How to cure virgin oak barrels
Wooden barrels shrink when they are dry-stored and that’s perfectly normal. Air dries the wood causing it to shrink which can result in loose hoops and gaps between the staves. To prevent any liquid coming out, the barrel needs to be cured. Curing is a process that hydrates the barrel ensuring its water-tightness. In other words, curing means to wet the barrel with water and allow the wood to swell sealing any gaps. The process can be somewhat different depending on the size of the barrel.
After placing any loose hoops back in place, put your barrel somewhere where is ok to get wet (sink, tub, backyard, front-yard… it really depends on the size of the barrel) and wash it on the outside with water. Small barrels can fitted and washed in the sink, fill 1/3 and shake them, rinse and do the same process one more time all while using hot tap water. This will hydrate the barrel and help get rid of any residue from the inside of the barrel. Small barrels usually seal quicker and this should be enough to seal any barrel that fits in your sink.However, you want to be on the safe side so place the tap in the tap hole, fill up the barrel, place it on the stand and look for any droplets. If there’s none, your barrel is good to go, empty the water and fill it up with whatever you want to season it. In case you see a droplet(s) seeping out, that’s fine, it just needs a bit more time to seal so leave the barrel on the stand, put a cloth or a tray underneath it or leave it in the sink, give it an hour, wipe and check it again. In some cases the dripping will stop within 48 hours.
Filling up the 2l barrel with hot water
When it comes to curing mid-size and large barrels (or anything that doesn’t fit in a sink), hosing it in the backyard works perfectly well. In some cases gaps between the staves can be so wide that water just pours straight out making it impossible to fill up the barrel but there’s a way to fix it.
Traditional European coopers are using a special technique for making the barrel heads (ends) which prevent the occurrence of the gaps on it making it able to hold the water. What you can do is stand the barrel upright, grab a hose and shower the barrel all over and fill the space on the barrel’s head with water then leave it. Bubbles appearing on the barrel's head are a good sign which means that wood is “drinking” the water.
Curing 50l oak barrel
After 30 min flip the barrel on the other head (end) and repeat the process. Next, fill the barrel half way and roll it for few minutes so the water splashes inside, empty the water, rinse the barrel, place it on the stand and fill it up all the way (make sure the barrel is safe from weathering prior to being filled because it’s a pain to move anything more than 20l when full on your own). At this point there might be a drip every now and then but it will stop within the next 24 hours. Once the barrel is sealed and there’s no dripping, empty the barrel and place it upside down on the stand for couple of hours so it can drain any remaining surface water. That would be the final step and your barrel is now ready to be filled with your favorite liquid.
TIP: Avoid leaving your barrel with water for more then two days. Leaving the barrel with the same water too long increases the risk of catching mold, especially if it's half-full. If the barrel needs to be hydrated for longer periods, change the water every 48 hours.