Do we need a new method for describing and analysing coatings with special effect pigments? A discussion and suggestions based on case studies.

Elke Cwiertnia

Effect pigments are used in many modern design objects and everyday products and increasingly can also be found in artworks and modern cultural heritage objects. However, their variety and complex technology is often not known to curators or conservators, who have to describe, conserve or recreate specific effects.
Effect pigments can be divided in two subgroups: metal effect pigments and special effect pigments. The group of special effect pigments contains several specific subdivisions that are defined by visual effects or other characteristics such as non-visible energy changes.
The aim of the research was to compile an overview about the available modern special effect pigments, their technology and use, with a focus on pearlescent pigments and visual effects – such as colour travel and shift – in coatings.
The final effect created with these special pigments is – much more than for absorption-based pigments – an interplay between pigment, its location in the paint system, binding media, underground and application technique. Each of these parameters plays a crucial role and is especially important to consider during retouching. They will be explained using reconstructions and case studies.
The analysis of the paint system is the basis for a successful visual integration of a lacuna, starting with the type of pigment, explaining its position in the paint layer and in relation to other pigments, fillers and coloured layers in the system. A methodology to describe, compare and distinguish special effect pigments was developed based on visual examination and analysis using different microscopes as well as colour and gloss measurements. This is demonstrated on case studies from the collection of the Deutsches Museum in Munich.
In addition to these available methods in the conservation science department at the Deutsches Museum Munich, standard methods used in the paint industry are shortly discussed and both conservation science and coatings industries’ methodologies compared in regard to approach, applicability and quality of the gained results.
This research provides tools that will help conservators and curators describing and conserving surfaces with effect pigments on modern and contemporary art, design and cultural heritage. It raises questions regarding the demand for new methodologies for an ever increasing range of new materials which do not fit into old moulds.