At some point in the next 6-12 months, depending on the type of wine you are making, the wine will have come together enough to be considered finished. If you are making a straightforward, fruity wine that does not have any oak in it and is not being aged on the lees then you will usually have a rounding of the flavors around 6 months post fermentation. If you are making a more complex wine that involves oak and/or sur-lie ageing then it usually takes around 9-12 months before all of the elements integrate properly. In all cases, the ultimate guide to when to prepare the wine for bottling is when it tastes right to you! As soon as you like where the wine is, the end of the élevage/maturation period is nearing, signaling the beginning of the bottling process. Even though we have been testing the wine throughout the ageing/storage period, (along with tracking and correcting any problems), run the numbers a final time. There will be no going back and adjusting the wine once it is in the bottle. The following checklists will help guide you through the steps needed to prepare the wine for bottling.
Pre-Bottling Checklist
If the wine tastes fine and you are happy with the level of clarity and are not worried about stability (see below), an SO2 test is all that’s left to do (see 6.5 & 9.4). Once this has been taken care of, we can proceed to the actual bottling of the wine. However, more likely than not, there will be one or two elements that need our attention before we can bottle the wine:
1) Check The pH/TA: How is the wine’s acidity? If the pH/TA needs to be corrected you should do it now. Keep in mind if you will be cold-stabilizing your wine (see below, 7.3) you will need to double-check the pH/TA once again after the treatment is over because this procedure will cause the pH/TA to shift by an unknown amount.
Note: Using potassium carbonate requires that the fermenter be stored cold (below 40 F) for several weeks after the application. During the period of cold stabilization the tartaric acid drops out as potassium bitartarate. Calcium carbonate can be used in a similar manner and does not require cold stabilization. However it can adversely affects flavor if you are trying to make an adjustment of more than 0.3 pH units, and takes a month to precipitate out of solution.
Note: Every wine will react differently to the same amount of potassium carbonate. The only way to know for sure how much is needed for the desired pH shift in your specific wine is to do a bench trial before treating your entire wine volume (section 9.7).
2) Check the clarity: Is the wine’s clarity satisfactory? If you will be heat stabilizing the wine as part of the pre-bottling preparation (see below, 7.3), then the bentonite/light gelatin fining used in this procedure will have the added benefit of making the wine brilliantly clear. If you are not concerned with heat stability and/or don't mind if the wine is not crystal-clear, then careful racking during the ageing/storage period may be enough to clear up a white wine enough to bottle. Keep in mind that clarity does not equal stability: it is possible to have a crystal clear wine that is not heat stable.
Note: If you are keeping some Residual Sugar in the wine or have had no/partial MLF, we highly recommend filtration at 0.45 microns Absolute (see the next section). This filtration will also serve to clarify the wine.
3) Check the Residual Sugar %: In general, the Residual Sugar (often just RS for short) level does not need to be adjusted for a dry white wine. The juice usually ferments dry and is left where it stopped. However, in cases where RS is desired in the wine, this should be tasted and adjusted just prior to bottling. In addition to having proper SO2 levels we encourage you to consider a sterile filtration in order to guarantee the microbial stability of the wine. If you don’t filter the wine it is possible to pick up a spoilage yeast or bacteria during the ageing or bottling period and any Residual Sugar could be used a food source- allowing them to spoil the wine. Running your wine through a sterile filter (0.45 microns Absolute) as it goes into the bottle will effectively remove all yeast and bacteria from the wine so that the Residual Sugar will remain untouched.
(For complete information on filtration, see 7.2 B below)
4) Check the free SO2: The final treatment: make sure that your free SO2 is at the correct level; adjust if needed (see sections 6.5 & 9.4).
5) Check the stability of the wine: Most commercial white wines are tested/treated to be both hot and cold stable. This allows the wine to keep its taste and appearance unaltered even when exposed to extremes of hot and cold temperature. A stable wine also holds-up better over time in the bottle. Heat stability is done by fining the wine with bentonite, cold stability is done by subjecting the wine to ≤40 F for at least two weeks. For complete info on stability treatments, see section 7.3 below.
Fining and Filtration
Both fining and filtration are treatments that can be done to further polish or finish the wine just before bottling. Fining works by introducing an agent to the wine that physically binds with a targeted element, most commonly tannins or proteins. Once the reaction finishes and the agglomeration precipitates out to the bottom of the vessel, the wine is racked to remove it from the sediment. Filtration works by passing the wine through a material that contains a series of very small holes (or “pores”) similar to a coffee filter. Liquid and particles small enough to fit through these holes are allowed to pass through; particles that are too large get held back and are effectively removed from the liquid. Depending on what is going on in our wines, we may decide to do one, both, or neither of these treatments. It all comes down to our personal winemaking philosophies and whether or not we feel the wine needs maintenance. Let’s take a quick look at both fining and filtration before we move onto bottling.
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