Verdigris in Whiskey: How a Dirty Copper Still Poisons Spirits

Copper, gentle reader, is the most honest metal God put in the ground and the easiest to corrupt, which makes it very like a county commissioner. Every alchemist who sets a pot upon the fire praises its virtues, but fewer of us study its vices. Leave copper in wet air long enough and it grows a coat. You have seen it on an old weathercock, on the sheathing hauled off a ship's bottom at the Portsmouth yard, and on a cent that spent ten years in a dead man's pocket. That slow green is mostly weather: air, damp and time. It is ugly, but it is slow. The true devil comes in with ACID. Then copper grows a crust instead of a coat, and the crust dissolves into whatever liquid stands upon it. That crust is verdigris.

I scoured my worm with vinegar this morning. Ever since, my bear Barnaby has kept his nose at the window like a deacon at a widow's keyhole, sure that he smells pickles. He does not, and none of it is for him. But pickles will figure in this account, so his nose is not entirely a liar.

Green of Greece

The word is French: vert de Grèce, green of Greece. I cannot say why the French blamed it on the Greeks, unless it is that the French blame everything on somebody. In the wine country around Montpellier they made verdigris on purpose for two hundred years. They took the marc, the skins and stems left over from pressing, and let it sour. Then they stacked it in clay crocks in the cellar with thin copper plates between the layers. A few weeks later they scraped off a crust as green as a mallard's neck and sold it by the pound to painters, dyers and apothecaries.

Mark that experiment, brother distiller, for your own sour mash will perform it in your pot if you leave it there overnight. The only difference is that the French had the decency to charge for it, while your neighbor with the filthy pot gives it away free in a jug.

There Is Death in the Pot

The physicians have long known the stuff. Old surgeons put verdigris in a salve to eat away proud flesh and corns, and they knew perfectly well what it would do inside a man. In 1820 Frederick Accum, a German chemist living in London, published a book on how grocers and confectioners were poisoning the public. On its title page he printed the words of Scripture: There is death in the pot. He meant pickles. The London grocers were greening their cucumbers in copper so they would look fresh off the vine, and Accum caught them at it. Thirty-odd years later a Dr. Hassall went through the London shops with his microscope and his chemicals. He published in The Lancet and found copper in pickles and bottled fruit up and down the city. The great Orfila of Paris, the poison doctor, taught the world that a man who has swallowed copper salts should have white of egg poured into him. Our country doctors still give egg whites and milk and send a boy running for the doctor. In my experience you had best send for the man's prayers as well.

I have seen copper colic. First the patient tastes brass, as if he had been sucking a doorknob. Then his belly burns, then it gripes like a sack of cats, and then he heaves up a green-blue matter the color of the ditch behind a dye works. After that he purges from the other end with equal enthusiasm. A small dose leaves a man wishing he were dead, and a large dose spares him the wishing. Nor is New England any better than London. Half the receipt books in Merrimack County told a woman to scald her cucumbers in a brass kettle to green them, and the other half warned her that it would kill her husband. I am told some women read both and chose accordingly.

How Copper Gets Into Whiskey

There are three roads, and every one of them is paved with sloth. The first is sour mash. A mash or wash that sits too long in summer goes vinegary, with fruit flies at it and the mother of vinegar growing on top like a drowned man's skin. Run that in a copper pot and you are feeding acid to metal. The second is the leavings. A tired man who has taken a few honest samples leaves his spent mash and backset sitting hot in the pot overnight. By morning the acid has been chewing copper for eight hours, and he never rinses it out. The third and worst is the worm. The condensed spirit trickles down a coil crusted green inside, picks up the copper, and drips from the spout with a blue cast like skimmed milk. Then there is the plain fool who STORES his cider or brandy in a copper kettle because, he says, it was born there. When Mr. Lincoln's levy made honest liquor dear, such cheap jakes bred like rabbits in a hayloft, and the Concord doctors saw more copper colic than they had seen in a generation.

Here, then, is the still-keeper's duty. Copper is the only part of this craft that will do you a kindness if you treat it right and poison your customers if you do not. I have been arrested twice for selling spirits and shall sleep soundly if I am arrested a third time. But if I ever green-poisoned a neighbor, I would hang myself from my own anvil horn and save the county the rope.

Tales from the Green Pot

Out on the Barnstead road lived a fellow I shall call Abner, for his mother still lives and has a skillet arm. He ran his mash in an old copper wash boiler that he had not scrubbed since Fort Sumter, and he sold the product as Abner's Emerald, proud of its color. A Concord teamster drank a pint of it at the Pittsfield fair and returned it upon the cattle judge so green that the judge awarded it a ribbon for best vegetable. Last October Abner crept up the turnpike by night to help himself to the copper scrap behind my still-house, which is where Barnaby sleeps. I talked the bear off him with a ham bone and stitched his calf with silk, eleven stitches, for a dollar. Barnaby kept the breeches. In the pocket were three green copper cents, which I scoured in vinegar and stamped upon my anvil. They are the only clean thing Abner ever produced.

Silas 'Hacksaw' McAllister, master coppersmith of our foundry here at Fort Wilkins, has lifted the lid on worse. Two winters back Hosea Pike, who keeps a tavern at Gilmanton Iron Works, sent for him to mend a leak in his copper kettle. Hosea made a decent cider brandy, but he believed the kettle was the brandy's kin, so he poured the whole run back into it and kept it there till spring. By March the brandy tasted of brass doorknob and carried a faint blue cloud. Silas found the kettle crusted blue and green, thick as pond scum in August, and no leak at all. He told Hosea to pour every drop into the ground, for, as he put it, 'Copper is for making it, not keeping it.' Hosea did not listen. He carted the brandy to the spring militia muster and sold it as Saint Patrick's Brandy, green for the occasion. When the captain called present arms, twelve men presented their breakfasts. Nobody died, thank Providence, and Hosea now keeps a stoneware crock.

Silas once had an apprentice named Rufus, a boy with good hands and bad judgment, who wanted the shop sign painted green without paying for the paint. Having heard how the French do it, he packed a crock with apple pomace soaked in vinegar and buried copper offcuts in it behind the stove. Three weeks later he ground the green crust in linseed oil and painted a handsome sign. Then the neighbor's goat licked half the S off McALLISTER and lay groaning, foaming green and leaking green, until milk and raw eggs brought her round in two days. Leave sour mash in a copper pot overnight and you have made Rufus's crock. The pot does not know the difference, and neither does the man who drinks from it.

Silas reads green the way a doctor reads a tongue. Green grows only where copper stays wet, so a seam that keeps showing green is a seam that keeps damp, and that seam is weeping. He once held a candle behind such a seam in the dark and found a pinhole too fine to thread with a hair. His father had a test of his own. At the Epsom fair he stood a steel knitting needle, rubbed bright, in a peddler's liquor with a splash of vinegar. It came out tipped red as a new cent, because the copper had plated itself onto the steel, and the peddler left faster than he came. Note this well, though: a bright needle proves nothing safe. It only damns a liquor when it comes out copper.

Reading and Scouring the Copper

Copper shows three colors. Dull brown is harmless tarnish from the air. Black inside the pot, cap and upper worm is mostly copper doing its job, holding back the rotten-egg sulfur stink of the vapor as a dark film. Scrub that film off anyway, so it never flakes into your spirit. Green and blue are the warning, for they mean acid is dissolving the metal. As Silas says, 'Green on the outside of a pot is weather. Green on the inside is negligence.'

My ritual runs as follows. Let the fire die out completely, and never leave a lit still unattended, for the vapor burns. Drain the pot that same day. Feed the spent grain to the hogs only once it has cooled, and pour the backset into a crock or a wooden tub, never back into the copper. Flush with hot water and scrape the bottom with a wooden paddle, never iron, since every gouge becomes a pocket for grime. Next comes ash lye, dripped from my hopper of hardwood ashes and judged strong enough when a fresh egg floats with a piece the size of a shilling showing. It cuts grease, burnt grain and the oily film of the tails. Lye takes skin and sight, so wear greased leather gloves and spectacles, and rinse until the water no longer feels slick. Then work a paste of cider vinegar and salt over the pot with cornhusk and rag, using only the finest sand, with a light hand and only on a stubborn spot. Silas scolds me that I scour too hard. Rinse out EVERY drop of vinegar, three times with spring water. Remember Montpellier: vinegar left standing turns the cure into the complaint. Draw a rag on a weighted cord through the worm, pour warm vinegar and then spring water through it, and catch the rinse in a white bowl until it runs clear. Last, christen the pot with water or weak wash and throw out everything that comes over.

In the cuts, the foreshots and heads, sharp and solvent-smelling and carrying methanol, are thrown out. The hearts are kept, and the oily tails are set aside for another run. Hearts with a blue or green tint mean a dirty still, so shut down and clean again. And all this scouring is wasted on a pot patched with lead solder or riveted from salvaged junk. Use pure copper, joined with rivets, silver solder or proper unions. Let me add that all of this is set down as history and education, for distilling spirits to drink without a federal permit breaks the laws of the United States.

Ashes, Oak Shavings and the Copper Cent

Cletus 'Rabbit' Miller of Wilkesboro, North Carolina, wrote to ask whether hickory ashes or red oak shavings in the thump keg clean out bad heads. Hickory ash makes about the strongest lye there is, and I wager it mostly scoured the keg between runs, which is an honest use. In the pot, an alkali may hold back some of the sour acids. But the bad heads are not sourness, and no handful of ashes will catch them. Only a jar poured on the ground will do that. Red oak is so open in the grain that smoke blows clean through a stave. Its shavings give color and a bitter tannin bite, which is a peddler's trick to make Tuesday's liquor look five years old, and they clean nothing. Use the ashes on the keg and throw the shavings in the stove.

As for the copper cent dropped in the jug to sweeten the whiskey, that is pure horse apples. Whiskey is a little acid, and a month's soaking only brews a small batch of Saint Patrick's Brandy. The cent draws nothing out. It only puts copper in. The so-called copper kick is your stomach trying to escape through your mouth. Keep the cent in your pocket, keep the green off your pot, and let the only copper that touches your spirit be a bright still doing honest work.