Flint Glass -- Akro Hype Or Something Special?

[Steph]

Just looking at old ads. Here's what Akro said about their marbles in 1928:

We will tell you, now, that you've never seen marbles like them. They are round, roll straight, and hit where you aim them. They won't chip or break because they're made of specially treated flint glass.

So was there something special about the glass Akro was using? Something that made them more sturdy than say a Peltier Rainbo a few years later or a Vitro Tiger Eye or a Jabo Classic?

[bumblebee]

Seems like a statement that could be scientifically tested today assuming someone is ready to sacrifice a flinty and other glassies.

[Steph]

I don't know if flint glass referred to flinties.

I think they were talking about the whole line so I guessed it referred to the onyx and cornelian that year. But now that you mention it .....

I'll have to look for when they first started talking about flint glass and when flinties were introduced.

[Steph]

Well, flinties (and moonies) existed at least since April 1928, per Boys' Life.

Akro said they used flint glass in some marbles as early as 1926, in the booklet All About Marbles. (here's a copy)

Here's the part where I saw they mentioned flint glass -- in the Cardinal Reds: http://i119.photobucket.com/albums/o151/modularforms/Akro/1926_Akro_CardinalReds_Cornelians.jpg

They just called the Cornelians "hard as flint", at least on that page.

[Steph]

Flint glass is described in Encyclopedia Britannica as "heavy and durable". So maybe it really was something special. Seems that in some usages it's what is known as lead crystal. But that's not the only thing which has been called flint glass. So I still

[sissydear]

I have a book about "flint" glass, but I'm not at home now. I'll look for it when I arrive. Flint glass is older than 1928.

[lstmmrbls]

A possible marketing ploy with no actual basis of real chemical composition?? Being that "Flint Glass" was a name with a very broad definition. Time to weigh some marbles.

[ann]

I'll check Hellmers' batch book.

[Steph]

Here's what Wiki said about it, including the source of the "flint" name:

Flint glass is optical glass that has relatively high refractive index and low Abbe number (high dispersion). Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00. A concave lens of flint glass is commonly combined with a convex lens of crown glass to produce an achromatic doublet lens because of their compensating optical properties, which reduces chromatic aberration (colour defects).

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, circa 1662, to produce a potash lead glass that was the precursor to English lead crystal.

Traditionally, flint glasses were lead glasses containing around 4–60% lead oxide; however, the manufacture and disposal of these glasses were sources of pollution. In many modern flint glasses, the lead can be replaced with other additives such as titanium dioxide and zirconium dioxide without significantly altering the optical properties of the glass.

Flint glass can be fashioned into rhinestones which are used as diamond simulants.

Electric Bulbs and Spectacle glasses are made of Flint glass.

Elsewhere I read that the name eventually became so general that any clear, colorless glass was called flint glass. However, I also read that flint glass wasn't always transparent and could be any coloring. So the question is what it meant at the time Akro said it. Maybe Helmer's book will help.

[kbobam]

Although the 'sacrifice' concept could become necessary,

the 'weighing' idea would be a better first choice!