I keepfinding old blue bottles maybe 70 -100 years old?

Question

How did they make them blue or blueish in color?

Answer 1

Try this informative site.

http://www.antiquebottles.com/color/

Answer 2

Acording to local lore its lead that makes the stuff turn blue

Answer 3

Answerer number one is pretty spot on there - I have amythest coloured bottles and green ones, red ones...All colours and ages. I used to admire my great grandma's collection of coloured glass bottles when I was a little girl.  

But all I wanted to say was that - don't throw them out - clean em up & put them on ebay...bottle collectors like myself love these things, you might be surprised to see what you can make off them.  

Answer 4

First, they need to mix chemicals to form blue glass. That's maybe Titanium Dichloride. Then, with the use of tongs, they'll place the glass on an extremely heat surface then they'll place it into very cold water. As they've done doing that, they have the responsibility to assemble that blue glasses to form blue bottle.