The Century-Old Way to Celebrate St. Paddy’s Day Included Drinking Laundry Powder

It's indisputable that St. Patrick's Day has changed a lot since its conception. Once a pretty thoroughly religious holiday created in recognition of the arrival of Christianity in Ireland, it has become—at least in the US—a day with corned beef feasts and cheerful parades, sure, but most marked by massive throngs of drunken frat brothers wearing cardboard leprechaun hats and sloshing beer all over themselves (joining the likes of Halloween and the Fourth of July, once-meaningful holidays that have similarly become boozefests at the hands of the general public).

Just one of the things that has changed—but considerably so—is the making of green beer, one of the trademark libations of the verdant holiday. While nowadays, we're content to throw a couple of drops of food coloring into our mugs and call it a (St. Patrick's) day, people who were feeling festive in the old school (i.e., 20th century) 'teens had another means of painting the town green: laundry whitener.

As noted by Smithsonian.com's Laura Clark, a mildly toxic detergent called "wash blue" or "bluing" used to be the colorant of choice for getting cute with your brew, a tradition that first became popular just over a century ago in the US and not the holiday's homeland of Ireland. Made of a superfine iron powder, bluing was intended to hide the yellowing of white garments by staining them with a very subtle blue cast that would give the appearance of brighter fabric. But by that same principle, a drop of it could turn a golden beer into a Kelly green creation (thankfully, in a tiny enough portion that it won't cause you to drop dead).

The first appearances of green beer were actually in the Big Apple—at a Bronx social club, more specifically, where excited and delighted drinkers marveled at the novelty of the emerald drink that relied on not a colored glass for its color, but a mystical, color-changing additive. The inventor was said to be toastmaster (and coroner—the Irish love their black humor, after all) Dr. Thomas Hayes Curtin, but the tradition has continued through the present day.

And it may go back even further than that, conceptually. There's an old Irish custom known as "drowning the shamrock," wherein Irishmen would hit the pub after local St. Patrick's Day parades and parties and drink shamrocks in their whiskey for good luck. The visual effect might not be quite as striking, but the spirit's in there.

Nowadays, anyone from Betty Crocker to WikiHow could give you tips on how to turn your beer grassy. Betty Crocker somehow extends the process of adding a few drops of food coloring into a lengthy three-step recipe, while WikiHow suggests using a shamrock-green Beerzicle, which is a freezable plastic stick that sort of looks like a cross between a dildo and an icicle suspended in your beverage. As much as drinking around a large, cold, plastic stick sounds charming, if nontoxic food coloring is good enough for the Chicago River, it's probably good enough for your glass.

No matter which method you're into for dying your drink, just remember to keep it food-grade. Should you end up vomiting all over the sidewalk outside of your local Irish pub, it will hopefully be from joyful drunkenness and not from poison.