Contrary to the urban legend that glass is a slow-moving liquid, it's actually a highly resilient elastic solid, which means that it is completely stable. So those ripples, warps, and bull's eye indentations you see in really old pieces of glass “were created when the glass was created,” Cima says.
Cylinder glass is one type of antique, mouth-blown window glass found in historical buildings dating back to the 1600s. It's also known as wavy glass for the bubbling, undulating imperfections found in the surface of the glass that distort images when you look through it.
Wavy glass is the "cool-looking" glass commonly found in older window panes, doors, and furniture built prior to the early 1900s. Generally, the further back in history you go, the wavier the glass is. As craftsmen improved their methods over time, the wave and distortion became less apparent.
For between $5 and $50, you can often walk away with some old glass. how much you'll spend just depends on the size and waviness of the glass. AGW makes some great wavy glass in several different grades of waviness to help you match the glass to the age of your project.
The second type is called cylinder glass, which was later introduced in the 19th century. Both types of glass used to be made by heating the glass and blowing it thereby forming the ripple effect that contributed to the wavy characteristic of every window pane that was produced during that time period.
You'll most often find wavy windows in homes built before the 20th century, although glass doesn't get wavy overnight. Slowly, the glass in homes built in the early part of the 20th century will also begin to feature this unique distortion. It's somewhat of a myth that wavy windows are due to sheer age.
Properties of Wavy Glass
Glass produced between the 1700s and early 1900s have this antique “wavy glass” appearance. Another name for the old-looking glass is restoration window glass. The distortion and imperfections appear when looking at the glass from angles or looking straight through it.
The texture is created during the glass sheet-forming process. A sheet is formed from molten glass with a roller that spins on itself, while travelling forward. Normally the roller spins at the same speed as its own forward motion, and the resulting sheet has a smooth surface.
According to AntiqueBottles.com, bubbles are rare in glass produced after 1920, so the presence of a bubble may help to date a bottle or window.
Definition of bubble glass
: glass in which bubbles gave been induced during manufacture for artistic effect.
Cylinder Glass and Crown Glass are two types of authentic, mouth-blown antique window glass typically found in historical structures in the United States. Both types employ a blowpipe to shape the molten glass.
If you look at glass in old windows, it can look distorted, apparently because the lower part of the pane is thicker than the upper part. Some people think that's because the glass, which behaves like a liquid at times, has sagged over time due to the effect of gravity. But scientists see through this myth.
oeil-de-boeuf window, also called bull's-eye window, in architecture, a small circular or oval window, usually resembling a wheel, with glazing bars (bars framing the panes of glass) as spokes radiating outward from an empty hub, or circular centre.
Crown glass is a type of optical glass used in lenses and other optical components. It has relatively low refractive index (≈1.52) and low dispersion (with Abbe numbers around 60).
Corrugated glass is one type of industrial and commercial glass that was once used almost exclusively in factories. Because of its strength, and ability to diffuse light and shadow to help increase privacy and security, it was in high demand during the early industrial revolution.
Drawn antique glass (also referred to as “GNA”) is also wavy glass with lines, but no “bubbles.” It is popular in cabinet doors and china cabinets.
Rolled glass is made by pouring molten glass on metal sheets and flattening it with a large roller. The glass is annealed or cooled slowly so it doesn't become brittle. Some rolled glass is made on a double roller table, which presses the molten glass between two rollers.
Tempered glass, also called safety glass, is the smartest choice for windows and other glass structures in your home. Tempered glass is heated and then cooled very quickly during the manufacturing process; this rapid change in temperature makes it about four times stronger than untreated glass.
Three very important types of glass are annealed, tempered and laminated glass. Annealed glass is a traditional glass type that has been cooled slowly. Not suitable as a safety glass, as it breaks into large, sharp and unpredictable shards.
Bubbles appear in the glass because it is blown glass. The shapes are formed literally with the craftsmen's breath. Bubbles are part of the charm of a hand-blown piece and add character to each glass.
If the atmospheric pressure happens to be falling as the water warms, the equilibrium between gas molecules leaving and joining the air/water interface becomes unbalanced and tips in favor of them leaving the water, which causes even more gas to come out of solution. Hence bubbles along the insides of your water glass.
Blenko glass does not possess any maker's marks or identification stickers.