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Seeing in Different Ways: A Liz Magor Backpack Project
Seeing in Different Ways:
A Liz Magor Backpack Project

Why Paper Discolours (Part 2)
Why Paper Discolours (Part 2)

Why Paper Discolours (Part 1)
Why Paper Discolours (Part 1)

Mending a Tear in an Aboriginal Drum
Mending a Tear in an Aboriginal Drum

Distortions and Dimensional Changes
in Paper (Part 3)
Distortions and Dimensional Changes
in Paper (Part 3)

Distortions and Dimensional Changes
in Paper (Part 2)

Distortions and Dimensional Changes
in Paper (Part 1)

After treatment
Oscar Cahén: Innovative Conservation
for an Innovative Artist

Rigid Water Gels: New Treatment Options for Paper Conservators

Structural Remedies for Canvas Paintings

Organizing and Preserving Collections - Part 4: Digital-based Material

Organizing and Preserving Collections - Part 3: Photo-based Material

Organizing and Preserving Collections - Part 2: Paper-based Material

First Steps
Organizing and Preserving Collections - Part 1: The First Steps

Natural Dyes
The Use of Natural Dyes in Textile Conservation

A Relocation Project

Challenges of Preserving Contemporary Artwork

Preserve Your Investment through Art Conservation

A Project Completed: Heritage Preserved

Old and New Methods for Cleaning Paintings

I Can See Clearly Now – Or Can I? Part 2

I Can See Clearly Now – Or Can I?

The E.J. Hughes Mural: An Expanded Project

Is She or Is She Not an Emily

Treating Art with Sensitive Media

Malaspina Mural: An Update

For the Artist: Testing Your Materials

Conservator as Art Historian

Alum Sizing and the Art of W.J. Phillips

Treatment of an Elizabeth Keith Wood Block Print

Structural Treatment of an Emily Carr

The Treatment of a Monumental Wall Hanging

Changing Images

Preserving a Rare Record

Gold Leaf: Imitation and Genuine

The Case Against Canvas Backings

Heritage Colours: Research Discovers Original Colours

Lighting Your Art: Balancing Seeing and Protecting

The Double-Sided Emily Carr Painting

Choosing a Period Picture Frame

How to Identify a Picture Frame

Stretching Canvas and Restretching Artwork

Mounting Textiles

Aging Paintings:
Some Causes and Effects

Chine Collé Prints

What's Your Favourite Color?

Backing Removals

Rips, Holes and Tears

Filling in the Gaps

DIY – Preventative Care of Paintings

Frame it Right

Fire, Water and Smoke-Damaged Paintings

Inherent Vice

Saturated Problems:
A Water-Damaged Painting

Moldy Paper

Conserving Time

Conserving Paper: Dos and Don'ts

Repair of Textiles

Conserving Wood

Rescuing Endangered Murals

Repairing Acid-Matte Burn

Art Services & Materials
Exhibition Openings & Events

Conservation Corner Back

New Methods of Conservation Cleaning

by Nadine Power

During cleaning, detail of portrait of “Spanish John MacDonell

During cleaning, detail of portrait of “Spanish John MacDonell, artist unknown (c. 1800), oil on canvas

After cleaning, portrait of “Spanish John” MacDonell

After cleaning, portrait of “Spanish John” MacDonell

Aged, discoloured varnish layers have traditionally been removed with the use of organic solvents – a technique that can be hazardous to both the conservator and the paintings. Advances in conservation science, however, have introduced methods of holding solvents in gels, which allows for greater control of solvent and considerably reduces the quantity of chemical used. During a recent treatment of a portrait of “Spanish John” MacDonell (c. 1800, artist unknown), conservators used gelling techniques to manipulate solvents and safely remove old over-paint and an aged varnish.

The portrait’s subject, Colonel John MacDonell (1728–1810), was a Scottish immigrant to New York who fought in the American Revolutionary War before moving to Upper Canada in 1773.

During the painting’s recent treatment, fragile paint layers and large areas of old over-paint made conventional solvent-cleaning difficult. To make an aged varnish or old over-paint soluble, organic solvents such as alcohols, acetone and xylene are often used. While solvent-based cleaning can be a highly effective and safe cleaning method if used correctly, the chemicals are often hard to control and may damage the paint surface if not handled with skill. Working with solvent fumes can also be a nuisance to conservators, and potentially hazardous to their health when used for extended periods.

The addition of gelling agents to the conservator’s tool box – first popularized by Richard Wolbers from the University of Delaware – has considerably improved varnish removal techniques. Using a gel formulation allows precise application and can improve the safety of the process to the surrounding paint layers. There are further advantages of gelling solvents: far less chemical is required than usual; and much of the chemical is trapped in the gel, reducing the conservator’s exposure to fumes. As well, gels such as Pemulen™ or Carbopol® (commonly found in beauty and food products) are able to hold smaller amounts of solvent to the surface of the varnish, achieving similar or better results than can be accomplished with liquid solvent. When the desired effect has been achieved, the gel is simply wiped away, leaving the paint surface free of the aged varnish.

During the treatment of the Spanish John portrait, gelled benzyl alcohol was used to remove the aged varnish layer. Discoloured over-paint (from previous restorations) was also removed this way, requiring only a somewhat stronger solvent-gel preparation. A low solvent-to-gel ratio, combined with a controlled exposure time, gave this treatment a high degree of precision while requiring fewer chemicals than would typically be needed.

Previously: The Use of Fixatives in the Treatment of Embellished Textiles
Next issue: Treatment of a Chewed Papier-Mâché Sculpture


 Fri, Feb 7, 2014