I've been following Jack Keller's recipe for Rhubarb wine. The basic procedure is: Mash rhubarb, put in straining bag in primary. Pour on water, set 3 days stirring each day. Strain juice back into primary. Add precipitated chalk. Wait a few hours. Add other ingredients including yeast. Leave over night. Transfer into secondary.
That is the point I have got to. When I strained the juice, it was just juice. After adding the chalk and subsequently sugar, yeast, nutrients and lemon juice, it's a different story. A brain-like cap formed in the primary over night. When I came to transfer to secondary I thought "If I throw it away no doubt I'll be throwing away lots of active stuff." So I stirred it back in and transferred.
Now in the secondary, after a few stirrings, the cap has broken down and fallen to the bottom where there is now 2 or 3 inches I think of these heavy flakes. I never got this sort of substance when I have started other fruit wines and certainly not this quantity.
Is it the chalk binding with the other ingredients that caused these solids?
Keller doesn't say of course "You'll think your wine has giant dandruff." I'm sure he's guessing I've seen similar before but I haven't :)
Here's an image of the scale of settling I have after just 48 hours: