Isinglass as a Sustainable Material: Research

Author: Daniela Molinari

For my master’s degree dissertation at Northumbria University, I wrote about the environmental impact of one of conservation’s most prized materials: isinglass. The following paragraphs provide an overview of the research that I did from 2018-2019.

Isinglass is one of the materials used most frequently in various conservation disciplines. It is an adhesive made from the swim bladder of the sturgeon fish, which is usually mixed with a small amount of water and heated to form the desired substance. In easel painting conservation, isinglass is used quite often to treat paint layers. Isinglass has good working and handling properties and a low gel point. It is compatible with other adhesives such as wheat starch paste, it swells in water, and it is moderately reversible (Heiber, 2003). Its ease of use and functional versatility make it difficult to replace.

Sturgeon are an ancient species of fish that have existed since the late Triassic period, more

than 200 million years ago. They are native to the rivers, lakes, and coastlines of most of Eurasia and North America, so they occupy a large range of global waterways (Reinartz, Slavcheva, 2016; WWF, 2019b). Sturgeon, among many other creatures, are declining rapidly in numbers due to human impact. It is therefore important that the materials and facilities used for the production of isinglass be re-purposed to facilitate the discovery or creation of a more sustainable product. This can be achieved through work similar to the research and testing that is being carried out on bio- and bio-based adhesives. One alternative to isinglass that was considered in this research was a soy-protein adhesive. Alternative adhesives such as those derived from soy tend to have low water resistance and good adhesive qualities, but their extraction and production are potentially devastating to the environment. Thus, this research was complicated by the environmental impact of possible alternatives, in addition to the lack of literary resources that have been found relating directly to painting conservation.

A survey about conservation’s environmental impact suggested that conservators do care

about sustainability, as most respondents were open to adopting more sustainable practices. Therefore, conservation professionals should be encouraged to question the sustainability of materials in order to expedite further research and the development of truly sustainable alternatives.

It is now clear that the two biggest causes of the decline of the sturgeon fish are pollution and over exploitation. My research, which was carried out through surveys, interviews, and

literature reviews, has established that the small amount of isinglass used by conservators is

unlikely to have a significant impact on the environment. However, the unsustainable ways in

which sturgeon are being harvested for caviar production and consumption have greatly impacted the quality and availability of isinglass for practicing conservators. Patterns of

unsustainable practice are cyclic, and no industry is exempt from their repercussions or the

responsibility of preventing them. A basic goal of sustainable practice is to find the course of

action that is best for future generations, and this research has found that isinglass is

moderately unsustainable for future generations of conservators. Though environmental

conservation and the conservation of cultural heritage are separated by a seemingly vast divide of understanding, they are inseparably entangled in regard to issues like renewable resources.

My research shows that although there are problems related to the environmental impact of

isinglass, there are reasons to hope that solutions might be found. For example, the extensive current research on bio-based adhesives may inspire similar studies in conservation, and policies that encourage the rejuvenation of sturgeon populations over time are being developed. The sustainability of isinglass is one element of a much wider debate on the conservation of the planet.

Conservators should understand where their isinglass is sourced, because wild sturgeon provide the highest quality material. When working with isinglass from farmed sturgeon, the ethical policies and sustainable practices of various farms can be determined through research. Awareness of the ecological, commercial, and cultural values associated with each material that is used in conservation must be encouraged through campaigns and research, and through a global understanding of the impact of sustainable products in general (Reinartz, Slavcheva, 2016). The reintroduction of a species into its natural environment takes time, especially in the case of the sturgeon, which matures slowly. If sturgeon continue to decline in numbers, conservators must find an alternative to isinglass that is equally versatile and useful. It is also vitally important to raise public awareness of the fact that repercussions of environmental damage can trickle down into industries such as conservation. The inclusion of sustainability issues in the conservation education system would also be ideal, as many survey respondents did not know that isinglass is becoming more scarce. Finally, it is recommended that conservators become involved in sturgeon rehabilitation efforts. Support can be provided either monetarily or through individual or institutional dissemination of information on the issues faced by the vulnerable sturgeon.


Freundlich, H., Gordon, P.S. (1936) ‘The swelling pressure of isinglass in water and aqueous

solutions’, in Transactions of the Faraday Society, 32, pp. 1415-1424.

Heiber, W. (2003) ‘The Thread-by-Thread Tear Mending Method’ in Bustin, M., and Caley, T.

(Eds.) Alternatives to Lining: The structural treatment of paintings on canvas without lining.

London: United Kingdom Institute for Conservation, pp. 35-47.

Reinartz, R., Slavcheva, P. (2016) ‘Saving sturgeons: a global report on their status and

suggested conservation strategies’. Available at: (Accessed: July 1, 2019).

Schellman, N.C. (2007) ‘Animal glues: a review of their key properties relevant to conservation’, in Studies in Conservation: The journal of the International Institute for Conservation of Historic and Artistic Works, 52(1), pp. 55-66.

World Wide Fund for Nature (2019b) Sturgeon. Available at: (accessed June 6, 2019).