Before you go any further...
I've read and accept the Terms of Use and the Privacy Policy.
I accept to receive newsletter and other communications associated with firms of The Explorers Network group'
I accept to receive commercial offers of The Explorers Network partners'.
Thanks!
Vote everyday for your favorite content
SENSITIVE CONTENT
This media contains sensitive content which some people may find disturbing or offensive.
You must be 15 years of age or older to view sensitive content.
Log inBirthday
Content being validated
THE EXPLORERS +
Watch our premium movies
The Explorers + is our premium movie catalog in Ultra High Definition (HD/4K/8K)! Hundreds of videos already available and daily new content on all your devices (web, mobile, tablets, smart TV).
Post content (photo or video) and get 1-month free
OR
Subscribe and support The Explorers Foundation's field actions for biodiversity.
Content being validated
Glass or crystal?
0
0
It is the addition of lead to the silica that determines the nature of the material. The French Afnor standard distinguishes three types of crystal. Between 10 and 24% lead, it is crystalline. Above 24%, it is lead crystal. Finally, superior crystal, such as Lalique’s, exceeds 30%. Added in the form of an oxide, lead gives the glass brilliance. It also makes it more malleable to work with and lowers its melting point from 2,730°F (1,500°C) to 2,550°F (1,400°C). The addition of metal oxides or rare earths during the manufacture of the crystal colours the material. The crystal is ready to be worked 20 to 40 hours after being put in the furnace.
Related content
Médias en cours d’exploration