How To Make Pate De Verre

What is Pate de Verre?

Pate de verre is directly translated as paste of glass, which is the technique of pressing glass powders or frits, crushed glass into a mold. It is not a straightforward technique but it provides effective results when kiln casting. 

The use of very fine, sand-like frits gives Pate de Verre its distinctive luster, and enables really specific placements of different colors in the mold. Pate de Verre utilizes a casting method more akin to that of the process of making gold and silver jewelry.

How to make Pate de Verre

Each piece requires a wax model in order to create the desired shape and pattern. This can be in the form of an original wax carving or using an existing mold by pouring the wax around an existing mold or object.

Creating a model for your piece can take anywhere from a couple of hours to 15 or 20 or more to carve out or to make, it all depends on the complexity of the design and the intricacy of the piece.

Wax is a suitable material for models as opposed to other materials as it can be easily removed from an existing mold and is also easier to manipulate and carve than other materials.

Microcrystalline wax, a dark brown wax, is probably most suited to this type of project. The model is constructed by pouring the melted wax into the mold or shape that you wish it to be. It is then carved, smoothed and polished into its final form.

When the model is ready and you are happy with its finished state, glue it down to a surface so that it won't float. You can then build a dam around it using any water resistant material like plywood, sheet metal or clay. You need to then make sure that any seams need to be sealed to prevent the investment (the mold material made from plaster and silica), from leaking out when it is poured around the model.

Pate de Verre Process

Once the investment has dried and is set, remove the dam. The wax model should now be encased in the plaster/silica investment.

In order to get rid of the wax model, steam it out of the mold using heat. At this point the wax model should be gone and the mold is ready to be cleaned up and repaired if necessary. The molds are now ready to fill with glass powders and frit.

Some testing should be done to estimate the volume/weight of glass required to fill the mold. This is obviously dependent on the size of your piece. The different colors you intend to use should then be selected and weighed out into the amounts that you estimated. 

The frit crushed glass that you use should have the consistency of powder or fine sand, so that it can be easily mixed with a binding agent. A dilute solution such as gum arabic is suitable for this technique. The frit should be mixed with the solution to form a sort of glass paste, hence the ‘Pate’ description of the technique. The colored frit is then placed into the mold with small spoons, scoops, and spatulas in the pattern and quantity that you intend.

Creating Pate de Verre glass

Once you have placed all your different colors into the mold, it needs to be placed into the kiln and slowly brought up to a casting temperature of around 1400 - 1550 degrees. It should stay in the kiln until the glass has melted and has filled any of the empty voids within the mold. 

After being held at casting temperature, the temperature should be reduced to the annealing temperature and left to rest. The next step is for the kiln to be slowly cooled over a period of many hours or days. Obviously the period of cooling depends on the size of the piece. 

Temperature control is important here because if the kiln is heated too fast, the mold will crack and the molten glass will run out. Conversely, if the kiln is cooled down too rapidly, the piece will crack. It is best to wait until the kiln has returned to room temperature before removing the piece.

After removing the piece from the kiln, the mold material should now be soft and is carefully removed from the cast glass. The piece then needs to be washed thoroughly to remove any of the investment.

The amount of work required after this point varies with the piece and depends on how well the process worked. Excess glass can be ground off and polished. Any sharp points can be removed with a diamond grinder and the surface can be smoothed.

The importance of heat in this process cannot be understated. Control of the kiln is vital in producing a successful piece. At Soul Ceramics, we have a range of temperature programmable kilns, which can be set to produce the perfect results.

Ensuring that the piece can be heated to the right temperature and maintained and then cooled carefully will ensure a successful project time after time, whether you are producing pieces for a business or as a hobby.

Please do not hesitate to contact us if you require any more information or please view our range of kilns here.

Additional resources on glass fusing

• How to start a glass fusing business
• All about kilncasting
• Common glass fusing issues and their solutions