Flint Glass and Canary Flint Glass.

 FLINT GLASS:

Flint glass is one of those rarities to collectors, so that in some cases, people don’t even know what to look for, or that they can look for it..
The Welkers, in their book describe it as a term for a specific type of glass.  The name was said to have been derived from the fact that in England in the late 17th Century that flint, a form of hard, very pure, natural quartz, was calcined and pulverized to make silica as a main ingredient in glassmaking.  Use of this pure silica makes glass highly refractive and brilliant.

This formula from the English also used oxide of lead as an ingredient, and as such there is according to the experts, an " anynonymous relationship between the terms Flint Glass and Lead Glass, although flint and lead each have a different role in glassmaking."
Technically the term lead glss is the most proper when describing flint glass in the US.
The type of glass th contains lead osxide as a principle component usualy didn’t contain the raw flint materials, so that the term, Flint glass is actually a misnomer in the US.

First made at Hobbs, Brockunier and Co. in Wheeling WV in 1864, lime was used in the production and caused that the glass that was yellow had a more pale tint to it  and included a sort of green cast when it was seen in the sunlight.
  
Between 1864 and 1900, the term VASELINE came into use as a way to describe this canary-lime glass color, but it too wasn’t actually the same as the older canary flint glass. The true Canary Flint had a much more bright bold yellow color than the new lime based  that wasnt really the same as canary flint  glass.
That lack was a topic of serious discussion during those times and the term vaseline &copy was a dealer term that mor than just  a few people had objections to.

 OLD GLASS,a book written in those times, which was Copyright 1924, by N. Hudson Moore states,regarding the glass:
"All the pieces shown in figure 207 are in this royal purple and canary yellow, which, by the way, no real collector would ever call vaseline, a dealer’s term."   This is just about the oldest book that uses the term vaseline to describe that kind of glass.
 
Reyne Haines says that true "Canary flint glass WILL glow bright green under a UV blacklight and for all intents and purposes, is collected by vaseline glass collectors as a "yellow-green glass that will glow green under a UV blacklight, due to the presence of uranium oxide in the glass formula (definition most widely used by vaseline glass collectors). Due to the content of lead in the glass, the glass has a softer feel to it.  The flint glass made before 1864 had as much as 40% lead oxide in it (as compared to todays lead crystal, which generally contains a maximum of 24% lead). Canary flint glass was
also much thicker than the vaseline glass made after 1864, but this was primarily due to the lack of refinement in the glass presses of the day, rather than a necessity of working with molten glass with a high lead content. The glass produced during this time frame also seemed to have had more simplistic patterns, which I also think was  due to the lack of refinement in the glass pressing procedures of the day."
  
Three companies made most of the Canary Flint glss that is found today, those being, New England Glass Co. , Bakewell,  Pears and Co.of Pittsburgh Pa and the Boston and Sandwich Glass Co. of Sandwich,  Mass. although notations do state tht a couple other companies did make some smal amounts of it.

 
This most illusive type of glass will of course be a bit difficult to find..  and you’re going to hve to do your research to make sure of what you’ve got, particularly if the photo isn’t a great one and its not labeled or categorized as canary flint glass. You will hve time to have a good look at the photos and take them to someone who may know a bit more if you watch the auction and then begin bidding.

The best place to find it, of course, will be those online auction sites, such as ebay, but if you search it out and use those key words, of course the price will be higher. Often its misrepresented as art glass, depression glas or something else, in which case you’re going to get a good deal.