# Isinglass

**Ichthyocolla*, fish glue*

Kind: Animal

## What was it used for?

Broths and jellies; court plaster, isinglass brushed on silk with tincture of benzoin; and to clear wine and beer.

## What does modern science say?

Still used to clarify beer and wine.

## Pharmacognosy and toxicology

- **collagen**: from the swim bladder; now mostly of tropical fish
- **gelatin**: isinglass is a pure commercial form of it

**Mechanism.** Mostly collagen with few cross-links, so it dissolves readily; it clears drinks by aggregating the yeast and other particles, and stops working once heat above 29 C has denatured it. It is widely used in British brewing, above all for cask-conditioned beer, where it flocculates the yeast into a mass that settles, though many cask ales are not fined with it.

**Dose.** A food; a fish product, but wines fined with it, even at more than commercial doses, have proved a very low allergic risk to people allergic to fish.

**Standing.** A food-processing aid, permanently exempt from allergen labelling in the European Union under Directive 2007/68/EC.

## What lore surrounds it?

Its name is an English corruption of the Dutch *huisenblas*, sturgeon’s bladder.

## What did the older authorities say?

**Dioscorides.** Gives *ichthyocolla*, fish glue, made from the intestines of a “whale fish,” the best from Pontus, for head plasters, medicines for leprosy, and medicines to smooth the skin of the face.

## Sources

- Dioscorides, *De materia medica*.
- Pomet, P. (1694). *Histoire générale des drogues* (English, *A Compleat History of Druggs*, 1712).
- Wikipedia, “Isinglass.”
- *Encyclop dia Britannica* (1911), 11th ed., “Isinglass,” vol. 14, p. 872. Wikisource.
- Pe as, E., et al. (2015). Allergenic proteins in enology: a review on technological applications and safety aspects. *Molecules* 20: 13144–13164.
- Hickman, D., et al. (2000). “Isinglass/collagen: denaturation and functionality.” *Journal of Biotechnology* 79.

---

*Isinglass.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-03. The Thinking Press. https://thethinkingpress.org/materia-medica/isinglass

Historical description, not medical advice.