Hidden Complexities

When Al Loving’s Blue Rational/Irrational from 1969 entered the paintings conservation lab, we thought it would be a relatively straightforward cleaning. The bigger challenge appeared to be retouching some dark scuffs and abrasions on the pale monochromatic paint surface. But once we started the cleaning tests, the opposite turned out to be true.

The crystalline-like abstract painting is constructed from two mirrored, irregular hexagonal canvases, each mounted on separate stretchers that are intended to be shown as one overall composition joined at the center. Loving’s use of bold, pure color and geometric forms creates a tension between the flatness and the spatial illusion of the entire piece. Hard-edged bands of color seem to float over a thin, rapidly applied sky-blue background.

Painted bands defining space are composed of thicker acrylic paint. Each color and band was made by masking off the area with tape to create hard, crisp edges. They were applied sequentially, and in some cases entirely painted over, indicating that the painting and spatial definition were evolving as he was working. According to a family member interviewed before the treatment, Loving’s working process included holding and turning a prism (from a chandelier) near his eyes to make virtual color choices for his paintings.

While this 40-year-old acrylic painting was in good structural condition, the unvarnished surface displayed accumulations of gray grime, dark smudges around the edges from handling, insect droppings, water stains, and minor scuffs that visually compromised Loving’s hard-edged abstraction. Additionally, on the right panel, a series of long, arcing horizontal scuffs were present in the blue background, compressing the thinly painted cotton canvas fibers under the paint layer.

Over the past decade, conservators and conservation scientists have performed groundbreaking work in the cleaning of acrylic paintings. Though ongoing, these studies have increased our understanding of the material and aging properties of acrylic paints and methods for treatment.

Acrylic paints are complex mixtures of acrylic resins, pigments, and various additives that can include pH buffers, surfactants, wetting agents, plasticizers, defoaming agents, thickeners, fungicides, and antifreezing agents. Pigments provide the color, while the additives deliver the necessary properties to produce flexible, workable, and stable paint films. The main components—acrylic resins and pigments—are relatively stable. However, over time, the additives can migrate out of the paint, attracting grime, creating embrittlement, and altering the surface gloss. Water-based cleaning systems commonly used for removing grime can mobilize and strip away these additives, creating greater instability over time.

One of the most promising approaches arising from conservation research is to determine the pH (concentration of hydrogen ions) and conductivity (overall ionic concentration) of the paint surface, then match the cleaning system with those same parameters. Research has shown that less material is drawn out of acrylic paint with this method—think of how conditioner is pH balanced and contains ingredients designed not to strip oil from your hair.

However, in this painting, one complicating factor was unanticipated. Examination with magnification showed that Loving used an off-white primer before applying the blue background color. This ground layer, applied to the canvas, was quite sensitive to water. While the paint layer was unaffected, miniscule fragments of the ground layer were scattered throughout the blue background, seemingly swept up into the paint layer. In small cleaning tests, these fragments appeared to be partially dissolved even with pH-adjusted water. To understand why this was happening, we needed to determine the composition of the fragments.

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Analysis with the museum’s FTIR (Fourier transform infrared spectrometer) revealed that these fragments of primer were composed of kaolin and a drying oil, commonly found in oil-based house primers. It seems likely that the oil primer had not completely dried and began to break apart as Loving applied the thin wash of blue acrylic paint. It is possible that he may have even intended this or at least was not bothered by it. Still, cleaning tests confirmed that the painting could not be cleaned safely unless we used a method to prevent the pH-adjusted water from dissolving the primer fragments.

The method tested to solve this problem involved two steps: first, a nonpolar barrier solvent was administered to penetrate deep into the delicate paint layers to repel the negative effects of water. Then, pH-adjusted water was applied with soft brushes to release the surface dirt, which was then removed with highly absorbent sponges and a specially engineered fabric. After conducting successful tests over larger surface areas, we used a silicon-based solvent that is extremely slow to evaporate (commonly used in the cosmetics industry) to temporarily penetrate the primer fragments to seal off the detrimental effects of the pH-adjusted water. Rachel Childers, third-year intern from the Buffalo Conservation Program, assisted with removing all the smudges, embedded grime, water stains, and accretions from the paint surface using this two-step cleaning technique.

No longer veiled by grime, the painting reveals a remarkable new vibrancy in the color contrasts and an enhanced spatial depth and paint surface. The distracting scuffs, accentuated by the grime, were also considerably lessened with cleaning, simplifying and reducing the amount of inpainting required. This new gift adds to the depth of the collection of works by modern African American artists, such as Aaron Douglas, Jack Whitten, and Norman Lewis. It is on view in the contemporary galleries.    

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Cleveland Art, Sping 2021