Carboxymethylcellulose
CMC, cellulose gum
A durable tartrate stabiliser for whites and sparkling.
Typical dose
Per the product sheet, at bottling into a filtered white.
When to add it
At bottling; whites and sparkling only.
In practice
Inhibits tartrate crystal growth for the life of the wine, unlike metatartaric acid, and cheaply. It reacts with the colloids and colour of red wine to form its own haze, though, so it is a white-and-sparkling tool; reds are stabilised another way. The wine must be protein-stable first.
Linked faults are the ones this addition either treats or, used wrongly, causes. The fault page says which, and whether it can be undone.
Others in tartrate and colloidal stabilisers
Metatartaric acid
A cheap, temporary block on tartrate crystallisation.
Mannoproteins
Yeast-derived colloids that steady tartrate and protein and add texture.
Potassium polyaspartate
A newer tartrate stabiliser that also works in red wine.
Bitartrate seeding
Seeds cold stabilisation so tartrate drops faster and more completely.