A previous post has already introduced the subject of a most useful work that was published in the 1930s – Parsons’ Decorative Finishes. Subsequently I have used it as a ‘prompt’ for posts dealing with Imitation Stone Paints, Flat Finishes; Gloss Enamel Finishes and several other types of paint.
The book is divided into 17 sections and one of these (Section Eleven) will be considered in this post which looks at the metallic paints offered by Thomas Parsons’ at the time. When compared with most modern ranges one can see that a wide range of colours was on offer.
Sometimes confused by the uninitiated with gilding, metallic paints produce a very different effect. If examined closely the painted surface will be seen to be made up of countless tiny flakes of metal, rather than a thin sheet.
Metallic paints, in one form or another, have been employed in this country for over three hundred years. In its simplest form – the dusting of a varnish-sticky surface with metallic powder before covering with a protective coat of varnish – the earliest reference that I have found is of 1685:
“First wet your work with Varnish, with a soft brush, then while ’tis wet dust your speckles upon it thro’ a piece of Tiffany,1 and then varnish it twice, to keep ‘em from rubbing off, ’tis enough.”2
The same process was described some two hundred years later:
“A gold paint, patented by H. Bessemer, is now much used, which, by the highly improved manufacture of bronze powder, has greatly reduced its price in England, although very much is still purchased from the German dealers. As an impalpable metallic powder, its application to plaster, wood &c., is effected by using a camel’s hair brush, which is dipped into a little of the powder and rubbed up in a small portion of transparent gummy varnish, by which it adheres to the surface. For all outdoor works it requires to be varnished over for better preservation”.3
Whilst dusting with metallic powders is still referred to in the technical literature of the early twentieth century, the two main methods of applying a metallic coating to a surface involved the use of a paint.
The preferred approach was the mixing of aluminium powder or bronze powder with a quick-drying varnish medium of low acid value, rather than the use of a ready-mixed metallic paint as this tended to lose its lustre when stored for long periods.
Silver metallic paints are never produced using that metal, but with aluminium. A grade is employed that has been specially treated to induce the leaf-like particles to lie flat in the surface of the applied paint. This accounts for the great opacity and brilliance of the finish. At the same time, this alignment of the particles presents something approaching a thin barrier of aluminium against the ingress of moisture and other destructive agents. For this reason an aluminium wood primer is frequently employed on resinous woods and over creosoted or bitumen-painted surfaces to prevent bleed-through. At the same time, this thin barrier coat was often recommended for use on ironwork to resist corrosion. Aluminium paint can also be used as a finish where a high degree of reflectivity of light is required.
Bronze powders, made from alloys of copper, tin and zinc vary in colour from pale lemon gold to deep copper bronze and are employed to produce gold effects. The colour range produced by Thomas Parsons’ in the 1930s was certainly quite extensive.5
Being heat resisting, metallic powders, were often used for heating-pipes and radiators, although it is not generally realised that they actually reduce the radiation of heat to a marked extent. A radiator finished in aluminium paint will emit rather less heat than one treated with a pigmented or non-metallic paint. They are also liable to discolouration if exposed to acid, alkali or sulphurous fumes. Frequently they were over-glazed to produce decorative effects and sometimes they were varnished for protection. (An earlier post on scumble glazes mentioned the use of metallic paint as a base for glazing.) It has always been sound practice to apply a buffer coat of thin shellac4 lacquer before glaze or varnish in order to insulate them from the oxidising effects of the oil in the superimposed material.
Thomas Parsons very sensibly recommended the application of a white or grey undercoat before using the aluminium metallic paint and a buff one underneath the bronze ones.
1 Tiffany – Light weight silk or linen cloth which was almost see through. Usually used to cover embroidery to protect it and for veils. It could be white or black and made in fancy weaves. It was used for neckwear and for the lining of slashed garments (the puffs). My thanks to the Renaissance Tailor for this explanation.
2 Anon. A short introduction to the art of painting and varnishing. 1685. p.14. Although bound with works by John Smith, the author of The Art of Painting, of 1676, and thought by the British Library cataloguer to be by him, it is in a coarser and more obscure type of writing – see J. R. Mulryne and Margaret Shewring (eds.). Shakespeare’s Globe Rebuilt. Cambridge University Press. 1997. p.145.
3 Joseph Gwilt. An Encyclopaedia of Architecture, Historical, Theoretical, & Practical. 1899. p.698, para. 2277b.
4 Shellac is a spirit soluble resin which is formed from the secretion of insect parasites which attach themselves to the branches of trees, the twigs eventually becoming encrusted with the substance. The chief source of supply is India. The best quality is known as orange shellac, cheaper grades being called button shellac or garnet shellac. White shellac is made by bleaching the resin with alkali.
Shellac forms the basis of French polish and of many kinds of spirit varnish. When dissolved in methylated spirits it is used by the painter as knotting, to prevent the resin from the knots in timber from bleeding into a paint film; it is also used as a sealer to prevent various other substances from bleeding.
5 The ‘bobbly’ appearance of the Parsons’ colour card has nothing to do with the paint – it is merely the paper used.
A number of different colours in metallic paints are available from Papers and Paints.
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