No Matter How Long You Soak, You Still Have to Scrub

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Always Clean Your Carboys!

Never let your carboys get this dirty

Cleanliness Is Next to Goodliness

Nothing can spoil a batch faster than bacteria or wild yeast living on the remains of a previous effort. That’s why winemakers are always vigilant with rinsing bottles after they’re empty, and slosh sulfite around their equipment with great abandon. Keep your equipment and bottles free of debris and treated with a bacterial suppressor like sulfite solution and it will always be ready to go, right?

Frog don't care. Frog says scrub. 

Sadly, no—in fact this regimen can leave your equipment a cause of failure, rather than a source of success. Simple rinsing may remove visible residues from surfaces, but after repeated exposures to batch after batch of wine even the ultra-smooth surfaces of glass carboys will develop an invisible layer of colloids and proteins, sometimes described as a bio-film.

Pro Tip: don't Google pictures of dental plaque.

This film is analogous to the film that develops on your teeth. And, just as in keeping carboys clean, if you only rinsed your mouth after eating, and perhaps took a swish of mouthwash, you would, in a very short period, find yourself with a serious oral hygiene issue.

PBW - Tim's favorite cleaner

PBW - My favorite

Soaking Isn't Enough

Even soaking equipment in quite powerful oxidizing  cleaners (chlorine-based powders, peroxides or bleach) or powerful reductive agents (sodium hydroxide/caustic soda) won’t completely remove biofilms. This requires the mechanical action of scrubbing to remove the film. Again, we can go back to teeth: even if you rinsed with very strong mouthwash, you still need the mechanical action of brushing to remove the debris from tooth surfaces to be free of debris, much less kissing fresh.

Another way to think of this is your plates and cutlery. If you used them day after day, week after week, month after month, they'd get gicky. Soaking them in a sink full of soapy water and then rinsing them might work for a while. Soaking them in a strong oxidizing or reducing cleaner and then rinsing might work a while longer. But eventually you'll get a layer of awful film that just won't come off, and it's all fun and games until somebody gets food poisoning--or until your batches start going off on their own.

Oops - Can you spot the winemaking mishap?

How many times do I have to tell you: the wine comes out first!

You Have to Scrub Your Equipment

One of the ways I’ve illustrated this in the past is a demonstration I did with a very high-volume consumer winemaker. He had made hundreds of batches of wine over a period of a couple of years (big extended family, thirsty friends, lots of parties—he was very popular!) He was methodical, thorough and meticulously clean, but he had thought that a few minutes soaking with cleansers and sulfite treatment was enough. I got him to use a very powerful oxidizing cleaner. At my direction he soaked all of his carboys in a strong solution for 20 minutes, scrubbed them with a brush and left them overnight. In the morning when he saw the layer of muck—it looked like sticky brown algae—in the bottom of his carboys, he was convinced of the power of scrubbing, if not a little queasy.

Primary fermenters with lids, and the new (and wonderful!)  Big Mouth Bubbler® Fermenters are a snap to clean: a soak in cleanser and then a scrub with a cloth or a soft brush will take care of even the most stubborn film and goo. The traditional method of scrubbing a glass carboy or bottle has always been with a long-handled, round-bristled brush. Not only do these reach to the bottom of the vessel, the wire handle can be bent at an angle to scrub the inside of the upper neck and shoulder.

Plastic carboys have always presented a bit more of a challenge: the stiff nylon bristles of a carboy brush can actually leave tiny scratches and imperfections on the surfaces. These don’t render the carboy useless, but they do provide very convenient places for bacteria and bio-films to hide out from your cleaning efforts, kind of like a trench or a foxhole in a military engagement. Once the scratch is established, it’s very unlikely that any brush bristle will enter it at the exact right depth, angle and direction to brush it clean. Over time the scratch can become a home for potential spoilage organisms.

Using a Soft Cloth on Carboys

Good news though: the scrubbing you need to do doesn't actually require vigorous mechanical action or hard bristles— if you’ve soaked your equipment with a good cleanser for a sufficient period of time. With the bio-film softened by the combination of the universal solvent (water, king of solvents!) and further disrupted by oxidizers or reducers, and surfactants in the cleanser, a mere gentle swishing with a soft cloth will take care of it. And it’s easy enough to stuff a clean dishcloth or small rag down the neck of even a glass carboy and then to get down and roll it around on the floor.

To make the soft-cloth process most effective, you need only a few cups of liquid inside the carboy. Too much liquid and the cloth will simply float around above the surface. Too little and the cloth will tumble and hop around. Basically, a very sloppy-wet cloth with enough water to keep it lubricated and flowing over the surfaces is what you’re shooting for. Once the cloth is stuffed down the neck of the carboy you can (very carefully!) hold it upright and do a bit of a swirly move to get the bottom clean. After that, place it on its side on an open surface, soft enough so it won’t scratch the outside of the carboy, and with enough space so you don’t accidentally roll it against another object that could damage or break it. A minute of rolling it around and you can pick it up (again, careful!) and hold it over a sink so you can repeat the swirly move with it upside-down to remove films around the shoulder and neck.

Cool Equipment for Cleaning

The Carboy Cleaner - a Soft Brush that fits onto a drill


If you’re feeling ritzy, or if you've got more than one or two carboys to clean out at one time,  The Carboy Cleaner is a soft-cloth scrubbing brush setup that is intended to fit onto the end of a drill. There are two heavy flaps of cloth that are just slightly larger than the inside of standard carboys. When the paddle-brush is inserted into the carboy and the drill is actuated, the flaps extend like a propeller, softly scrubbing the surfaces gently, but very thoroughly and extremely quickly. The unit will do the top and bottom of the carboy just as thoroughly, and in less than 30 seconds, you’ll have a shiny clean carboy, without the danger of scratching the surface of even soft plastic.

By far the coolest cleaning system today takes its cues from CIP (Clean In Place) setups commonly used in commercial wineries and breweries. It's impractical to get inside a five thousand gallon tank with a scrubbing brush or a cloth, so tanks are equipped with spray balls, kind of like an omni-directional pressure washer. Using a recirculating pump and strong cleaners, they harness the mechanical action of high-pressure water to scrub the surfaces and remove debris.

Mark's Carboy Washer pumps cleaning solution into your equipment and pressure washes it

The little connectors in front hook up to your hoses--clean their insides as well!

Mark's Carboy Washer is a genius piece of work. Inside a stand that doubles as a sump, a submersible pump is attached to a spray head, which recirculates cleaning solution for as long as you leave it plugged in. Rinse off most of the debris from your carboy, bucket or Big Mouth Bubbler, fill the Carboy Washer with a warm cleaning solution, pop the vessel on, plug it in and let it run for 10 or 20 minutes, and it will be sparkling clean. I almost always follow up with a quick scrub with a cloth or the Carboy Cleaner, but it takes 90% of the work out of scrubbing.

It's Not Rocket Surgery

People have been making wine a long time, much longer than germ theory or the invention of the microscope, but it's only recently that wine has been consistently delicious, and for most of human history people were resigned to drink sour wine at least part of the time. You can make great wine the first time and every time if you follow these steps:

  1. Rinse dirty equipment to remove most of the surface debris.
  2. Use a good beverage cleaner--no home stuff. 
  3. Soak and scrub to get visible debris and (invisible) surface films.
  4. Rinse well.
  5. Let your equipment drip-dry and store it dry and covered (to keep dust out) or upside-down.
  6. Use a sanitizing chemical (sulfiteStar San, or similar) to prevent spoilage organisms. 
  7. Relax--you're doing a great job. Have a glass of wine! 

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