|Release||7 February 2012 (Update)|
|High alch||0 coins|
|Low alch||0 coins|
|Examine||It looks thicker than normal glass.|
Robust glass is an untradeable resource created by melting red sandstone in a robust glass machine, located south-west of the Mud Bath in Oo'glog or the Ithell district of Prifddinas. It can be accessed after As a First Resort.
Making robust glass from sandstone has no Crafting requirement and grants no experience. Players with level 89 Crafting can create potion flasks from robust glass using a glassblowing pipe to receive 100 Crafting experience. Players may boost their level if below 89 but can not be assisted.
An update in May 2017 changed the colour from purple to yellow.
It is possible to obtain Strange rocks through making flasks.