Question: I’m looking to find some info on this slag glass lamp. It was my grandmother’s and is over 60 years old. Thank you.
Answer: The opaque bent panels of pressed glass with the creamy, golden swirls in your lamp are typically referred to as slag glass. I use this term only because it has become a widely known, accepted, descriptive term for pressed opaque glass with swirls or streaks, even though the likelihood of it containing any slag is remote. True slag glass is richly marbleized, deeply colored glass rather than glass that is colored with pale swirls or streaks, which is also known as malachite, marbled and variegated glass.
True slag glass was originally produced in England during the last quarter of the 19th century when, simply put, it is believed slag from iron-smelting was added to molten glass to achieve a marbling effect in a variety of colors. This type of glass was used to make all types of glassware, including panels for lamp shades.
American companies (Taylor, Northwood, Dugan, Akro Agate, Westmorland) began manufacturing this type of glass during the late 19th to early 20th century. They also began producing opaque golden, creamy colored glass known as caramel slag that allowed the passage of enough light to give a room a soft, warm, golden ivory glow.
The key to determining if a piece of glass is “true” slag or just a handsome example of pressed glass is to look for glass that is obviously and richly marbled rather than simply colored or streaked.
Your caramel slag glass paneled lamp dates from the 1910s through the 1920s. In your brief description you failed to mention condition or the presence or absence of any marks or numbers on the base of the lamp. This type of information could make a difference in the price of your lamp and without knowing, I must assume there is no indication of the maker on this piece.
Your lamp appears to have six panels and looks to be in very good condition. The wiring is not original to the lamp; originally it would have had cloth covered wire. Rubber and vinyl coated wires were not used until the post-World War II era.
It is a rather nice example of lamps of this type and I would place a value of $300 to $400.