A few months back we had a brief discussion on the rate of decrease in
wine volume in barrels (ullage). At that time I decided to measure the
topping up of my two barrels. One is a 60 liter French Limousin barrel
containing a Cab Sauv/Merlot blend (Barrel #1) and the other is a 55
liter squat (burgundy styled) Hungarian barrel containing Chardonnay
(Barrel #2).

Days from Total Wine Average Daily
last filling Loss (mls) Loss (mls)

Barrel #1 12 375 31.3
Barrel #2 12 100 8.3

Barrel #1 9 100 11.1
Barrel #2 9 175 19.4

Barrel #1 21 375 17.9
Barrel #2 21 375 17.9

Barrel #1 13 150 11.5
Barrel #2 13 125 9.6

Barrel #1 17 150 8.8
Barrel #2 17 350 20.6

Barrel #1 11 125 11.4
Barrel #2 11 150 13.6

Barrel #1 20 250 12.5
Barrel #2 20 175 8.8


Since all measurements were taken on the same it is easy to directly
compare the loss and it was surprising that there is quite a variation
between the two barrels, in one case more than three times the volume.
Also, the fact that both barrels behaved quite inconsistently ie neither
required consistently more than the other. I will admit that my
readings were taken from estimates in the wine I used from top-up
bottles but I feel the accuracy was likely within 100 ml as I always use
bottles or half bottles to top up. The highest rate of loss (barrel #1,
first reading could have been an error) but there were also several
higher readings between 17.9 and 20.6 ml/day.

I know there are several factors that influence ullage apart from the
size, tightness of the barrel and other construction factors and
probably the type of oak. I expect these other factors are primarily
temperature and humidity and maybe even barometric pressure.

My primary learning is that I thought I was topping up more frequently
than I was especially since I was doing the test I probably topped up
even more frequently than usual. In the future I plan to record the
date of topping up so that I can monitor my frequency a little better,
expecially in the summer.

Any comments would be appreciated.

Cheers,

Glen Duff