2.8 Alkali-Soluble Acrylics in Architectural Conservation: Future Research Directions

Society for the Preservation of New England Antiquities
The Getty Conservation Institute

Morgan Phillips
Charles Selwitz
Period of Activity: Current Research

Project Abstract
An experienced objects conservator remarked, with respect to the varied applications for resins in his work, "If I can use B-72, I use B-72." We will probably not find a water-borne resin that has the myriad virtues and broad utility of Rohm and Haas Acryloid B-72, a material that has earned the deserved trust of conservators the world over. Indeed, solvent-borne resins of all chemical classes, such as acrylics and solvent-borne alkyds, set a standard of performance in certain applications that may be hard to equal when using a water-borne resin of the same chemical class. In many instances, however, the fire hazard and toxicity of organic solvents mandate the use of water-borne resins, especially in architectural applications where hundreds of gallons of resin solutions may be used in one treatment. Also, increasingly stringent laws to protect air quality are bringing about the substitution of water-borne resins for their solvent-borne counterparts, and the variety of solvent-borne resins available for architectural applications will surely be reduced.

Apart from these considerations of safety, availability, and environmentally benign character, particular waterborne resins have features that make them function especially well in certain conservation applications. Among these features are particular types of reactivity, and the dual solubility in organic solvents and water. This study addresses the use of ionically solubilized water-borne resins as consolidants for porous materials, mainly architectural plaster. A primary goal is to familiarize the reader with this class of resins and their advantages and limitations, so that the reader may evaluate them for various applications. (For the introduction to the final report.

Primary Publications
Phillips, M., "Water-Borne Consolidants: Ionically Solubilized Coatings Resins for Plaster Consolidation and Other Conservation Treatments," Final Report to the Getty Conservation Institute, May 1991.

Table of Contents:

I. Introduction

II. Water-Borne Resins: Some Fundamental Concepts, Solubility, Loss of Solubility, Classification by Particle Size, Ionic Solubilization, "Alkali-Soluble" and "Water Reducible" Resins, Cross-linking, Ionic Polymers, Quantifying Functionality, Formulations and Rheology

III. Chemical Classes of Water-Borne Consolidants, Properties Desired, Classes Having Desired Properties, Hybrid Polymers

IV. Architectural Plaster Materials, Alkalinity of Plaster, Effects of Plaster Consolidants on Paints and Wallpapers

V. Some Important Crosslinking Reactions, Covalent Crosslinking not Involving Metals, Crosslinking Via Metal Compounds, Auto-oxidative Crosslinking

VI. Sampling and Screening Sampling, Screening Tests, Evaluation of Performance

VII. The Likelihood of "Spinoffs," Elimination of Toxicity Problems, Consolidation, and Readhesion of Paints, A Thought About Washing Papers, Wallpapers, Desalination of Porous Objects Desalination of Porous Objects;, Waterlogged Wood, Strippable Coatings, Strippable Coatings, ; Facing Adhesives, Some Possible Uses in Wood Consolidation, Some Other "Spinoffs" of This Study, Just Guesses".