Gelatin
Collagen that strips harsh tannin and astringency from reds.
Typical dose
Bench-trial, roughly 30 to 100 mg/L, usually paired with a silica sol.
When to add it
On a tannic finished red.
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
No. Animal-derived, and usually an allergen to declare, so it rules out a vegan label and needs care on the ingredients list.
In practice
Binds and drops the hard tannins that make a young red astringent, softening it quickly. It overfines easily, stripping colour and body, so it is trialled and usually paired with kieselsol, which gives it something to settle against and tightens the lees. It is an animal product.
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.
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.
Kieselsol
A negatively charged fining, paired with gelatin for a compact lees.
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.