Look for a sticker at the bottom of a piece of glass to determine whether it is Fenton glass. The stickers are typically oval in shape, with scalloped or smooth edges. If the item was manufactured after 1970, you may additionally notice an oval with the name Fenton imprinted into the glass. These items are authentic.
Look for a pontil mark on the bottom of the glass, which Fenton lacks.
Six Tips for Recognizing Fenton Glass Look for a Fenton tag (before 1970), the Fenton mark ("Fenton" in an oval), or "F" in an oval, suggesting that another company's mold was utilized (1983+). There are two types of Fenton glass: clear and color-contoured. Color-contoured Fenton glass has one color inside and out while clear Fenton glass is totally transparent.
Color-contoured Fenton glass is easier to identify because it has a colored area where the glass ends. Clear Fenton glass is less likely to have a colored area since there is no colored material used in its making. The color comes from iron oxide added during production which gives the glass its red, yellow, or green tint.
Clear Fenton glass is more durable than color-contoured glass and can usually be used for longer displays-or at least until something breaks. However, colors can sometimes fade over time if exposed to sunlight or other forms of heat. This is especially true for green Fenton glass which tends to turn brownish over time.
Color-contoured Fenton glass should never be placed in full sun since this will cause the color to fade even faster. Instead, position these windows so they get partial shade from a tree or building.
What makes me think it's Fenton? The bottom of my glass has a rough mark. It's Fenton, isn't it? Marks, Pontil: Fenton will not have a pontil mark on the bottom 99.99 percent of the time. A pontil mark is a mark on the bottom of a piece of glass that indicates where the punty rod was affixed during the glassmaking process. These marks are usually made by small metal rods inserted into the ground near the furnace to provide support for the glass as it cools.
I also noticed some bubbles when I blew on it. That's probably why it broke. Bubbles in glass are an indication of uneven heat distribution during the manufacturing process. This shows there were more areas where the glass was getting hotter than others which caused it to expand more there than elsewhere and thus create the bubbles we see today. Some manufacturers will use special molds to create custom glass items like vases or bowls. Fenton didn't manufacture molds. They designed and built their own furnaces instead. But even they used templates to help ensure quality control. So although Fenton didn't make these specific bubbles, they likely created similar defects in other glasses. Also, Fenton usually uses white glass in its decorative pieces while most commonly red wine bottles are filled with glass made by Lehigh Valley Company. There are some exceptions to this rule, but they are uncommon.
Because Fenton use snap rings, the majority of their pieces will lack a pontil mark. Pontil markings may appear as a chip in the glass, a rough lump, or a dimple in the glass's bottom. These marks indicate where the piece was joined to another object such as a bottle or vase. Without these marks, it is impossible to know exactly which factory the piece came from.
Fenton's production methods changed over time. In an effort to make their bottles more affordable, the company switched to using cheaper materials in 1872. They also stopped making glass bottles and instead used ceramic for most products by 1875. Finally, in 1880, Fenton switched to using plastic for their product labels. These changes can be seen by comparing old and new illustrations of Fenton bottles on my website: http://wwwotr.org/learn/history/fenton-bottle-collectors-guide/.
Even with all these changes, Fenton bottles are still made in the same factories that make them today. There are two types of Fenton bottles: those with snap rings and those without. With no pontil mark, only those bottles with snap rings can be identified as having come from Fenton.
Milk Glass is a generic term for clear glass used for drinking water and other beverages.