Science

Crockham Hill CE Primary School

Last updated: 08 July, 2005

Where does glass come from?

Glass is made from sand.

Different sands give different properties of colour and quality to the glass.

The types of sand are mixed together.

Metal oxides can be added to give colour to the glass.

The sand is placed in a stone crucible and heated in a furnace until it melts.
A blob of glass is lifted from the crucible on the end of a long pipe called a Blowing Iron.

The blob of glass is very hot, and runs about like thick syrup. The Glassblower must work quickly to stop the blob of glass falling off the blowing iron.

The glassblower blows a puff of air into the blob of glass. The air expands and the blob of glass blows up like a balloon.

The glassblower uses tools to press the glass into shape before it cools and hardens.
If the glass cools too much, the glassblower uses a furnace to heat it up again.
The glassblower often needs help to finish the piece of glass.

When it is finished, the glass must be cooled. If glass cools too quickly it shatters, so the glass is placed in an oven which cools the glass slowly over a whole day and a night.

Glass sculpture video clip

Glass blowing video clip

Website designed by Andy Lakin-Hall. webmaster@crockhamhill.kent.sch.uk 

Crockham Hill C.E. Primary School, Edenbridge, Kent. TN8 6RP. Tel. 01732 866374

 Last updated 08/07/2005