Antique glass fishing net float markers once held fishing nets in place across the globe by the thousands, if not hundreds of thousands or millions. Many of the attractive orbs remain floating around today, washing ashore as collectibles. Should you chance upon one, you might be able to identify its maker. Manufacturers branded many of the globes, and others show the characteristics of certain styles and eras. The Norwegians were the first to manufacture glass fishing floats, but the Japanese fishing fleets dwarfed those of other countries, so there are many more glass floats of Asian manufacture.
Check for any markings, particularly lettering; this is your first indication of the origin of the float. Japanese or Korean glass floats have Japanese symbols, while western and Scandinavian floats have letters you probably recognise. However, many markers have no markings, so you have to rely on style and shape to determine the origin and age.
Check the glass float for any western lettering bearing the marks of the manufacturer. The first glass markers definitely identified came from Norway's Hadeland Glassværk in about 1843. However, recent evidence suggests that Norwegian fishermen might have used glass floats as early as 1790 through 1820. You can identify Hadeland floats by the seal button on the bottom. Other Norwegian glass manufacturers soon entered the market, most notably the Aasnaes and Namsos glass works. The Flesland Glassverk patented grooved egg-shaped floats in 1930, and these floats might have a small F&F mark or no mark at all. Flesland Glassverk also marked its net buoys F1 through F8 or with a dotted F or FG & FG in later years. Christiania Magasin marked its floats with CM.
Look at the colour. Japanese and other eastern manufacturers did not brand their floats, but there are other ways you can identify them. The earliest and most common colours that Japanese manufacturers used were shades of green, because they made the floats from recycled sake bottles. Emerald green, purple, yellow and orange were most popular in the 1920s and 1930s. And no eastern floats have a float line, which is a line around the perimeter of the glass ball as if the two halves were moulded separately and then joined. Globes with a float line are probably European in origin and, although still old, are among the last glass floats produced.
Credit the Norwegians with being not only the first makers of glass fishing floats but also the largest European users of them. Some of the floats got quite elaborate, including grooved egg-shaped floats, non-grooved egg-shaped floats still contained in the fish netting, rare teardrops and fanciful round grooved floats. In very rare cases, a float turns up with wood tags that show the fisherman's initials. If you can identify the fisherman, you might be able to tell where he probably bought his floats.
Look on the side or top of the float as well as on the bottom for markings. Some companies embossed the side or top of the float, or even along the mould line. Those most commonly found are marked with the name of the country; most are European nations.
Consult "Glass Fishing Floats of the World: The Collector Price Guide & Identification Handbook," written by Stu Farnsworth and Alan D Rammer, if you are still stumped. This is the most definitive resource for collectors. The book also prices the globes based on the rarity and uniqueness; you can buy it online and at most bookstores.