Yes, Andy, that has been my understanding too. Less iron in crushed flint than in sand, so less color in the resulting glass. The Brit was working from images, so color is iffy.
Not really, I was in our public library once and saw a book on ancient roman glass, and thought that some of the bottles and glassware shown was pretty darn good for being made many hundreds of years ago, I wish I could remember the books title, seems to me it was glass blowing techniques of ancient Rome or something similar.....Andy
I was curious about "flint" glass, so I checked Wikipedia: With respect to glass, the term flint derives from the flint nodules found in the chalk deposits of southeast England that were used as a source of high purity silica by George Ravenscroft, c. 1662, to produce a potashlead glass that was the precursor to English lead crystal.
Traditionally, flint glasses were lead glasses containing around 4–60% lead(II) oxide; however, the manufacture and disposal of these glasses were sources of pollution. In many modern flint glasses, lead oxides are replaced with other metal oxides such as titanium dioxide and zirconium dioxide without significantly altering the optical properties of the glass.