Editing Gesso

{{Short description|Paint primer composed of a white pigment and a binder}}
{{for|the Italian geology term|gypsum}}
[[file:St. Michael & All Angels Church, Lyndhurst -Gesso Panel.JPG|thumb|A restored gesso panel representing [[Martin of Tours|St. Martin of Tours]], from St. Michael and All Angels Church, Lyndhurst, Hampshire]]

'''Gesso''' ({{IPA|it|ˈdʒɛsso}}; '[[chalk]]', from the {{langx|la|[[gypsum]]}}, from {{langx|el|γύψος}}), also known as "glue gesso" or "Italian gesso",<ref>[https://books.google.com/books?id=o23u0SuRLxsC&pg=PA321 ''The Painter's Handbook: A Complete Reference'' by Mark David Gottsegen. p. 321] {{webarchive |url=https://web.archive.org/web/20150603155459/https://books.google.com/books?id=o23u0SuRLxsC&pg=PA321 |date=June 3, 2015 }}</ref> is a white [[paint]] mixture used to coat rigid surfaces such as wooden [[panel painting|painting panels]] or [[masonite]] as a permanent absorbent [[primer (paint)|primer]] substrate for [[painting]]. It consists of a [[binder (material)|binder]] mixed with [[chalk]], [[gypsum]], [[pigment]], or any combination of these.<ref>{{cite book|author=Daniel Varney Thompson|url=https://books.google.com/books?id=I1DFuGQeG10C&pg=PA32|title=The materials and techniques of medieval painting|date = January 1956|page=32| publisher=Courier Corporation |isbn = 9780486203270|access-date=2014-04-09|via=Books.google.com}}</ref>

Gesso is used in painting as a preparation for any number of substrates such as wood panels, [[canvas]] and sculpture as a base for paint and other materials that are applied over it.

== Characteristics ==

The colour of gesso is usually white or off-white. Its absorbency makes it work with all painting media, including water-based media, different types of [[tempera]] and [[oil paint]].

Mixing and applying it is a craft in itself, as it is usually applied in ten or more extremely thin layers. The hide glue mixture used to make the traditional gesso is rather brittle and susceptible to cracking, thus making it suitable for rigid surfaces only.

When painting, there are several advantages to using gesso. It provides a strong foundation for the paint to adhere to, prevents the paint from soaking into the surface, and can also be used to achieve a desired texture or surface finish. Furthermore, gesso can help to extend the life of a painting by acting as a barrier to protect it from moisture, dust, and ultraviolet (UV) light.<ref>{{Cite web |last1=siddiqui |first1=Ubaid |last2=Mapari |first2=Muskan |date=2023-02-08 |title=What Is Gesso: Everything You Should Know | work = Inkbyhand |url=https://inkbyhand.com/what-is-gesso-everything-to-know/ |access-date=2023-02-13 |language=en-US}}</ref>

== Composition ==
[[file:Gesso acrylic brush.jpg|thumb|Acrylic gesso]]

Gesso is traditionally a mix of an animal glue binder (usually [[rabbit-skin glue]]), chalk, and white pigment.

For priming flexible [[canvas]], an [[emulsion]] of gesso and [[linseed oil]], also called "half-chalk ground", is used.<ref>[https://web.archive.org/web/20160624135136/https://books.google.com/books?id=o23u0SuRLxsC&pg=PA64 ''The Painter's Handbook: A Complete Reference'' by Mark David Gottsegen, p. 64]</ref>

Acrylic gesso is a mixture of white pigment and some kind of filler (chalk, silica, etc.) and [[acrylic resin]] dispersed in water. It produces a soft, flexible non-absorbent surface that is technically not ''gesso'' (although it is commonly called that by its manufacturers).<ref>[https://books.google.com/books?id=o23u0SuRLxsC&pg=PA321 ''The Painter's Handbook: A Complete Reference'', by Mark David Gottsegen. p. 321] {{webarchive |url=https://web.archive.org/web/20150603155459/https://books.google.com/books?id=o23u0SuRLxsC&pg=PA321 |date=June 3, 2015 }}</ref><ref>{{cite book|url=https://books.google.com/books?id=eQkf05ZPoysC&pg=PA56 |author=Michael Friel |title=Still Life Painting Atelier: An Introduction to Oil Painting|publisher= Random House Digital, Inc| page =58 |via=Books.google.com |date=2010 |isbn=9780823034086 |access-date=2014-04-09}}</ref> It can contain calcium carbonate (CaCO<sub>3</sub>) to increase the absorbency of the primer coat as well as [[titanium dioxide]] or "titanium white" as a whitening agent. It is sold premixed for both [[sizing]] and priming panels and flexible [[canvas]] for [[painting]]. Art supply manufacturers market canvases pre-primed with acrylic gesso. Acrylic gesso can be colored, either commercially by replacing the titanium white with another pigment, such as [[carbon black]], or by the artist directly, with the addition of an [[acrylic paint]]. Acrylic gesso can be odorous, due to the presence of [[ammonia]] or [[formaldehyde]], which are added in small amounts as preservatives. Acrylic gesso's non-absorbent acrylic polymer base makes it incompatible with media that require an absorbent substrate, such as egg [[tempera]].<ref>{{cite book|url=https://books.google.com/books?id=CU56YgWzIM8C&pg=PA33 |author=Altoon Sultan|title= Luminous Brush: Painting with Egg Tempera|year=1999| page =33 |publisher=Altoon Sultan |isbn=9780823028887|via=Books.google.com |access-date=2014-04-09}}</ref> ''The Painter's Handbook'' notes a problem with using oil paints over an acrylic gesso ground instead of a traditional [[oil ground]], citing a mismatch in flexibility that over time could cause the oil paint to delaminate.<ref>{{Cite book| edition = Revised, Expanded| publisher = Watson-Guptill| isbn = 978-0-8230-3496-3| last = Gottsegen| first = Mark David| title = Painter's Handbook: Revised and Expanded| location = New York| date = 2006| page=60}}</ref>

== Uses ==

[[sculpture| Sculptors]] may use gesso to prepare the shape of a final sculpture (fused bronze) or directly as a material for sculpting. Gesso can also be used as a layer between sculpted wood and gold leaf.<ref>{{cite web |title =What Does That Do: Gesso Carving Chisels  |url =http://www.theconservationcenter.com/articles/2017/11/27/what-does-that-do-gesso-carving-hooks |location =Chicago |publisher =The Conservation Center |date =November 29, 2017 |access-date =May 23, 2020 }}</ref> In this case, a layer of refined and coloured clay called [[Armenian bole | bole]] is used to cover the gesso before applying the gold.<ref>{{cite book | last = Thompson | first = Daniel V. | title = The Materials and Techniques of Medieval Painting | publisher = Dover Publications | year = 2012 | page=219 | isbn = 9780486142036 |url =https://books.google.com/books?id=MU68AQAAQBAJ&dq=gold+leaf+gesso&pg=PA219}}</ref> Bole is usually red in colour.

Gesso can also serve as a base on three-dimensional surfaces for the application of paint or [[gold leaf]].<ref>{{cite book |url=https://books.google.com/books?id=OHa9dxrh5g0C&pg=PA148 |title =Lettering & Calligraphy Workbook |year =2006 |publisher = Diagram Group | page= 148 |isbn =9781402741012 |via=Books.google.com |access-date=2014-04-09}}</ref>

== References ==

{{refs}}

== External links ==

* {{commonscat-inline}}
* [http://www.jtresser.com/GILDERTIPS.html "The Technique of Raised Gilding", Jerry Tresser, 1992] {{Webarchive|url=https://web.archive.org/web/20150328193511/http://www.jtresser.com/GILDERTIPS.html |date=2015-03-28 }}
* {{cite journal|author=Crane, Walter|author-link=Walter Crane|title=Gesso Work|journal=The Studio|volume=1|issue=2|date=May 1893|pages=45–49|url=https://babel.hathitrust.org/cgi/pt?id=pst.000068818081;view=1up;seq=57}}

[[Category:Gilding]]
[[Category:Painting materials]]
[[Category:Italian words and phrases]]