Dan,

You are certainly putting your wine in the barrel at risk. I would
stopping using this wine as top up immediately. I've seen this same
faint white ring in insufficiently topped up containers in my own
cellar. Some of the folks on this newsgroup helped me diagnose this as
mycoderma , a film yeast similar to flor yeast used in sherry
production. It definitely has tolerance to SO2 when given enough air
space and it will ruin your wine if permitted to grow.

Instead of allowing a partially filled bottle to sit for weeks, I'd
suggest splitting it into smaller bottles like 375mL bottles( or 187mL)
that you fill completely. I've even heard of people putting small
top-up quantitites into small plastic water bottles like Dasani or
Aquafina for very short periods of time (a week or so). The plastic is
soft enough to squeeze out air then cap tightly. If you must have some
air space in the container I would suggest sparging with inert gas.
You can get a canister of 'wine preserver' for about $10. It will
last quite a while.

If the affected quantity of top up wine is small, I would throw it out.
Otherwise, I'll pass along advice I got from Tom S. Spritz the 'white
ring' with sulfite solution, top up - all the way up - and cap tightly.
Make sure your barrel stays suffienctly sulfited and topped up also.
Now that this has been introduce to your barrel you can't allow it to
thrive.

One last thought, under normal circumstances, unless your barrel is
brand new, toping up every 2-3 weeks is probably fine.

Good luck,
RD



wrote:
> I've got a 50 litre barrel that I have a Cabernet in. I put a second
> run wine through the barrel before putting in the cabernet so I could
> get the initial oak out. Now I have my cabernet in it and it is doing
> fine. MLF is over, the wine is sulfited. I have to add around 50 ml
> of wine every week to top up. I am using bottles of raw cabernet that
> I keep in screwtop bottles. This wine is pretty heavily sulfited so
> slow oxidation but there is alot of head space in the bottle. I use
> this bottled wine for top up for 6 weeks or so.
>
> I've noticed a faint white ring in the bottle at the top of the wine.
> It smells fine. Am I endangering the wine by keeping my top up this
> way? I can't open a finished bottled wine every week for top up, I
> don't have enough. Can I keep this heavily sulfited wine around for
> that long without harm? How do you manage the top up for small
> barrels? If I had a larger barrel and was adding a bottle a week, that
> would be fine, but I'm using just small amounts. How do I manage this?
>
> Thanks in advance
>
> Dan