We get asked about demijohns a lot. So I thought some information about Glass Demijohns and where to find them might be helpful. Sometimes, especially in the US, you'll see a large glass blown vessel of this kind referred to as a carboy. In fact the terms demijohn and carboy are often used interchangeably. Whatever you call them, people have often never heard of these containers until they decide they want to make wine or cider. You will sometimes see them made from coloured glass, such as dark brown or green. But the most common demijohns are clear glass. What is a Demijohn? Demijohns are large vessels for fermenting wine, cider and mead. They are often made from thick glass, though you can get PET demijohns too. A demijohn is not a pressure container. So when used in homebrewing, it is important that gases are allowed to escape during fermentation. An exploding demijohn is not a good thing. Handily, the neck of a demijohn is the perfect size for a bored bung and airlock. The airlock allows fermentation gases out of the vessel, but no air (and contaminants) to get in. What volume of liquid does a Glass Demijohn hold? The most common glass demijohn takes one gallon. That is 4.54 litres, or 8 pints, or the equivalent of 6 wine bottles. This makes them perfect for making a 6 bottle wine kit. Important things to remember when using a Glass Demijohn Don't subject the demijohn to extremes of temperature. So if you heat the ingredients, allow them to cool before transferring them to your glass demijohn. And if your ingredients are cold but the demijohn is hot, wait until the glass cools. It goes without saying that a shattered glass demijohn can be dangerous. Don't use metallic (blunt or sharp) objects to clean the internal surface of your demijohn. You may scratch it, and potentially make it more vulnerable to cracking by creating a weakness in the glass. Instead use a cranked demijohn brush which not only won't scratch the glass, but is shaped in such a way so that it can easily get into all the right places to clean. Examine your demijohn carefully before each use to ensure it is not cracked or chipped, and that the surface is free from scratches. A demijohn becomes heavy once filled with liquid. When it's full, don't just carry a demijohn by the handles, hold it underneath as well. Don't ask me how I know this. Where can I get a Glass Demijohn? At this point you're expecting me to say you could buy one from us. However, we don't stock demijohns to buy online, though other companies do. Demijohns are hard to post, they're heavy and they get dropped. We do sell Demijohns made from food grade PET Plastic which are available on our website. We also have second hand demijohns here sometimes. So if you're local to Horam and are after a glass demijohn, drop us an email or give us a call. We may be able to help. If you are not local to us, there are a number of places worth checking: Amazon sell a range of new glass demijohns. Keep an eye out in the Freecycle and Freegle groups in your area. You can sometimes pick up second hand demijohns and other homebrew goodies for free. When we started homebrewing we put out a request on Freegle for anyone having a clear out of their equipment.Look at this lot from a lovely man called John in Uckfield! Plus he gave us a load of wooden wine racking he'd made himself to fit his garage, which fitted perfect in our cellar. Yes, all this for free! Can you believe it! Your local dump may well have some, so it's always worth asking. Ours sometimes have them and charge £1 each. You can often pick up collections of second hand demijohns on Ebay as well as new. If you have a Wilko near you, they also sell new glass demijohns at time of writing. What about Half Sized Glass Demijohns? You may have seen half sized glass demijohns. They're really handy and we've managed to pick up quite a few of them. They are literally half sized, so they hold half a gallon of liquid. I particularly like using them for fermented lemonade, when I don't want to make a whole gallon. But I need to be able to fit an airlock into the vessel. When we first got into homebrew, I asked the suppliers who sold bungs what size we needed to buy to fit the half sized demijohns. Sadly, they don't exist. I was told this size was discontinued a long time ago, and none of the accessories for them are available now either. So if you see one, snap it up! Half sized demijohns are perfect when you're making wine from fruit and haven't got quite enough fruit to make a full gallon. Or for testing a new recipe. Or simply when you don't have enough of your homemade cider must left to fill a whole demijohn, but a half size would do the job nicely. To fit an airlock to a half sized demijohn, simply cut down a full-sized bored cork bung to fit, as we did for the one containing homemade Ginger Beer in this video. Perfect. View this post on Instagram Now we have a pair bubbling together. Ginger beer plus an enormous demijohn of lemonade. #fermenteddrinks #herecomessummer #guthealth A post shared by AlmostOffGridBev (@almostoffgridbev) on May 9, 2018 at 12:31am PDT [This post contains links to our webshop and/or affiliate links to other shops. If you click on them, I may make a small commission at no extra cost to you. Find our disclosure policy here.]