Silver leaf and its pitfalls
Silver leaf is used both in poliment silvering and for silvering with Mixtion and gilding size. Silver leaf is made from pure silver and is only suitable for silvering for indoor installation. Immediately after application, the silver leaf must be given a coat of lacquer, as otherwise it will begin to oxidise in the air.
Special characteristics when working with silver leaf
- Silver leaf should only be applied in a workshop or in an environment with low air humidity, as the material oxidises very quickly.
- In workshops in which work is performed using acids and where solvent fumes must be taken into account, leaf-silvering should not be carried out and silver leaf in booklet format should not be stored.
- Silver leaf must not be held in the hands, so as to avoid subsequent oxidation stains.
- When silvering using a gilder’s tip, the tool must not be greased using Vaseline as the grease residues prevent the desired even oxidation.
- If the gilder’s tip is wiped down with a cloth that has been dampened with kerosene, then the silver leaf can be applied without any problem. Kerosene evaporates without residue, and neither does it leave residue on the silver leaf.
Lacquer for silver leaf and the associated problems
All silvering must be treated by a coat of lacquer in order to protect against oxidisation. If working on small surfaces and picture frames, shellac and cellulose lacquer are recommended. Wall surfaces and larger furniture pose a number of challenges.
The majority of lacquers are unfortunately not suitable for silver leaf. We have summarised the most frequent problems when using lacquer with silver leaf and the corresponding causes:
- The silver leaf oxidises underneath the lacquer.
- The lacquer discolours and turns brown.
- The dried coat of lacquer comes away from the silver leaf surface like a film.
In all instances, these problems cause irreparable damage, which requires the entire job to be repeated. There are many reasons as to why these problems occur, and these cannot always be predicted.
- When silver leaf oxidises, this can be as a result of the substrate. An unsealed or insufficiently dried substrate structure are frequent triggers of this problem. Unsuitable lacquers and lacquers applied too thickly are also possible causes of this type of problem.
- If the lacquer turns brown, this is generally the result of a lack of UV components in the lacquer. Other causes could be that the lacquer is incompatible with the adhesive used or with the silver.
- If the coat of lacquer comes away from the silver leaf surface, then it was simply the incorrect lacquer, as only a select few lacquers are suitable for use with silver leaf. At present we can recommend acrylic parquet lacquer, subject to certain conditions. Because lacquer manufacturers are continually making product optimisations, each newly purchased container of lacquer must be tested prior to use on silver.
Intermediate primer as a means of preventing oxidisation
The problems of oxidisation and the coat of lacquer coming away from silvered surfaces can generally be resolved with an intermediate primer. To this end, a thin coat of warm, liquid rabbit-skin glue or gelatine solution is applied to the silver leaf surface. Once the coat of glue has dried, the first layer of lacquer can be sprayed on in a thin layer. After a further drying time, a further coat of lacquer is applied. The rabbit-skin glue serves as both a separating and an adhesive layer, which prevents the oxidisation of the silver and the coming away of subsequent coats of lacquer.
Important: tests must be conducted prior to silvering a large area.