The soft, Easter-worthy colors of the sea glass in this photo encouraged me to make this week’s column a second installation of our color-by-color guide to sea glass – not exactly a natural phenomenon, true, but we can make a case for taking on the topic.
Today’s colors: seafoam green and lavender. The spring pastels look lovely in a jar together, and, interestingly enough, you could say the history of the two glass colors is linked.
What it is: A piece of seafoam green sea glass isn’t an uncommon find, but the color is so attractive that I always pocket a piece in this shade when I find one. A batch of glass will naturally have a pale bluish green hue because of the widespread presence of iron impurities in glass’ main ingredient – sand.
Unless glassmakers were looking for their product to have a special color, they’d leave it in its natural seafoam state. As a result, there’s a huge amount of glass out there in this color – old and new, and mostly mass-produced – from old windshields to modern vases.
Lots of beverage bottles have been made in this shade over the years. After all, why bother tweaking the color of what’s essentially a disposable item? But seafoam green is probably most associated with a single kind of soda bottle: Coca Cola. For decades, the classic Coke bottle was made in varying shades of this soft color, with the intensity of the green varying with the location of manufacture.
So many were made and tossed in the last century that it’s highly likely that any given piece of seafoam green glass started life as a Coke bottle.
To rid their product of its natural iron-green tinge, 19th- and early 20th-century glassmakers turned to manganese. The naturally occurring metal clarifies the glass, cancelling out the effects of other metal impurities.
But glass with manganese in it won’t stay clear forever. When exposed to ultraviolet light, it will gradually turn a pale shade of purple. Sea glass collectors love to find these “sun-colored” shards that have been altered by exposure not just to wind, sand and waves but also sunlight.
Where to find it: As discussed before, sea glass is less common everywhere these days, and the Jersey Shore is no exception. Anti-litter laws (a good thing!), the rise of plastics and beach reconstruction have all made the man-made gems more and more rare.
But if you’re on the lookout for seafoam green glass, our beaches are good places to look. Shorelines with a long, strong history of tourism often have proportionally more seafoam, thanks almost entirely to generations of summertime beachgoers’ love of cold Coca Cola. Resorts would often dump their glass refuse offshore, and plenty of day trippers would toss bottles into the waves. I’ve found more Coke bottle pieces on LBI than I have anywhere else I’ve collected.
Why bother: Collecting with color in mind offers a wonderful window into the history of the glass pieces you gather.
Wondering about the provenance of the seafoam green piece you picked up? Shape and markings can take you a few steps further. If your piece is dead flat and the color is very pale, you’re probably holding part of an old windowpane. If it has the slightest of curves, it could be from an old car windshield.
Thicker seafoam shards with pronounced curves are almost certainly from beverage bottles. Coke bottle pieces can be easy enough to identify, because of recognizable bulbous markings and, occasionally, the Coke name spelled out in script.
If you’re lucky enough to find a lavender piece, hold onto it. The glass is relatively rare, in part because the manganese that ultimately degrades into the pale purple shade has always been a pretty costly mineral. When World War I broke out, the metal was directed toward the war effort, and glassmakers turned to other materials to manufacture clear glass. As a result, your lavender seaglass pieces are probably very old – pre-1915.
