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How much is enough? (Part 1)

2009 February 3
by Eric Hwang

Determining the amount of wine to make depends on many factors and the desired results.

After talking with friends, reading several books and doing some online research, I realized that there really is very little equipment needed to start making wine. However, if I want to make a pretty good wine or make more than just a couple of cases, then I’ll need to make some decisions now about supplies and some fairly specialized equipment.  

First, I need to decide how much wine I want to make and eventually how many pounds of grapes I’ll need. One case of wine or twelve 750 ml. bottles is about 2.4 gallons. Most prepackaged juice makes 6 gallons or roughly 2.5 cases or 30 bottles. That’s because most carboys (the glass containers) are 5 or 6 gallons in size. But if I really want good quality wine, I really need to start with good quality juice directly from the grapes and directly from the grower. If I’m getting my own grapes, it seems like a lot of driving (from Seattle to Eastern Washington) to just get enough for 6 gallons of wine. I might as well get as much as I can readily haul and store, but I also need to consider the sizes of my fermentation and aging vessels along with where I’ll be storing them and how I can move them. Even a 6 gallon carboy weighs over 55 lbs. when filled.  One of the Macro-T plastic containers that many winemakers use can hold nearly a ton of grapes but weighs over 120 lbs. empty.

I’d like to be able to age my wine in oak. Maybe some new oak, but then the remainder of the time in neutral oak. Mostly to encourage the evaporation process that happens in barrels, giving the wine better body and concentration. Barrels come in all different sizes, from 5 gallons all the way up to 79 gallon hogshead barrels. Most wineries use the standard Bordeaux or Burgundy barrels which are 59 and 60 gallons respectively. I couldn’t just half-fill a barrel and have a large air space in the barrel because that much exposure to air would cause oxidation and the growth of bacterias that create vinegar and other nasty characteristics. I would need to fill the barrel to capacity and keep it filled as it evaporates. However, for a 59 gallon barrel, this means that I would be handling a 120 lb. barrel filled with 492 lbs. of wine–roughly 612 lbs. Obviously, this isn’t a practical size for what I intend to do. For comparison here’s a chart showing the different sizes of barrels:

Gallons Liters Weight (empty) Weight (full) Price Cost/Gallon
59 225 120 lbs. 612 lbs. €450 €7.63
30 114 93 lbs. 343 lbs. €280 €9.33
26 100 88 lbs. 305 lbs. €250 €9.62
13 50 66 lbs. 175 lbs. €200 €15.38

These are 2008 prices in Euros for Hungarian barrels without freight costs, so with the declining value of the dollar, I’m sure these are even more expensive now. I’m just using these prices for comparative purposes. Notice that the price per gallon is more than double to make 13 gallons versus 59 gallons which is why commercial wineries opt for the larger sizes. Another issue to consider with the smaller barrel is that for the volume of liquids, the surface area contacting the wine is greater. I haven’t been able to find any information online about the correlation between barrel sizes and time to achieve nearly the same results so I did my own rough estimates in this table:

Gallons Surface Area cm3/Gal. Time Ratio Example (days) Example (weeks)
59 19201 cm3 ~325 1.00 121 17
30 16529 cm3 ~551 0.59 72 10
26 10964 cm3 ~422 0.77 94 13
13 7477 cm3 ~575 0.57 69 10

To compute the surface area of a barrel, I used the formulas for surface area of a cylinder and averaged the tapering of the barrel staves.  The diameter of the cylinder assumes the diameter of the bilge or largest part of the barrel plus the head diameter divided by 2.

Surface Area = (π × ((DbDh) ÷ 2) × L) + (π × Dh × 2)

where Db is bilge diameter, Dh is head diameter and L is stave length

By looking at the surface area per gallon, you’ll notice that a smaller barrel will have a greater effect on the wine than a larger barrel given equal amounts of time because of the increased surface area by volume. In fact, the smaller barrel may over-oak the wine before realizing any benefits from evaporation. You may notice that the 30 gallon barrel has a greater surface area ratio than the 26 gallon and that’s because the 30 gallon has a more elongated shape. The above example shows the amount of time for the smaller barrel sizes based on 4 months (121 days or 17 weeks) of barrel aging in a 59 gallon barrel. To achieve a similar amount of oak, I would need to age for only 10 weeks in a 15 gallon barrel. Of course, the effects on the wine will probably not be quite the same since the rate of evaporation may not be equal. I’d be interested if anyone has any firsthand experience with smaller barrels.

More tomorrow…

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2 Responses leave one →
  1. Winemouse permalink
    October 13, 2014

    This post was a solid idea, but the execution is sloppy on two points:

    First, surface area will be measured in cm^2 (area), not cm^3 (volume).

    Second, the formula for the barrel surface area is incorrect. The “sides” are calculated correctly but there should be two “ends” at Pi*(Dh/2)^2 (formula for area of a circle), not the Pi*Dh that is listed (formula for circumference of a circle). So the total surface area formula should be:

    Pi*L*(Db+Dh/2) + 2 [Pi*(Dh/2)^2]

    Cheers!

  2. Blake Ragghianti permalink
    November 19, 2015

    I have this all worked out in a spreadsheet if you’re interested.

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