Molten glass

Molten Glass is used in the Crafting and Construction skills as well as some quests to form a number of glass items.

To make glass requires a bucket of sand and soda ash (made by using seaweed on a range). Use either of the two ingredients on a furnace to make the molten glass. You'll receive 20 Crafting experience per molten glass.

In order to make many of the items, you have to use a glassblowing pipe.