Kieselsol
silica sol, silicon dioxide
A negatively charged fining, paired with gelatin for a compact lees.
Typical dose
Per the product sheet, dosed together with a protein fining such as gelatin.
When to add it
With gelatin or isinglass, as a two-part fining.
Legal limit
No specific limit that this reference states. Additions are still governed by the treating-materials rules where you make wine, so check them.
Vegan
Yes. Nothing animal-derived, so a wine fined with it can still be labelled vegan.
In practice
Carries the opposite charge to the protein finings, so a gelatin-and-kieselsol pair pull each other down into a tight, compact lees that loses less wine than either alone. It is half of a system rather than a fining used by itself, and it is vegan.
Others in fining and clarification
Bentonite
Adsorbs unstable protein to prevent haze in whites and roses.
Isinglass
Fish-derived collagen that polishes whites to brilliance at a tiny dose.
Gelatin
Collagen that strips harsh tannin and astringency from reds.
Egg white
The traditional, gentle softener of barrel-aged red tannin.
Casein
Treats browning and light oxidation or taint in whites.
PVPP
A synthetic that removes browning, pinking and bitter phenols.
Sparkolloid
A polysaccharide clarifier for stubborn hazes that resist other finings.
Activated carbon
A blunt last resort that strips colour and off-odours together.
Plant protein fining
A vegan substitute for gelatin and isinglass.
Diatomaceous earth
A filter aid, rather than a fining, for wines too cloudy to filter.