This is what you get when you overfill your brewing/fermenting vessel. There was less than 2" to the lid and as soon as things kicked off they burst through the small area left open when we sliglty unscrew the barrel lid to make an airlock. If you use normal airlocks the result will be the same...so much yeast foam it will fill the airspace and leave by any available means! I had to take the lid off, clean and sterilise it and so the same with the barrel threads.
I had a similar problem this year but in my case I believe it had more to do with the unusually warm autumn we had here in West Australia which kicked the fermentation process along faster than normal. Apart from cleaning off the gunk on the outside I just left it. I was more interested in keeping oxygen out of the main mix.
Bern67001 1 month ago