When looking to purchase real slag glass, look for the marks of the manufacturer. [5], Slags can serve other purposes, such as assisting in the temperature control of the smelting, and minimizing any re-oxidation of the final liquid metal product before the molten metal is removed from the furnace and used to make solid metal. [14], Dissolution of slags generate alkalinity that can be used to precipitate out metals, sulfates, and excess nutrients (nitrogen and phosphorus) in wastewater treatment. Leaching concerns are typically around non-ferrous or base metal slags, which tend to have higher concentrations of toxic elements. [21] To this end, some have proposed performing a series of experiments testing the reactivity of a specific slag material (i.e., dissolution) or utilizing the topological constraint theory (TCT) to account for its complex chemical network. For example, simple things like a bowl sold for around $20 apiece. It should not have white streaks mixed into the color, nor should it be one solid color. Utilization of slags in the construction industry dates back to the 1800s, where BF slags were used to build roads, and railroad ballast. Serious antique glass collectors will be familiar with "slag glass" which became popular in the late 1800s and is still made today. Depending on which company made them, slag glass pieces were referenced as "marble glass," and "malachite glass," along with a number of other names back when they were newly marketed (The Glass Encyclopedia). It can also be called Malachite glass, in reference to the stone. Vintage glass pieces come in so many different colors, types, and styles with different names for each variety. Fenton, Mosser, Boyd Glass, and Summit are some of the common, modern, U.S. manufacturers of slag glass. Antique Glass Insulators and Their Electrifying History, Antique glass insulators are a low cost but very popular collectible that come in a myriad of fun shapes and colors. The colors of slag glass are also a great way to identify authenticity. The first pressed glass pieces that collectors refer to as "slag glass" were made in the 1890s, using the glass-like by-product of iron ore known asyou guessed itslag. Most homes in the late 19th century and even some older homes today could be found using a slag glass lampshade as decor. (Source). Slag glass is a type of opaque pressed glass that includes colorful streaks that create a marbled effect. Is slag glass natural? I grew up going to antique stores and markets with my mom and grandmother. Most pieces are decorative in nature, sprucing up side tables and bookshelves. Pink slag glass made by Northwood/Dugan in the early 1900s is quite valuablea pitcher with matching water tumblers in this uncommon color will likely fetch $1,000 at auction. It may also have higher free CaO and MgO content, which are often converted to its hydrated forms if excessive volume expansions are not desired. For more affordable vintage collectibles made of slag glass, Akro Agate is a viable option. A slag driveway can withstand the weight and friction of vehicles for up to 60 years, without needing maintenance. When SSRS compares with ground granulated blast furnace slag (GGBFS) from iron making, steel slag contains toxic ingredients such as nickel, cadmium, chromium and strontium. Official websites use .gov Nearby homes similar to 4420 S Alder Dr have recently sold between $360K to $492K at an average of $270 per square foot. Pre-Owned. or Best Offer. Two glassmakers in Pennsylvania, Harry Northwood and Thomas Dugan, were the first to imitate slag glass by mixing two colors of glass together and forgoing the actual slag in 1902. It can be ingested, posing a direct health risk to the communities near the plant, mines, and disposal sites.[23][24]. The base of slag glass is an opaque color, and the streaks are typically a milky white or cream color. (Source). The major components of these slags include the oxides of calcium, magnesium, silicon, iron, and aluminium, with lesser amounts of manganese, phosphorus, and others depending on the specifics of the raw materials used. For Sale: 2 beds, 1 bath 1073 sq. $14.46 shipping. Slag. Other manufacturers quickly caught on and the style rose in popularity soon following its creation. Slag glass is a type of pressed glass that is known for its brilliant and vibrant colors. "Glass slag is similar to obsidian; it, too, consists mainly of silica dioxide. [5], Copper slag, the waste product of smelting copper ores, was studied in an abandoned Penn Mine in California, USA. Nearby Recently Sold Homes. Most manufacturers use up tp 40% to 60% recycled glass content. Slag (middle photo) is much lighter per unit volume than iron meteorites, and is frequently multicolored (blue, red and purple iridescence). This mark is usually made at the bottom of the lamp. Figuring out who made a piece, and how old it is, can be a bit more tricky. Most antique slag items are brown, blue, green, or purple. This does use the broader definition of slag glass that includes white marbling produced through any method. Top Rated Plus. Due to the large demand for these materials, slag production has also significantly increased throughout the years despite recycling (most notably in the iron and steelmaking industries) and upcycling efforts. Modern day slag glass manufacturers in the U.S. include Fenton, Mosser, Summit and Boyd Glass. Get DIY project ideas and easy-to-follow crafts to help you spruce up your space. Vintage slag glass is most commonly found in brown or purple colors with white streaks, but you can also find plenty of green and blue as well. The mosaic glass created in Pittsburgh was a mixture of purple and either white or an opal shade. If the item does not have any names or marks, the piece likely is a fake. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); What is Slag Glass and where does it come from? Lamps, lampshades, and chandeliers were very popular uses for slag glass. Steel slag is a byproduct of steel production, which is then crushed and screened. The value has generally held steady around $5 for a single cup for a few decades. Telling slag glass apart from other styles is actually quite simple. Density: Meteorites are usually quite heavy for their size, since they contain metallic iron and dense minerals. Now, you can find slag glass pieces in practically any color. This alkalinity promotes the mineralization of dissolved CO2 (from the atmosphere) to produce calcite (CaCO3), which can accumulate to as thick as 20cm. Learn more about this project here. Unlike any other type of glass, slag glass is not transparent. When identifying authentic slag glass, pay close attention to the marbling. CMoG 79.4.92. [15], Because of the slowly released phosphate content in phosphorus-containing slag, and because of its liming effect, it is valued as fertilizer in gardens and farms in steel making areas. Slag glass lamps are one of the most sought-after items made of slag glass. Hematite is a common iron oxide mineral found throughout the Upstate. Challinor Taylor & Co. was one of the most prominent American Slag glass manufacturers. The white marbling pattern on slag glass is a dead giveaway. The worth and value of slag glass varies. For many glass collectors, finding a beautiful treasure with antique glass markings is a special treat. It's a human-made rock, but it's not a new technique. Manufacturers experimented with different methods to achieve this malachite-like look. Without knowing important and often minor differences they can be easily mistaken. It has distinctive a distinctive knob pattern and comes in a variety of colors. Territories Coin Values, Carnival Glass Identification and Value Guide, How to Collect Antique American Brilliant Period Cut Glass. Pelletized slag is generally used for lightweight aggregate but can be ground into material similar to GGBFS. This is one of the most common uses for slag glass, and you'll see many slag glass chandeliers and other fixtures in antique shops. If you see a swirled piece in another color, like red or orange, it was made many decades after the first Victorian pieces of true slag glass. It was primarily blue or green and was formerly chipped away and melted down to make glassware products and jewelry. Though it's easily mistaken for other glass products produced around the same time period, such as stained glass, slag glass has its own unique look and slag glass items can fetch a wide range of prices. Here is everything that you could ever want to know about slag glass. This wouldnt be considered slag glass in the strict traditional definition, but many collectors will still use the term to refer to any marbled, opaque, pressed glass pieces. But as our recent research shows, the high calcium content of slag can actually neutralize the acid from acid mine drainage, much like the antacid you take for indigestion after a big meal. Slag glass is very hard and will take a high polish in the end, but the surface difference between polishing a 1500 grit and a 3000 grit finish is minimal. In many smelting processes, oxides are introduced to control the slag chemistry, assisting in the removal of impurities and protecting the furnace refractory lining from excessive wear. 701 South Main Street, #103. The marbling is sometimes compared to tortoiseshell. In some of the most stunning lighting pieces, small pieces of the slag glass were laid out in a metal framework. The ideal thickness of each layer is between 4 to 6 inches. Instead of slag, they mixed purple glass with a white-colored glass that did not contain any iron slag. Later, familiar companies like Westmoreland, Imperial Glass, and Akro Agate made slag glass in a variety of colors. Stone Shop, InSpyritMetaphysical (5,660) $2.50 Vintage Boyd Blue Slag Glass Elephant Head Toothpick Matchstick Holder, Elephant Lovers, Vintage Blue & White Slag Glass HoosierGirlTreasures (83) Also the lack of bubbles . Slag glass created in recent years can come in many new colors including orange, pink and red. Pamela has over 30 years of experience and has been writing for 20 years. In this case, the slag is termed synthetic. Many antique lamps of these periods were made with stained glass, rather than slag glass, and a careful review of the glass opacity and patterns is necessary to determine the difference. Slag glass is often used as a catch-all term for any type of pressed glass that is opaque and colorful, but not all glass that fits this description is true slag glass. 6 Vintage Sneakers That Are Still in High Demand. 12201 Sunrise Valley Drive Reston, VA 20192, Region 2: South Atlantic-Gulf (Includes Puerto Rico and the U.S. Virgin Islands), Region 12: Pacific Islands (American Samoa, Hawaii, Guam, Commonwealth of the Northern Mariana Islands). If the piece is pink, orange, or red it is not vintage. Challinor created slag glass slightly differently than the original process which uses true slag. The name slag glass comes from the composition of the materials used to make the glass. 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