Gels Cleaning Research

New research addressing questions on the use of solvent-based gels on painted surfaces

Project Details

One person watches while another person holds a vial inside a science lab

About

Goal

In the mid-1980s, solvent-based gels, resin soaps, and enzymes were introduced as alternative cleaning systems for painted surfaces. By the late 1990s persistent concerns remained regarding the use of gels cleaning systems—in particular, the question of residue from these systems. If there was a residue, did it pose a future risk to the surface of the painting or object? The Gels Cleaning Research project sought to carry out in-depth research in an attempt to settle the "residue question."

Outcomes

  • Two parallel studies were carried out to evaluate the deterioration products of representative surfactants used in surface cleaning: (A) the aging of surfactants on a polytetra-fluoroethylene film and (B) the aging of surfactants on a linseed- oil film. The results will help conservators in selecting the surfactant for a gel formulation.
  • A study indicating that surfactant residues on painted surfaces exist initially in low concentrations and decrease within a relatively short period of time. This information may reduce some of the concerns that conservators have regarding possible long-term effects of surfactant residues.
  • A cleaning experiment in 1999 in which ten commonly used organic solvents and solvent mixtures were applied to samples from the same painting used for the gel residue tests. The results were compared with those of the cleaning experiment on painting samples to determine the difference in the quantity of residue left by each cleaning method.
  • The paper "Surface cleaning: Quantitative study of gel residue on cleaned paint surfaces" published in the preprints and program of "Tradition and Innovation: Advances in Conservation," the 2000 biennial conference of the International Institute for Conservation of Artistic and Historic Works (IIC), in Melbourne.
  • The paper "Detection of residues on the surfaces of objects previously treated with aqueous gels" published in the preprints and presented at the 13th triennial meeting of the ICOM-Committee for Conservation held in Rio de Janeiro in September 2002
  • The paper "Scientific investigation of surface cleaning processes: Quantitative study of gel residue on porous and topographically complex surfaces" published in the preprints and presented at the 13th triennial meeting of ICOM-CC
  • Publication of Solvent Gels for the Cleaning of Works of Art: the Residue Question
  • An initial methodology—a logic tree and test kit of cleaning materials—to help conservators design gel formulations for specific cleaning problems
  • Development of a database software system based on field testing of the initial logic tree

Background

Cleaning of painted surfaces has been carried out mainly with organic solvents or alkaline-based aqueous cleaning solutions—or by mechanical means, such as scalpels. The former offers minimal control over the cleaning process, which often involves selective removal of a layer or layers of grime, varnish, or paint; however, many of the solvents employed are quite toxic. Mechanical removal is extremely time-consuming and often presents considerable risk to the underlying layers.

Conservators also have had the option of using wax-solvent paste mixtures. The high viscosity of these mixtures provides more control over the cleaning process, particularly for three-dimensional objects such as sculptures. The workability of these mixtures, however, limits their effectiveness in many cleaning situations. Cleaning grime or other layers from unpainted surfaces in general also presents problems such as color change to the surface and absorption of the cleaning agent into porous surfaces.

Project History

Partners

Winterthur Museum, Garden and Library; Department of Art Conservation, University of Delaware; Department of Chemistry, California State University, Northridge

Resources