We winemakers have a love/hate relationship with our oak barrels. They are, generally speaking, indispensable to our craft. Even wineries (such as ours) that don’t use a lot of new oak barrels (which tend to impart more overt barrel-related aromas and flavors to the wine) still likely use a lot of neutral oak barrels. While a neutral barrel doesn’t impart its own flavors to the wine, the simple fact of oak being slightly porous allows tiny amounts of oxygen to seep through the barrel, contributing to the maturation of the wine inside. (We’ll talk more about the role of oak barrels in winemaking more generally in a future blog post.)
This post is about one of the inescapable operational realities of oak barrels: Because they are porous, barrels experience evaporative losses over time, and we have to top up every single barrel on a regular basis. Failure to do this will result in larger and larger air pockets at the top of each barrel, and exposure to too much air can have unpleasant consequences for the wine. The most prevalent is the potential flourishing of aerobic bacteria in the Acetobacter genus — which will produce acetic acid (vinegar!) and ethyl acetate (nail polish remover!) in the wine. It goes without saying that this is a less-than-desirable outcome if you’re in the business of making fine wines, and it’s very easy to prevent by following a disciplined process of keeping barrels topped.
We try to top our barrels no less frequently than every six weeks. We do this by pulling wine from containers that we have on hand to store sub-barrel volumes — colloquially, these are often referred to as “breakdown” vessels. We use 30-gallon half barrels, 30-gallon polyethylene tanks, 15-gallon kegs, and 5-, 3-, and 1-gallon glass carboys for breakdown at Prospice. Wherever possible, we top “like with like” — for example, using a carboy of Les Collines Syrah to top the barrels of Les Collines Syrah. If we don’t have breakdown of a particular wine, we may use a very similar or compatible wine to top it — for example, topping Golden Ridge Vineyard Merlot with Bacchus Vineyard Merlot. It generally requires a very small amount — a liter or less — to top each barrel, so the overall composition of the barrel is for all intents and purposes not materially altered.
The mechanics of topping are actually pretty efficient. If our topping wine isn’t already in a keg, we transfer it into an empty one, and then attach our topping rig — this is a long hose with a trigger valve on one end, and a fitting on the keg that lets us attach a high-pressure nitrogen cylinder. The keg is pressurized with the nitrogen (which is inert and prevents the wine from oxidizing during the topping process), and we can simply hop from barrel to barrel to top each one off quickly and efficiently.
After we’re done topping, we may have to further break down whatever topping wine we have left. If we started with a full 15-gallon keg, and used 5 gallons of it to top barrels, we then break the keg down into two 5-gallon carboys. Everything is put into vessels that can be filled as full as possible to minimize air contact. If we have a breakdown vessel that has significant “head space” (air at the top), we add argon gas to that container and seal it — Argon is inert, and is much denser than air, so it will displace the atmospheric gases from the surface of the wine. At least twice a week, we re-gas any partial vessels with argon to make sure they stay protected.
Topping is just one of many repetitive and seemingly mundane tasks that we must perform to take care of the wine, but our meticulousness is at the core of what we do to bring your the best possible wine we can make. Speaking for myself, topping is one of my favorite things to do. It gives me an opportunity to “check in” with every single barrel in the cellar, giving it a quick sniff and visual inspection. The sound of the wine flowing into a barrel as it gets closer and closer to being full has a very unique musicality to it, and you can almost reach a point of being able to get a barrel perfectly full just by ear.
I’m off to ski for a long weekend — my last chance at a break before our big push to bottling and opening the tasting room! Our next blog post will focus on some of the tasks involved in that push, such as making sure our Viognier and Rosé are heat- and cold-stable.
Thanks for continuing on the journey with us, & we look forward to sharing Prospice wines with you very soon! Cheers, Jay