Can this scum be mold or something else? PHOTO POSTED NOW.

[Gilligan]

Today, I noticed deposits of a scum-like pure white substance in an irregular ring around the circumference of the cider level in my glass carboy. The ring ranges from a tiny white line to about 2mm high. It looks just like white soap scum, and it is present only where the liquid meets the wall of the carboy, there's absolutely no sign of it on top of the cider, only on the glass. It wasn't there last week and the seal on the carboy is good and hasn't dried out.

I'm somewhat hopeful because it doesn't look like any of the moldy carboy photos I've seen on the web. The scum isn't fuzzy and there isn't any of it on top of the cider. It is limited to the line where the top of the liquid meets the glass.

Does anyone know what this is? Is there a mold that grows only on glass and not on top of the liquid?

Some data about the contents:

Apple juice
Golden raisins boiled in water before adding to the juice, about 10 ounces
Red Star champagne yeast
About 4 months in the primary fermentation carboy, never transferred out of primary
Still a little cloudy, but it stopped clearing over a month ago, so this is as clear as it will get, I assume due to the raisins

 

[Bilsch]

Why would you leave anything in the fermenter for 4 months?

 

[Gilligan]

All the specs are dust and glare on the outside of the glass. There's nothing on top of the cider. The edges of the white deposits are smooth, not fuzzy.

 

[RolandD]

Looks like dried foam. It's normal, but usually there's much more. I'm curious, too. Why four months in primary? I transfer my ciders to secondary after two weeks, then keg after two weeks more.

 

[Gilligan]

Roland, I keep it there until it clears. I found no difference in flavor quality between this process and transferring to a secondary to clear.