Elle Friedberg
Before treatment, normal illumination.
BOWL
Slip decorated pearlware.
Materials
1800-1820
Year
Staffordshire, England
Maker
Collection
Winterthur Museum, Garden, & Library
This buff-bodied earthenware bowl belongs to a group of ceramics called factory-made slipware widely produced from 1760 to 1990. A looped pattern known as “earthworm” or “cabling” was applied over the yellow band of slip followed by an overall pearlware glaze. These dipped wares were strictly utilitarian, had the cheapest decoration, and are the most frequently mentioned items in merchants' and potters' documents during this period. Bowls were used for a variety of functions including eating, drinking, serving, and food preparation. It is hypothesized this was a punch bowl.
Before treatment, normal illumination.
Detail of haloed staining on exterior of bowl around crack.
CONDITION BEFORE TREATMENT
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Structural instability caused by four cracks on the bowl walls and multiple cracks around footrim
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Overall staining giving the bowl a beige appearance on the interior and exterior
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High contrast grime in the cracks in the bowl
Detail of vertical cracks and losses in the glaze.
Photo: Jacinta Johnson
Detail of cracking above footrim.
Photo: Jacinta Johnson
Photomicrograph of the abrasion in the central well of the bowl. Photo: Jacinta Johnson
Photomicrograph of bowl’s central well showing abrasions in the glaze where the ceramic body was exposed and darkened from grime accumulation, viewed at a magnification of 90x.
Photo: Jacinta Johnson
TREATMENT STEPS
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Dry cleaned the surface with a soft brush
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Wet cleaned the surface with 70:30 ethanol: water followed by sodium citrate (0.5%, pH 8)
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Tested chelators for stain reduction and established EDTA as a successful solution
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Followed stain reduction procedure with sequential use of a chelator via various poultice applications (KayDry tissue, 4.5% agarose gel, chromatography paper, paper pulp)
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Used oxidizing bleach and rinse solution at appropriate pH via poultice application
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Consolidated cracks with dilute Paraloid B72
IMAGES OF STAIN REMOVAL IN PROCESS
After initial dry cleaning with soft brush and wet cleaning with 70:30 ethanol:water followed by sodium citrate (0.5%, pH 8).
After first application of strips of KayDry with EDTA.
After use of agarose gel in EDTA and KayDry tissue.
After use of agarose gel in EDTA and chromatography paper.
After use of EDTA and paper pulp (3 rounds) and rinse step with deionized water and paper pulp.
After carbamide peroxide bleach treatment (2 rounds).
Additional images and videos. Use arrows to scroll and click on images to expand.
TREATMENT RESULTS
Before treatment.
After treatment.
Before treatment.
After treatment.