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Protrusions/Aggregates

Tiny, translucent or opaque white globules in the paint which are breaking through the surface of the paint layer (protruding masses). They are often the size of a pinhead (50-300µm), but can be larger. Their loss from the paint surface leads to a crater-like surface.

Related terms

Metal soaps
Protruding masses
Efflorescent particles
Small spheres
Aggregates of small white particles
Translucent pustules
Agglomerates
Small opaque white dots
Opaque white spots on a macroscopic level

COMMENT: COMMENT: Protrusions are caused by the formation of metal carboxylates from metal ions and fatty acids within the paint layer which are clustered to form protrusions and migrate to the surface of the paint.

Literature

Helwig K., Poulin J., Corbeil M.C., Moffat E., Duguay D., Conservation issues in several twentieth-century Canadian oil paintings: The role of zinc carboxylate reaction products, 2014, in: Issues in Contemporary Oil Paint, pp 167-184

Duffy M., Martins A., Boon J.J., Metal soaps and visual changes ina painting by René Magritte- The Menaced Assassin, 1927, 2014, in: Issues in Contemporary Oil Paint, pp197-203

Boon JJ., Keune K., Zucker J., Imaging analytca studis of lead soaps aggregating in preprimed canvas used by the Hudson River School painter FE Church, 2005, in: Microscience Microanal 11 (suppl 2), pp 444-445

Faubel W., Simn R., Heissler S., Friedrich F., Weidler PG., Becker J., Schmidt W., Protrusions in a painting by Max Backmann examined with confocal u-XRF, 2011, in: Anal Atomic Spectrum 26 (5), pp 942-948

Higgitt C., Spring M., Saunders D., Pigment-medium interactions in oil paint films containing red lead or lead-tin yellow, 2003, in: National Gallery Technical Bulletin 24, pp 75-95

Noble P., Boon JJ. , Metal soap degradation of oil paintings: aggregates, increased transparency and efflorescence, 2007, in: AIC Paintings Specialty Group postprints 19, pp 1-15

O'Donoghue E., Johnson AM., Mazurek J., Preusser F., Schilling M., Walkton MS., Dictated by media: Conservation and technical analysis of a 1938 Joan Miró canvas painting, 2006, in: Studies in Conservation 51(2), pp 66-68

Osmond G., Keune K., Boon JJ. , A study of zinc soap aggregates in a late 19th century painting by R.G. Rivers at the Queensland Art Gallery, 2005, in: AICCM bulletin 29, pp 37-46

van der Weerd J., Geldof M., van der Loeff L.S., Meeren R.M.A., Boon J.J., Zinc soap aggregate formation in 'Falling Leaves' (Les alyschamps) by Vincent van Gogh, 2003, in: Kunsttechnologie Konservierung 17(2), pp 407-416

Keune K., Boon J.J., Analystical imaging studies of cross sections of paintings affected by lead soap aggretate formation, 2007, in: Studies in Conservation 52, pp 161-176

Mecklenburg M.F., Tumosa C.S., Vicenzi E.P., The influence of pigment and ion migration on the durability of drying oil and alkyd paints, 2013, in: New Insights into the cleaning of paintings. Proceedings from the cleaning 2010 international conference Universidad Politécnica de Valencia and Museum Conservation Institute. Smithsonian Institution Scholarly Press, Washington DC, pp. 59-67

Ferreira E.S.B. Boon J.J., Stampanoni M., Marone, F., Study of the mechanism of formation of calcium soaps in an early 20th-century easel painting with correlative 2D and 3D microscopy, 2011, in: Preprints of ICOM-CC Lisbon, Icom committee for conservation 16th triennial meeting, Lisbon 2011,

Protrusie

Minuscule, doorzichtige of opake witte uitsteeksels in de verf die door het oppervlak van de verflaag breken. Vaak hebben ze grootte van een speldekop (50-300 µm), maar ze kunnen ook groter zijn. Als de protrusies verloren zijn gegaan laat dit vaak een krater-achtig oppervlak achter.

Opmerking: Protrusies worden veroorzaakt door de formatie van metaal carboxylaten uit metaal ionen en vetzuren in de verflaag, die clusteren om protrusies te vormen die vervolgens door het verfoppervlak kunnen breken.

Literatuur

Helwig K., Poulin J., Corbeil M.C., Moffat E., Duguay D., Conservation issues in several twentieth-century Canadian oil paintings: The role of zinc carboxylate reaction products, 2014, in: Issues in Contemporary Oil Paint, pp 167-184

Duffy M., Martins A., Boon J.J., Metal soaps and visual changes ina painting by René Magritte- The Menaced Assassin, 1927, 2014, in: Issues in Contemporary Oil Paint, pp197-203

Boon JJ., Keune K., Zucker J., Imaging analytca studis of lead soaps aggregating in preprimed canvas used by the Hudson River School painter FE Church, 2005, in: Microscience Microanal 11 (suppl 2), pp 444-445

Faubel W., Simn R., Heissler S., Friedrich F., Weidler PG., Becker J., Schmidt W., Protrusions in a painting by Max Backmann examined with confocal u-XRF, 2011, in: Anal Atomic Spectrum 26 (5), pp 942-948

Higgitt C., Spring M., Saunders D., Pigment-medium interactions in oil paint films containing red lead or lead-tin yellow, 2003, in: National Gallery Technical Bulletin 24, pp 75-95

Noble P., Boon JJ. , Metal soap degradation of oil paintings: aggregates, increased transparency and efflorescence, 2007, in: AIC Paintings Specialty Group postprints 19, pp 1-15

O'Donoghue E., Johnson AM., Mazurek J., Preusser F., Schilling M., Walkton MS., Dictated by media: Conservation and technical analysis of a 1938 Joan Miró canvas painting, 2006, in: Studies in Conservation 51(2), pp 66-68

Osmond G., Keune K., Boon JJ. , A study of zinc soap aggregates in a late 19th century painting by R.G. Rivers at the Queensland Art Gallery, 2005, in: AICCM bulletin 29, pp 37-46

van der Weerd J., Geldof M., van der Loeff L.S., Meeren R.M.A., Boon J.J., Zinc soap aggregate formation in 'Falling Leaves' (Les alyschamps) by Vincent van Gogh, 2003, in: Kunsttechnologie Konservierung 17(2), pp 407-416

Keune K., Boon J.J., Analystical imaging studies of cross sections of paintings affected by lead soap aggretate formation, 2007, in: Studies in Conservation 52, pp 161-176

Mecklenburg M.F., Tumosa C.S., Vicenzi E.P., The influence of pigment and ion migration on the durability of drying oil and alkyd paints, 2013, in: New Insights into the cleaning of paintings. Proceedings from the cleaning 2010 international conference Universidad Politécnica de Valencia and Museum Conservation Institute. Smithsonian Institution Scholarly Press, Washington DC, pp. 59-67

Ferreira E.S.B. Boon J.J., Stampanoni M., Marone, F., Study of the mechanism of formation of calcium soaps in an early 20th-century easel painting with correlative 2D and 3D microscopy, 2011, in: Preprints of ICOM-CC Lisbon, Icom committee for conservation 16th triennial meeting, Lisbon 2011,