|Release date||7 February 2012 (Update)|
|High Alch||0 coins|
|Low Alch||0 coins|
|Store price||Not sold|
|Examine||It looks thicker than normal glass.|
Robust glass is an untradeable resource created by melting red sandstone in a robust glass machine, which 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. While the assist system cannot be used to craft the flasks, it is possible to use temporary skill boosts from as low as level 84 Crafting with a +5 boost from eating a spicy stew. However, attempting to obtain a boost of +5 using this method is not recommended, due to its extreme rarity.
It is possible to obtain Strange rocks through making flasks.