Dark specks??

[Jaybrew226]

I'm hope someone knows what this is. My buddy finished brewing and after racking the finished beer started to soak his glass carboy with PBW. After an overnight soak he scrubbed the carboy and found these dark specks that were hard to the touch. They could be scrapped off with the fingernail but the carboy brush wouldn't touch them. Any idea what these deposits are? I guess they were not there prior to soaking.

 

[mattd2]

Maybe beer stone form during the PBW (alkaline) wash? Here are some articles for further reading:
http://www.micromatic.com/beer-questions/what-is-beerstone-aid-158.html photo of beer stone in draght lines
http://www.birkocorp.com/brewery/wh...stone-a-look-at-alternative-cleaning-methods/ chemical company overview of beerstone
http://hbd.org/discus/messages/43688/45774.html?1220310202 another homebrewer that might have had an issue similar to yours

 

[IslandLizard]

That looks like a hand! Or Mother Teresa.

Oh, you mean the tiny granules? Undissolved PBW perhaps?

 

[brewinginnc]

Wilson