Photoluminescence Micro-imaging Sheds New Light on the Development of Metal Soaps in Oil Paintings

In a cultural heritage context, fatty acids are usually found as breakdown products of lipid-containing organic remains in archaeological findings, binders in aged oil paintings, and additives in modern art-related materials. They may further interact with the ionic environment transforming into metal soaps, a process that has been recognized as a threat in aged paintings but has received less attention in archaeological objects. The investigation of the above related categories of materials with infrared spectroscopy can provide an overall picture of the organic components’ identity and demonstrate their condition and prehistory. The capability of investigating and distinguishing fatty acids and their metal soaps through their rich infrared features, such as the acidic carbonyl, the carboxylate shifts, the variable splits of alkyl chain stretching, bending, twisting, wagging, and rocking vibrations, as well as the hydroxyl peak envelopes and acid dimer bands, allows for their direct detailed characterization. This paper reviews the infrared spectra of selected saturated fatty monoacids and diacids, and their corresponding sodium, calcium, and zinc salts and, supported by newly recorded data, highlights the significance of their spectroscopic features.

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Drying Oil and Natural Varnishes in Paintings: A Competition in the Metal Soap Formation

Coatings ◽

10.3390/coatings11020171 ◽

2021 ◽

Vol 11 (2) ◽

pp. 171

Author(s):

Tommaso Poli ◽

Oscar Chiantore ◽

Eliano Diana ◽

Anna Piccirillo

Keyword(s):

Paint Film ◽

Metal Soap ◽

Oxidation Processes ◽

Oil Paintings ◽

Drying Oil ◽

Formation Kinetics ◽

Natural Resins ◽

Metal Soaps ◽

Main Components ◽

Hydrolysis Of

Metal soaps formation is a well-known issue in oil paintings. Along the lifetime of the painting, carboxylic acids coming from drying oil (free fatty acids, acids from hydrolysis of triglycerides and from oxidation processes) can react with cations of some pigments (in particular, smalt, lead white and zinc white) forming the related carboxylic salts. As observed by many authors, the formation of these carboxylates, with the tendency to migrate and to aggregate, not only modifies the behavior and the aspect of the paint film but also complicates the cleaning approach. In previous works we have demonstrated that a similar pigment reactivity is possible even in presence of natural resins (such as colophony, dammar, mastic, etc) historically used as final varnishes on paintings. In this case, in the reactions the terpenic acids, among the main components of the resins, are involved. In this work, the carboxylates formation kinetics has been studied starting from two representative acids (palmitic and abietic) of painting oils and natural varnishes. Successively, the reactivity of the palmitic acid with the potassium abietate and of the abietic acid with the potassium palmitate has been verified. This investigation aims at clarifying in which way terpenic acids can be involved in the metal soaps reactivity confirming that also surface varnishes may play a significant role in the carboxylates formation and reactivity. It is important to keep in mind that a finishing varnish can be removed and reapplied many times during the lifetime of a painting, thus renewing the provision of reactive terpenic acids at the interface of the painted layers.

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The influence of commercial primed canvases in the manifestation of metal soaps protrusions in Georgia O’Keeffe’s oil paintings

Heritage Science ◽

10.1186/s40494-020-00451-7 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Annette S. Ortiz Miranda ◽

Dale Kronkright ◽

Marc Walton

Keyword(s):

Fatty Acids ◽

Free Fatty Acids ◽

Santa Fe ◽

Metal Carboxylates ◽

Similar Morphology ◽

Oil Paintings ◽

Different Types ◽

Georgia O'keeffe ◽

Ft Ir ◽

Metal Soaps

Abstract During a routine condition survey in 2007 at the Georgia O’Keeffe Museum in Santa Fe, micro-protrusions were found scattered across the surfaces of the artist’s oil paintings produced between 1920 and 1950. In many of her works, including Pedernal (1941) and A Man from the Desert (1941), lead soaps were found aggregated at the painting surface, forcing the surrounding paint to deform into pin-sized protrusions. The structure and composition of the protrusions was analyzed to determine why they formed. Microsamples were removed from four of O’Keeffe’s paintings and investigated using a combination of SEM–EDX, GC–MS, and FT-IR. The combined GC–MS and FT-IR results indicate that the protrusions contain primarily lead carboxylates. The results obtained for a series of ground samples removed from four different paintings were then compared with samples collected from a commercially pre-primed canvas roll found in the artist’s house in Ghost Ranch, NM. We identified two different types of canvases: i) a commercially pre-primed canvas and ii) artist primed canvas. This commercially pre-primed canvas roll has a similar morphology to the ground layers in her paintings that contain protrusions additionally these grounds were found to contain an excess of free fatty acids and metal carboxylates (lead soaps) based on a comparison to canvases the artist primed herself. Based on the analytical results from the four paintings and the commercial pre-primed canvas, we concluded that the artist’s use of this particular commercially pre-primed canvas between 1920 and 1950 play an important role in the observed micro-protrusions.

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Formation of Metal Soaps In Oil Paintings Under Variable Environmental Conditions

10.21203/rs.3.rs-667290/v1 ◽

2021 ◽

Author(s):

M. Piovesan ◽

Marta Pérez-Estébanez ◽

M. San Andrés-Moya

Keyword(s):

Relative Humidity ◽

Environmental Conditions ◽

Metal Soap ◽

Oil Paintings ◽

Lead And Zinc ◽

Temperature Ageing ◽

Lead Zinc ◽

Metal Soaps ◽

Titanium White ◽

Cold Pressed

Abstract Formation of metal soaps in model paintings under cyclic temperature and relative humidity conditions has been studied by ATR-FTIR and compared with the standard controlled conditions generally maintained in many museums and storerooms. Three different white pigments (lead, zinc and titanium white) and two types of linseed oils (cold-pressed and alkali-refined) have been tested. The behaviour in short times (up to 6 weeks) depends on the pigment and environmental conditions. The relative humidity conditions have been shown to influence the metal soap formation in more degree than the temperature. Ageing under low cyclic relative humidity (30-50%) promotes metal soap formation in both lead and zinc white pigments, compared to high relative humidity (50-90%) conditions. Besides, the formation of zinc soaps continues for 6 weeks when low cyclic relative humidity is used, but it stops after 3 weeks under the other ageing conditions studied.

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Microspectroscopic Investigation of Metal Soaps in Oil Paintings--a Case Study on late 19th Century Cobalt Green ((CoxZn1-xO) Paint

Microscopy and Microanalysis ◽

10.1017/s1431927618011248 ◽

2018 ◽

Vol 24 (S1) ◽

pp. 2152-2153

Author(s):

Xiao Ma ◽

Selwin Hageraats ◽

Victoria Beltran ◽

Mathieu Thoury ◽

Matthieu Refregiers ◽

...

Keyword(s):

19Th Century ◽

Late 19Th Century ◽

Oil Paintings ◽

Metal Soaps

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Characterizing Color Quality, Damage to Artwork, and Light Intensity of Multi-Primary LEDs for Museums

Heritage ◽

10.3390/heritage4010011 ◽

2021 ◽

Vol 4 (1) ◽

pp. 188-197

Author(s):

Dorukalp Durmus

Keyword(s):

Energy Efficiency ◽

Appearance Model ◽

Light Sources ◽

Great Flexibility ◽

Oil Paintings ◽

Damage Reduction ◽

Output Variability ◽

Color Quality ◽

Trade Offs

Light causes damage when it is absorbed by sensitive artwork, such as oil paintings. However, light is needed to initiate vision and display artwork. The dilemma between visibility and damage, coupled with the inverse relationship between color quality and energy efficiency, poses a challenge for curators, conservators, and lighting designers in identifying optimal light sources. Multi-primary LEDs can provide great flexibility in terms of color quality, damage reduction, and energy efficiency for artwork illumination. However, there are no established metrics that quantify the output variability or highlight the trade-offs between different metrics. Here, various metrics related to museum lighting (damage, the color quality of paintings, illuminance, luminous efficacy of radiation) are analyzed using a voxelated 3-D volume. The continuous data in each dimension of the 3-D volume are converted to discrete data by identifying a significant minimum value (unit voxel). Resulting discretized 3-D volumes display the trade-offs between selected measures. It is possible to quantify the volume of the graph by summing unique voxels, which enables comparison of the performance of different light sources. The proposed representation model can be used for individual pigments or paintings with numerous pigments. The proposed method can be the foundation of a damage appearance model (DAM).

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Molecular association of normal alkanoic acids with their thallium(I) salts: a new homologous series of fatty acid metal soaps

The Journal of Lipid Research ◽

10.1016/s0022-2275(20)37448-4 ◽

1997 ◽

Vol 38 (2) ◽

pp. 361-372

Author(s):

M Fernández-García ◽

M V García ◽

M I Redondo ◽

J A Cheda ◽

M Fernández-García ◽

...

Keyword(s):

Fatty Acid ◽

Homologous Series ◽

Molecular Association ◽

Alkanoic Acids ◽

Metal Soaps

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Revealing the Fugitive Palette of the Early American South: A SERS Study of Eighteenth-century Oil Paintings

Studies in Conservation ◽

10.1080/00393630.2021.1961391 ◽

2021 ◽

pp. 1-13

Author(s):

Marisa A. Choffel ◽

Carolyn G. Farling ◽

Kristen A. Frano ◽

Mary K. Matecki ◽

Zhaoyun Zheng ◽

...

Keyword(s):

Eighteenth Century ◽

American South ◽

Oil Paintings ◽

Early American

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The Tercentenary Conversazione, 23 July 1960

Notes and Records the Royal Society journal of the history of science ◽

10.1098/rsnr.1961.0004 ◽

1961 ◽

Vol 16 (1) ◽

pp. 25-30 ◽

Cited By ~ 1

Keyword(s):

Royal Academy ◽

Chemical Society ◽

Southern Chile ◽

Architectural Drawings ◽

Geological Society ◽

Oil Paintings ◽

Royal Astronomical Society ◽

Meeting Room ◽

The World ◽

Antarctic Expedition

The Conversazione on Saturday 23 July, honoured by the presence of H.R.H. The Prince Philip, Duke of Edinburgh, was the principal occasion during the Celebrations when the Society was able to entertain its guests within Burlington House. This was made possible by the generous co-operation of the neighbouring Societies in Burlington House, and the willingness of the Presidents and Councils of the Society of Antiquaries, the Royal Academy of Arts, the Royal Astronomical Society, the Chemical Society, the Geological Society and the Linnean Society not only to open their rooms but also to arrange appropriate exhibits for the occasion. Some 2000 persons attended and in addition to the scientific exhibits they were able to view the Academy’s i960 Summer Exhibition of oil paintings, water colours, pastels, tempera and miniatures; drawings, engravings, etchings; sculpture; architectural drawings and models in the main galleries of the Royal Academy of Arts. Two colour films, each relating to expeditions directly sponsored by the Society, were on view during the evening, Halley Bay, prepared by members of the Society’s I.G.Y. Antarctic Expedition, was shown in the Meeting Room of the Society of Antiquaries and South from Chiloe , which described the Society’s expedition to Southern Chile to study biological and geological problems among the islands of Western Patagonia, was shown in the Meeting Room of the Geological Society. In the Royal Society’s own rooms there were displayed some three hundred congratulatory addresses as well as the several gifts received by the Society from Academies, Universities and Learned Institutions from all over the world on the occasion of the Tercentenary Celebrations (see pp. 103-113). These were arranged around the walls and on tables in the Library making a very impressive display. The Society’s own Treasures, the Mace, the Charter Book, the manuscript of the Principia and Newton’s telescope were also on view and in addition there was a small exhibit of books and pamphlets illustrating attacks made on the Society during its history. This was arranged by Professor E. N. da C. Andrade who also lent the material for it.

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