Toughening It is a requirement that glass be toughened when there is a chance of human impact. For example, doors, partitions and shower screens are a must. As well as enhancing the strength of the glass by five times, when broken, the glass will also break into small fragments ensuring the glass is harmless. Toughened glass is also a grade A safety glass and all of Oneglass’s kiln formed panels are toughened to British or international standards.