Exposure to air

[Frjen]

When measuring sg, I need to screw the lid/airlock off which exposes tge wine to air.

Is it harmful to the wine ?

 

[Johnd]

When measuring sg, I need to screw the lid/airlock off which exposes tge wine to air.

Is it harmful to the wine ?

Exposure to air in a properly topped up carboy is minimal and nothing to worry about. We all have to crack our carboys open on occasion for tasting, rackings, additions, testing, etc., no big deal unless you're digging in it every day and leaving it open for a long time or forget to replace the bung / airlock.

 

[whackfol]

Since there is little reason to check sg after the wine finishes fermentation, you have the added advantage of some CO2 protecting the wine.

 

[Frjen]

The wine is still fermenting, so I need to keep an eye on it and measure "SG" or is it called something else while it's fermenting ?

 

[NorCal]

While it is fermenting it is producing co2, which will protect the wine. It is when it nears the end of primary fermentation that's you need to be mindful of o2 exposure. I am of the opinion that the exposure once a month for testing and topping and every 4 months for racking is not significant enough to to be damaging to the wine.