It sounds like you took the right approach. A VA (volatile acidity) of 0.70 is not “out of this world” high, though it is a little elevated. Especially if this was a wine over a year old, a VA like this wouldn’t necessarily alarm me unless it made a big jump (say from 0.50 to 0.70) within a month or less. That would be a sign of some kind of microbial bloom. If your wine has just had a gradual increase or “creep” in VA over the months, that is totally normal and I would not hesitate to use the barrel again. The treatment you describe above is pretty industry standard.
However, if you experienced a big jump in VA in a short period of time, I might hesitate to use the barrel again, especially if you’ve used it many times and had extracted all of the oak flavor and aroma out of it (2-3 years, depending on the barrel). If it’s a brand new barrel and has only been used once I might take the risk and re-use it after cleaning it out well as you describe above. In that case, I would make sure to monitor the VA of the new lot every 2-3 weeks for about three months to make sure I didn’t have anything growing that I didn’t want. After that, I would say you could back off to monthly monitoring. Good luck!
