The Effect of Chemical Treatments on the Separation of Calcium Stearate for The Restoration and Prevention of Metal Soap Formation in Oil Paintings
School Name
Spring Valley High School
Grade Level
11th Grade
Presentation Topic
Chemistry
Presentation Type
Non-Mentored
Abstract
Saponification, the formation of metal soap in oil paintings, results from incomplete drying of oils and pigments binding in a chain reaction. Metal soap, a compound of metallic salt and fatty acid, forms when metal ions bind with free fatty acid chains from drying and glazing medium. Saponification leads to dark spots, color loss, and degradation in paintings, causing unintended differences from the artist's original vision. Techniques such as optical microscopy, SEM-BSE, FTIR, and others have been employed to study saponification, revealing common metals like zinc, copper, lead, aluminum, and iron binding with fatty acids to create compounds in oil paint, but even then, scientists have not yet been able to assemble a technique to remove metal soap from oil paintings. Thus, the purpose of this experiment was to find a compound to separate the metal Ca and the fatty acid in linseed oil in calcium stearate (C36H70CaO4). It was hypothesized that if hydrochloric acid (HCl), acetone (C3H6O), and citric acid HOC(CH2CO2H)2 were used to separate C36H70CaO4 in linseed oil, then C3H6O would extract the most parts per million (ppm) of calcium, therefore purifying the greatest amount of free fatty acid during the reaction due to its polar structure allowing for metal-acetone interactions, ability to act like a ligand, and the likeliness for C3H6O to form a complex with metals with an empty d orbital. C36H70CaO4 was dissolved in H2O and water-miscible linseed oil, then an attempt was made to extract Ca from the solution using H2O, HCl, C3H6O, and HOC(CH2CO2H)2. A one-way ANOVA test was conducted to determine statistical significance resulting in a p-value < 0.00001 meaning the null hypothesis was able to be rejected, however, a post-hoc Tukey test revealed significance was not present between the HCl added and HOC(CH2CO2H)2 added groups. The results of this experiment signify that C3H6O could be used as a chemical treatment for saponification.
Recommended Citation
Phan, Vianne, "The Effect of Chemical Treatments on the Separation of Calcium Stearate for The Restoration and Prevention of Metal Soap Formation in Oil Paintings" (2024). South Carolina Junior Academy of Science. 469.
https://scholarexchange.furman.edu/scjas/2024/all/469
Location
RITA 365
Start Date
3-23-2024 12:00 PM
Presentation Format
Oral and Written
Group Project
No
The Effect of Chemical Treatments on the Separation of Calcium Stearate for The Restoration and Prevention of Metal Soap Formation in Oil Paintings
RITA 365
Saponification, the formation of metal soap in oil paintings, results from incomplete drying of oils and pigments binding in a chain reaction. Metal soap, a compound of metallic salt and fatty acid, forms when metal ions bind with free fatty acid chains from drying and glazing medium. Saponification leads to dark spots, color loss, and degradation in paintings, causing unintended differences from the artist's original vision. Techniques such as optical microscopy, SEM-BSE, FTIR, and others have been employed to study saponification, revealing common metals like zinc, copper, lead, aluminum, and iron binding with fatty acids to create compounds in oil paint, but even then, scientists have not yet been able to assemble a technique to remove metal soap from oil paintings. Thus, the purpose of this experiment was to find a compound to separate the metal Ca and the fatty acid in linseed oil in calcium stearate (C36H70CaO4). It was hypothesized that if hydrochloric acid (HCl), acetone (C3H6O), and citric acid HOC(CH2CO2H)2 were used to separate C36H70CaO4 in linseed oil, then C3H6O would extract the most parts per million (ppm) of calcium, therefore purifying the greatest amount of free fatty acid during the reaction due to its polar structure allowing for metal-acetone interactions, ability to act like a ligand, and the likeliness for C3H6O to form a complex with metals with an empty d orbital. C36H70CaO4 was dissolved in H2O and water-miscible linseed oil, then an attempt was made to extract Ca from the solution using H2O, HCl, C3H6O, and HOC(CH2CO2H)2. A one-way ANOVA test was conducted to determine statistical significance resulting in a p-value < 0.00001 meaning the null hypothesis was able to be rejected, however, a post-hoc Tukey test revealed significance was not present between the HCl added and HOC(CH2CO2H)2 added groups. The results of this experiment signify that C3H6O could be used as a chemical treatment for saponification.
