Those of us who brew big beers and pitch a lot of yeast know all about blow off. That wonderful frothy head that grows way beyond the confines of the carboy and blows through the bubbler and gets all over the place.
The remedy you say is simple, use a blow off tube: a large plastic tube, one end of which fits and seals directly into the top of the carboy while the other end is put in a jar with some sanitized water in the bottom. This will let all that extra foam and CO2 be released from the carboy and avoids the mess.
The Yeast Recovery System is simple, just make sure that all parts, the blow off tube, the jar, the water in the jar, and the foil to cover and partially seal the tube into the jar are all sanitized when you put it together. All of the foam blow off collected in the jar is pure useable yeast and can be used to start another batch or to help ferment out the batch that it was blown from. After the ferment stops blowing off, take the jar, cover it completely and place in the refrigerator to allow it to settle. After a few days it should have clear liquid on top that can be poured off and the remaining slurry can be put in a sanitized container and kept refrigerated until needed.
This System has worked great many times, especially when used to aid in fermenting out those last few specific gravity points to make that brew just right. tpb