I've had two demijohns of blackberry wine fermeting for about 3 weeks. One of them was slightly over filled and frothed through the airlock, leaving winey yeasty liquid in the airlock.
Rather than remove and clean the airlock, my approach was to drop a bit of sanitiser into the liquid and leave it be.
Have I done a good thing or is there increased risk of contamination?
It depends on how strong the sanitizer was. You diluted it when you added it to the "frothed" airlock. I would have made it up a little stronger than normal maybe 2X stronger.
I think though its better to sanitize a piece of aluminum foil, spray the airlock and neck of the demijohn with sanitizer (or wipe with a soaked clean towel with sanitizer), pull off the airlock and cover it with the foil. Then go clean and sanitize the airlock and replace it.
In general though when this stuff happens the fermenter is pushing enough CO2 out of the vessel that stuff doesn't get back in there too much. As long as the issue is address while the ferment is active the worries are much reduced.
