Number

062-EN

Section

General Section

Use

Abstract

Volatile binders are used in conservation and archaeology as hydrophobic protective coatings for fragile objects during excavation, transport or handling. Cyclododecane and camphor are two examples of binders that can be readily replaced by tricyclene or menthol. There are however limitations to this substitution which are important to bear in mind, tricyclene is for example shorter lasting than cyclododecan.

Substituted substances

Alternative Substances

Reliability of information

Evidence of assessment: there is evidence of an official (positive) assessment of the substitution
Internet information: data are from an internet document and only a basic and partial evaluation could be performed

Reason substitution

other reasons

Hazard Assessment

Substance to be substituted: Camphene is of high concern, according to OSPAR - section B. Cyclododecane is not included in the database of hazardous substances according to SUBSPORTplus Screening Criteria (SDSC) and has no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Alternative substance: The alternatives are not included in the database of hazardous substances according to SUBSPORTplus Screening Criteria (SDSC) and have no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). » Check the Substance Database according to SUBSPORTplus Screening Criteria (SDSC)

Description of Substitution

Volatile binders are used in conservation and archaeology as hydrophobic protective coatings for fragile objects during excavation, transport or handling. The binder is applied in molten form to the surface where it quickly evaporates leaving a surface that protects the objects for several weeks depending on the thickness of the coating. This technique can be used to stabilise and preserve several different objects including wall paintings, sculptures and stained glass. It can also be used to fix loose paint layers and protect water-sensitive parts of objects (paper, textiles, etc.). The main differences between the four different compounds are differences in vapourisation and in hydrophobicity. Cyclododecane and menthol have a comparatively low vapourisation rate making them suitable for long conservations while tricyclene and camphor have a higher vapourisation rate, which means that they dry up quicker when applied to the object but also expire quicker. Menthol also differs from the other compounds in that it is polar in nature which means that it is only slightly hydrophobic and therefore not as effective as a water barrier as the other compounds. It is, however, a better adhesive. It important to bear in mind that all volatile binders have to be as pure as possible. Impurities tend to stick to the object even after the binder itself has evaporated. As stated in the case description, the advantages and disadvantages depend on the purpose of conservation. Is it only for a short term or a long term? Is there relevant exposure to water? These are some of the factors that decide which compound to use. An advantage of substituting camphene is that it must be used together with a stabilising additive since it is sensitive to oxidation.

Case/substitution evaluation

According to the provider an important advantage of the alternatives is their lower volatility. It must be noted that the alternatives are not suitable for all applications, which is described in the document. Even though the alternatives are less volatile and also less persistent, they should be handled with care to avoid exposure of the user or disposal into aquatic environment.

Type of publication and availability

Freely available

Publication source

Type of publication and availability

http://cool.conservation-us.org/byform/mailing-lists/cdl/1999/0218.html

Date, reviewed

December 11, 2020