Written and translated by Ole Victor

Sand casting glass is a quite simple method but with great artistical oportunities. Tools and materials are very basic with the exception for the furnace itself.

Sand moulds can be shaped in many ways, from simply digging by hand to sophisticated methods, like shaping the sand around a modell. The mind is the limit. The making of the mould is not very time critical and therefore suitable for non-experienced artists.

While practically any sort of sand will do, the sand is sometimes carefully selected and prepared. Usually sand with varying grain size is easier to build and form. The addition of 2-3% of bentonite further enhances that property. Water is added until the sand is buildable. Too much water should be avoided since it makes the vapors blow large and uncontrolable boubles into the glass. The sand can be re-used again and again.

The artistical freedom and oportunities with sand casting are virtually unlimited, which is very well proven by Bertil Vallien and others.

While casting, many sorts of decoration can be applied. The surface of the mould can form relief patterns. It can also be stained with powder glass colours or prepared with graphite depending on the desired surface. Items made of copper, glass or sand can be introduced during the process, forming the interior of the piece.

Smaller objects can be removed from the sand and put in the annealer when they are cool enough to keep their shape. Larger pieces are put in the annealer while still in the mould.

While sand casting is perfectly possible at blowing temperatures (1100 – 1150 C), a higher temperature of 1250 C and above gives greater detail and less separation between layers of gathers.

The most important limitation is size. Larger (thicker) pieces must be annealed very long times, sometimes months.