Monitoring and Documentation of Colour for Conservation

Module Synopsis

This workshop addresses the requirements for measuring the colour and appearance of surfaces and for monitoring colour change. Factors contributing to surface colour are covered, as well as methods to evaluate changes and determine if they are significant. Methods to define suitable test methods for many substrates and conditions, determine the reproducibility of the measurement, and set tolerances for visual change are also included.

Learning Outcomes

Upon completion of this module, participants will be able to understand the following basic principles:

• physics of light and colour
• basics of human colour vision
• colour and other appearance-modifying phenomena
• visual evaluation versus instrumental evaluation
• light sources and their effect on the visual appearance of surfaces
• numerical colour appearance systems
• colour communication and interpreting colour differences or changes
• colour measurement instruments and basic measurement principles
• selection and operation of suitable colour measurement devices
• standard test methods for colour and appearance
• experimental design and systematic test protocols
• colour change evaluation
• tolerances for colour matching or visual colour change
• colour stability
• accelerated light ageing tests (including micro-fade testing)

Units

Introduction
Factors that contribute to surface colour and appearance, methods to evaluate colour and appearance, when to use colour measurement.

Basic Principles
Physics of light and colour, basics of human colour vision, colour vision testing and defective colour vision, colour and appearance, standard illuminants, viewing geometries.

Colour Identification
Human colour memory, colour name standards, quantification of colour, evolution of colour appearance systems, colour communication, and colour differences.

Colour Communication
Colour measurement instruments and basic measurement principles, colour coordinates, instrument geometries, light sources and perceived colour, colour rendering index, metamerism.

Operation of Measurement Devices
Calibration and standardization methods, equipment maintenance, instrumental stability, determination of experimental error, defining reasonable tolerances for colour change.

Experimental Design and Measurement Device Selection
Selection of instrument for measurement, defining test protocols, use of templates for reproducible positioning or alternative methods, protection of artifact surface during colour measurement, use of standards and control samples, data handling (software, spreadsheets, graphs), interpreting colour coordinates and colour change, use of indices, reporting of results, case study examples, use of a standard light booth.

Colour Stability
Test standards for artists' materials, blue wool test cards, accelerated ageing tests (including micro-fade testing), and reciprocity.

Other Optical Properties and Test Methods
Gloss, sheen, haze, opacity.

Target Audience

Conservators, conservation scientists, and other personnel responsible for the preservation of museum collections.

Facilitator(s)

Nancy Binnie

Language

English (written materials available in both official languages)

Enrollment Limits

Minimum 10; maximum 20

Duration

2 days

Special Requirements

• Meeting room
• Projector
• DVD player
• Screen
• Computers with spreadsheet software