at PayPal checkout or by contacting David as shipping costs will vary on weight of piece and your location.
As guidance only a 23 centimetre square plate would cost A$20.00 to ship to Melbourne.
We are happy to ship overseas but shipping costs will be higher.

Why can't you tell me how much postage will cost at checkout?
Simply because we don't know where you live and how much the item or items weigh! We use Australia Post for all shipments.
We package all our items carefully including all or some of bubble wrap, newspaper, tissue, corrugated card, inflatable bags and loosefill ‘peanuts'. We use Australia Post, Officeworks or recycled boxes and may need to charge cost (no mark up) if we need to buy a ‘new' box. We don't charge for the packaging materials used to protect the piece.
What happens if the item breaks during shipment?
Boxes are marked ‘Fragile' but accidents do happen. We insure all shipments and will work with you to get your money refunded.


If you see something you like that has sold, something that you would prefer in different colours or if you have something in mind that you want made as a one off commission piece then please contact David.

 

Glass Fusing - what is it?

What is fusion?
fu·sion  (fyzhn) n.
1. The act or procedure of liquefying or melting by the application of heat.
2. The liquid or melted state induced by heat.
3. a. The merging of different elements into a union: the fusion of copper and zinc to form brass; the difficult fusion of conflicting political factions.
3. b. A union resulting from fusing: A fusion of religion and politics emerged.
4. Physics A nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy.
5. Music that blends jazz elements and the heavy repetitive rhythms of rock. Also called jazz-fusion, jazz-rock.
6. A style of cooking that combines ingredients and techniques from very different cultures or countries.
[Latin fsi, fsin-, from fsus, past participle of fundere, to melt ; see gheu- in Indo-European roots.]
What is warm (fused) glass?
Fused glass is a term used to describe glass that has been fired (heat-processed) in a kiln at a range of high temperatures from 593 °C to 816 °C. There are 3 main distinctions for temperature application and the resulting effect on the glass.
Firing in the lower ranges of these temperatures 593–677 °C (1099–1251 °F) is called slumping, firing in the middle ranges of these temperatures 677–732 °C is considered "tack fusing" and firing the glass at the higher spectrum of this range 732–816 °C is a "full fuse".
All of these techniques can be applied to one glass work in separate firings to add depth, relief and shape.
What is “hot” glass?  
Hot working is the method used to manipulate and form hot molten glass with tools, paddles, blowpipes and punties (rods to hold, move, and spin the hot glass shape or vessel while it is being worked and reheated).  Hot working techniques include: blowing, wrapping of the molten glass around clay or metal objects, draping, pulling and free manipulation outside of the kiln or furnace.  The molten glass can also be manipulated within the fusing kiln by opening the kiln and grabbing, pushing, and lifting the hot glass with tools.  Kevlar gloves, hoods, and face shields are used to provide shielding from the intense heat from the furnace.
What is “cold” working?
Cold working is the work done to the glass in ambient room temperature.  Grinding, sandblasting, and polishing are the more common cold working processes.  When glass is ground or polished, excessive heat is generated due to friction.  Friction from grinding the surface of the glass can generate enough heat to crack the glass, so the glass is kept cool with running water.

So, what do fusing, slumping and casting mean?
There are three main processes, with variations within them. The broad process depends on the temperature, the variation within it depends on the time and also on slight variations of temperature. These processes are:
Fusing: The glass retains its shape, but becomes sticky and adjacent glass pieces join together.
Slumping: The glass deforms in shape, becoming flexible but still retaining its approximate solid form.
Casting: The glass melts, becoming a viscous liquid that takes its shape from that of its containing mould.
It is common for one piece to use several of these processes in turn. Coloured glass may be fused together to make a composite multi-coloured sheet. This glass is then cut cold and re-assembled in pieces, which are then fused back together. The piece is finally slumped into a mould to shape it. Glass is usually worked for only one process in a heating cycle. Where a piece requires multiple cycles, it is returned to a lower temperature between them.
What is “Tack fusing”?
Tack fusing is the joining together of glass, with as little change to the shape of the pieces as possible. Tack fusing may be used either decoratively, or to assemble a large piece of glass from laminations.
Where tack fusing is used to apply small decorative details to a larger piece, it is often desired to partially melt the small pieces so that they change shape (usually becoming more spherical, under the influence of surface tension), but without changing the shape of the carrier piece.
What is “Full fusing”?
Full fusing is like tack fusing, but the temperature is higher so that the fused pieces begin to coalesce. In the complete case, decorative additions to a surface are absorbed entirely into it and the surface becomes flat again. It is usually done for decorative effect.
What is “Slumping”?
Slumped glass is heated to the temperature at which the glass softens and begins to deform. It may either bend along a single curvature or, if heated sufficiently, may become elastic enough to stretch and curve to follow a compound curvature, such as a bowl.
What is “Mould slumping” then?
Mould slumping begins with a sheet of flat glass placed above a ceramic, usually unfired, mould. When heated, the glass slumps into the mould under its own weight.
These moulds are usually commercially made and are offered in a range of standard shapes and sizes: bowls, trays etc. For custom pieces, a glass worker may also make a specialised or temporary mould as a one-off.
To avoid trapped air, the mould is perforated with a small vent hole. The hot glass otherwise forms a good seal with the lip of the mould and an air bubble is trapped. Such a trapped bubble often causes problems - when cooling this air may contract to form a partial vacuum that is enough to break the glass. As the glass is not heated enough to become liquid, this air cannot escape as bubbles and so venting is required.
Kiln wash, shelf primer, Boron Nitrite or Universal Mould Coat is used beforehand to prevent the glass sticking to the mould.
How do you make a “slumped vase or vessel”?
A mould for free-fall slumping is in the form of a ring with a central opening. When heated, the glass falls through this opening and forms a bowl. Depending on the temperature and time, this bowl may be shallow or deep. If a kiln shelf is placed beneath the ring mould, this catches the falling glass and gives a vessel with a flat base. Free fall slumping is used to make taller vessels with steeper sides, such as vases.
What does “Draping,” mean?
Draping is a variety of free-fall slumping, where the mould former is placed in the centre of the piece and the outer edge falls under the heat. As this outer edge is unconstrained, it tends to fall in large folds. The edge is thus highly uneven, although a carefully draped piece may still retain perfect symmetry. For this reason draped pieces are often used as vases or wavy-edged bowls, but are difficult to use as a more functional vessel.
What is “Glass Casting”?
Casting is the process where the glass begins to melt and behave as a liquid. Its shape is now constrained entirely by the mould and the previous shape is lost. Glass is viscous though and the soft glass does not flow through the mould. Variations in the glass are thus preserved in the final piece, so colours and inclusions present beforehand may still remain in the cast item.
Glass may be cast from either billets (solid ingots), sheet, loosely stacked pieces of glass (these are usually used with a low-temperature casting, so that their boundaries remain deliberately visible afterwards) or frit, and ground or powdered glass.
Moulds for casting may be either re-usable ceramic moulds, or else a one-use ‘investment' mould of plaster
What is “Pâte de Verre”?
Pâte de verre (literally glass paste ) is cast from powdered frit, mixed with a glue binder. This allows the paste to be applied to the sides of a large mould in a thin layer. When fired, a thin-walled vessel is formed. The transparency of the finished casting depends on the size of the frit used: fine powder produces an opaque cast; medium or coarse frit may be used to cast a transparent piece.
What is “Fire polishing”?
Heating the edges to smooth and round them.
What is “Combing”?
This is one of the few processes that involves manual work on the hot glass while still in the kiln. While the glass is molten a pattern is formed on the surface and then trailed into ‘feathers' with a pointed metal rake. The glass is like toffee and this technique is not for the faint hearted or temperature sensitive!
What is compatible glass?
Two glasses are compatible if they can first be fused together, and after proper cooling to room temperature, have no undue stresses in the finished piece that will lead to fracturing.  The compatibility of a particular glass is a function of both viscosity (resistance to flow) and expansion (change in size as temperature changes).  Two different glasses can be compatible if the viscosity and the expansion are the same, or if a strain caused by a mismatch due to viscosity is canceled out by the strain caused by the mismatch in expansion.
What is the difference between glass and glaze?  
Although pottery glazes are true glass, glazes are meant to be applied as a thin coating on the surface of the pottery.  To hold their position on the surface of the pottery; they must be quite stiff when melted.  The type of glass used in fusing is fairly runny when molten and it is applied mainly in the form of cut sheets.  Glazes are made by blending the un-melted, raw materials and spreading these blended materials on the surface of pottery, where the glaze is melted into place.  Glass, on the other hand, is melted first in a pot of molten liquid material and then fashioned into objects and sheets.  A glaze on the surface of pottery is in slight compression.  This means that there is stress on the surface of ordinary pottery.  If you were to make the glaze thicker the stress would be too great, and cause crackling of the glaze and in extreme situations cracking of the pottery.
Can you cut and fuse the glass more than once?   
Fused sheets of glass can be cut by a glass cutter if thin enough.  Thicker slabs (more than 6 mm thick) are cut with a wet tile cutter using a continuous diamond edged blade. Cut shapes can be refused into new compositions.  New layers of glass can be added and fused to provide shape color and texture. Some seemingly simple compositions may require up to a week or more in the combined re-firing processes.
What is “dichroic” glass?
Stunning, dramatic, eye-catching and dazzling.
Dichroic means two colors. When this glass is viewed from different angles, it appears as numerous colors. The word "dichroic comes from two Greek roots, "di" for two and "chroma" for color and literally means two-colored. It can split a beam of light into two beams with differing wavelengths. This glass appears to be different colors when viewed from different angles or in varying degrees of illumination.
This glass has thin layers of chromium, silicon, titanium, aluminum and zirconium depending on the color. The color isn't in the glass, but in a coating that is put on the glass in a vacuum chamber at high temperatures. The effect of this coating resembles an oil slick on water.
Dichroic glass was a product created by the space industry (NASA) and was used as an interference filter. Manufacturers coat the surface of a piece of base glass, either clear or black, with layers of the metallic oxides causing the iridescent effect on the glass. There can be at least 17 thin layers of interference in this glass, and can change color depending on the angle it is held at. It is very expensive to make and buy which is why pieces containing dichroic glass cost more.

The process - how are the pieces made?

Where do you make your fused glass pieces?
At my glass studio in Bronte where the glass is fused, shaped and slumped. The studio has a kiln capable of handling sheets of glass up to 40 x 40 cms in size.  The glass studio also houses the cold working equipment for grinding, polishing and sand blasting. 
Are your pieces the same?
Due to the difference in co-efficiency of glass, no two glass fused products will process the same. This means that every item you buy from us is completely unique which is what makes working with glass so exciting!
Are all the pieces handmade?
Yes!
Where does the raw material glass come from?
We buy our art glass from specialist stores in Leichardt and Canberra. The Spectrum and Bullseye companies in the United States manufacture the glass. We sometimes use ‘plate' glass (from old windows) and old bottles of wine, spirits, beers and jam jars can also be used to create fused and slumped glass art.

How is a piece of fused glass made?
Most contemporary fusing methods involve stacking, or layering thin (3mm) sheets of glass, often using different colors to create patterns or simple images. The stack is then placed inside the kiln and then heated through a series of ramps (rapid heating cycles) and soaks (holding the temperature at a specific point) until the separate pieces begin to bond together. The longer the kiln is held at the maximum temperature the more thoroughly the stack will fuse, eventually softening and rounding the edges of the original shape. Once the desired effect has been achieved at the maximum desired temperature, the kiln temperature will be brought down quickly through the temperature range of 815°C to 573 °C) in order to avoid devitrification. It is then allowed to cool slowly over a specified time, soaking at specified temperature ranges, which are essential to the annealing process. This prevents uneven cooling and breakage and produces a strong finished product. This cooling takes place normally for a period of 10–12 hours in 3 stages.
The first stage- the rapid cool period is meant to place the glass into the upper end of the annealing range 516 °C. The second stage- the anneal soak at 516 °C is meant to equalize the temperature at the core and the surface of the glass at 516°C relieving the stress between those areas. The last stage, once all areas have had time to reach a consistent temperature, is the final journey to room temperature. The kiln is slowly brought down over the course of 2 hours to 371°C, soaked for 2 hours at 371 °C, down again to 260 °C which ends the firing schedule. The glass will remain in the unopened kiln until the internal temperature equals room temperature.
Note that these temperatures are not hard and fast rules. Depending on the kiln, the size of the project, the number of layers, the desired finished look, and even the brand of glass, ramp and soak temperatures and times may vary. Fusing schedules can be anywhere from 24 to 72 hours depending on glass thickness (number of layers) and technique being used.
What can be made with fused glass?
Fused glass techniques can create almost anything, within reason! Typically though fused glass objects are functional (plates, bowls etc), sculptural (panels, free standing and so on) and jewellery, notably beads. Producing functional pieces generally requires 2 or more separate firings, one to fuse the glass and a second to shape it.
The possibilities are only limited by your imagination.  Some of the applications are: sculpture and unique vessels, windows that allow light to pass through while providing privacy at the same time, table tops, room dividers, backsplashes, wall panels, screens, cabinet door inserts and cabinet knobs.
Can you design something special for me on commission?
Yes, of course. Contact us and we can arrange to commission a piece personal to you whether it is fused glass, slumped or dichroic glass; functional, utilitarian, sculptural, spiritual, aesthetic; personal or corporate.
What influences and inspires your work?
My inspiration is taken from many forms of nature. I watch the ocean and the land and the changing light and seasons to inspire me. I am also heavily influenced by modern and contemporary Japanese printmakers.
Are the art glass pieces “food safe”?
Yes.
The official answer from the glass manufacturers is, “All tested compatible glasses have been tested by the FDA for food bearing surfaces and were determined to be suitable.” If we have added other processes or compounds to the items, for example paint, stains, decals, glazes, metals etc. we check that these items are also approved for food bearing surfaces. In addition it is of the utmost importance that dinnerware items be properly annealed, especially if you're going to place hot food on them.
How do I look after my new art glass piece?
Your piece is not oven, microwave, freezer nor dishwasher safe. The piece has been annealed correctly and is relatively robust but do not place very hot items on the glass trivets or really hot food in the items. Wash by hand and do not use an abrasive scourer or cleaning agent. Dust carefully.