Linseed oil paint

from Wikipedia, the free encyclopedia
Pure linseed oil paint is made from cold-pressed, degummed, sterilized and “boiled” linseed oil, which is rubbed with dried and ground earth colors or pigments.

Linseed oil paints are oil paints that are used in handicrafts for the preservation and color design of wood and iron and in art for canvas and panel painting .

For use as an artist's paint in panel painting, see

Linseed oil paints consist of dry pigments or earth colors that are mixed with “boiled” linseed oil and then ground. The more intensively pigments or earth colors are ground with the linseed oil, the more concentrated and covering the color will be. To support the autoxidation process of the linseed oil, between 0.09 and a maximum of 3 percent dry matter is added.

Due to its good hardening properties, linseed oil is mainly used to produce oil paints . However, other hardening vegetable oils are also used. For example, walnut and safflower oil are used when the oil paint should dry up as transparently as possible in order to prevent the yellowing that is common with linseed oil.

Definition

Linseed oil paint

A color is called linseed oil paint when a well-dried pigment or an earthen coloring agent is ground with “boiled” or raw linseed oil as a binder. As a traditionally used mixture of substances for preservation and color design, linseed oil paint is not subject to any standardization or legal regulation. In the course of centuries of experience with linseed oil paint, the "original method of production" , i.e. the "combination of the color material with the binding agent" , was individually modified by each user "often with great secrecy" . The introduction of the industrial production of oil paints in the 19th century required modifications to the traditional composition, so that the original properties of the pure linseed oil paint were gradually changed through the addition of thinners or solvents.

Colors with the addition of linseed oil varnish and thinners

The demand for natural colors has led to the fact that today, in addition to linseed oil paints according to traditional craftsmanship, there are also industrially produced paints that contain, among other things, linseed oil varnish and thinner , and are called "linseed oil paint" by the manufacturer. However, they can differ noticeably from traditional linseed oil paint in terms of their production, composition and properties. The term “linseed oil paint”, but also “paint based on linseed oil” for these solvent-based paints with a proportion of linseed oil varnish is misleading to distinguish them from linseed oil paints, because alkyd resin paints or thick-layer glazes are also made “on the basis” of linseed oil. Good quality linseed oil paint does not require a thinner. If turpentine oil is added during the production of paints using so-called “linseed oil varnish” , this should not act as a solvent as in the case of resins and waxes, but as a diluent . Thinners are used with the aim of diluting viscous paints and linseed oil varnishes in order to improve the penetration of the substances into the substrate. Cold-pressed, low-viscosity linseed oil is more expensive to produce than low-quality linseed oil, which is obtained by chemical extraction using hexane and heating. These oils, obtained by chemical extraction and heating, contain ingredients that prevent the oil from penetrating far without the addition of diluents. These “diluted” oils are called semi-oils . If so-called “paints based on linseed oil” contain harmful solvents and thinners ( VOC ) such as aliphatic hydrocarbons , these must be classified and labeled according to the Ordinance on Hazardous Substances (GefStoffV). In “linseed oil-based paints”, volatile organic compounds serve as “ spreading agents” for viscous derivatives of linseed oil, such as linseed oil varnish, and evaporate completely after a certain period of time. Since added, volatile thinners are less viscous than the linseed oil derivative to be thinned, they can penetrate further into the painting surface. After the added diluents have evaporated, the remaining proportion of binder, which is supposed to surround the pigment particles, is less. However, this does not fully guarantee the preservative properties of linseed oil. Therefore, linseed oil paints with a high proportion of thinners are less resistant and dry more matt because of the lower proportion of binder. Cold-pressed, raw and purified linseed oil has a molecular size of 0.000005 to 0.00001 mm, “cooked” linseed oil has a molecular size of 0.0001 mm. This explains why linseed oil paint can only achieve its excellent preservative effect if the linseed oil as the starting substance is of high quality and therefore has a high penetration capacity without added thinners. However, if thinners such as turpentine oil are used, the rule “ fat on lean ” must be observed. This principle comes from canvas and panel painting and means that as the paint builds up, less and less thinner may be added to the oil paint, so that the paint build-up is prevented from tearing open due to different tensions. The rule “fat on lean” does not play a role in the use of pure linseed oil paint, as linseed oil as a preservative - in contrast to canvas and panel painting - should penetrate the painting ground and therefore no thinners such as turpentine oil should be added to the linseed oil.

properties

Physical and chemical properties of pure linseed oil paints

Linseed oil is both a natural wood preservative for wood and a binding agent for making paints. It is known as a one-part binder . This means that linseed oil and linseed oil paint “dry” and harden through chemical crosslinking to a new substance and not through the volatilization of an added solvent . The chemical conversion of linseed oil to linoxin occurs through the absorption of oxygen ( oxidation ) and through transesterification and radical polymerization of the previously individual molecules. Therefore, the term “drying” is misleading in this context. When using solvents , this is only used to dilute , not to dissolve linseed oil and pure linseed oil paint. No volatile organic compounds are therefore required in the manufacture and use of pure linseed oil paint . Cold-pressed, degummed and sterilized linseed oil is pre-oxidized so that the oxidation and hardening does not take too long. This so-called “cooked” linseed oil is cold-pressed linseed oil that is heated to 130–150 ° C and “blown” with oxygen for 5–6 hours and mixed with 0.1% siccatives . It is therefore not about linseed oil that was actually boiled, because the boiling point of linseed oil is over 316 ° C. The "exemplary solid drying process" that distinguishes linseed oil can only take place "if the linseed oil is of high quality according to the origin of the linseed, after the pressing process and subsequent treatment."

A manufacturer of pure linseed oil paints shows at a trade fair on a three-roller mill how linseed oil paints are ground.

If linseed oil paints are applied too thickly, the upper layer of linoxin prevents oxygen from diffusing, which means that the surface does not harden, but remains liquid and the surface becomes wavy. The ester bonds of the oils contained can hydrolyze with frequent contact with water , which can lead to a washout effect. Due to the ester bond, linseed oil paint is not resistant to acids or bases. Linoxin tends to yellow .

Preservation with pure linseed oil

Pure linseed oil paint is applied after a primer with pure cold-pressed linseed oil in three coats on components outdoors. The extremely low viscosity of pure linseed oil paint enables the linseed oil to penetrate through the previous coats with every coat without the addition of thinners, thus creating a layer-free and film-free structure of the linseed oil preservation. Pure linseed oil paint does not form any distinguishable layers, but instead creates a homogeneous structure of linoxin after its chemical conversion of the linseed oil, which extends from the pores of the wood to the surface of the paint. Since linseed oil expands by around 10% when it is converted to linoxin, the pores of the wood are additionally compressed. Linoxin retains a certain elasticity for decades . Therefore pure linseed oil paints are also very durable outdoors. Pure linseed oil paint is therefore not a coating material within the meaning of § 2 Paragraph 4–6 Solvent-based Paints and Varnishes Ordinance - ChemVOCFarbV (Solvent Ordinance), which forms a film, but rather a substantial combination of linoxin with the painting surface, which therefore neither cracks nor flakes. Cold-pressed, degummed and sterilized linseed oil, "boiled" linseed oil and pure linseed oil paint do not require any volatile solvents to solidify and no thinners to achieve a high penetration depth and are therefore naturally not subject to the solvent ordinance.

maintenance

The preservative properties of cold-pressed, pure linseed oil and its ability to penetrate deep into wood make it possible to refresh the linseed oil preservation even over centuries without having to remove the layers of paint. Historical components, such as windows, which have been painted with linseed oil paint and maintained with linseed oil for more than a century, can therefore still be found in good condition today. Linseed oil paint according to historical composition is a color that can be preserved for a long time through care. Since the oxidation and polymerisation of pure linseed oil paint is an ongoing process, the pigments will chalk on the surface after a few years. This is a sign that the linseed oil paint needs maintenance again. This consists in binding the exposed pigments again with "boiled" linseed oil. Since solvent-free linseed oil paints do not become statically charged and since they have the property of chalking after a few years, these paints look fresh even after years. A new coat of paint on the existing color is only necessary after several years, depending on the weather and color.

Curing

The time it takes for other paint systems that contain solvents to cure has approached the time it takes for linseed oil paint to cure without thinners or solvents due to the EU solvent regulation, as the percentage of permitted solvents has been reduced by law. The time it takes for linseed oil paints to cure without thinners or solvents is not a disadvantage, but means that the preserving linseed oil has more time to penetrate deep into the painting surface before it hardens to linoxin due to the progressive oxidation and polymerization .

Precautions when handling “cooked” linseed oil

Liquid linseed oil and liquid linseed oil paints are only flame retardant. However, under certain conditions, drying natural oils can self-ignite. Cloths, paper or dust wetted with linseed oil should be hermetically sealed or soaked in water, otherwise there is a risk of self-ignition . Rag or paper towels that still contain liquid linseed oil can be spread out flat on the floor outdoors. After they have solidified, they can be disposed of. On the other hand, there is a great danger especially with crumpled rags, paper towels and fibers that have been soaked with “boiled” linseed oil. Here, the heat of reaction is poorly dissipated and this can lead to a build-up of heat. On the other hand, rags that have been soaked with sufficiently pigmented linseed oil paints without thinners or solvents do not pose a fire hazard. Consistent avoidance of the use of rags when handling linseed oil and linseed oil paint is the safest fire protection.

Linseed oil as an additive

Some users add a modified linseed oil to the pure linseed oil paint, which is now known as linseed oil stand oil. In earlier centuries, raw linseed oil was left to stand for a long time in the absence of air to make it. Today, for its production, raw linseed oil is heated to over 260 ° C in the absence of air. The result is a viscous linseed oil derivative that is supposed to achieve a glossy finish, better spreadability and higher water resistance of the paint. The drying process of the paint is, however, prolonged by this addition. According to Kopinski, the shine and flow of the interior oil paint can be enhanced by adding 2 to 3% stand oil. In the case of exterior paints, adding 10 to 15% of the amount of binder can increase the durability of the paint.

application

Historical application

Section through the frame wood of an old window, which like all windows up to the 1950s was painted with linseed oil paint. Even if the care with linseed oil is neglected, the wood has not suffered any damage for decades.

Linseed oil and linseed oil paint have been used for the deep preservation of wooden components for centuries. Wooden components such as half-timbering, folding shutters, doors and especially windows were painted with linseed oil paint, and preserved and cared for with linseed oil until the 1950s. The rule for painters was: "Linseed oil paint is window paint". The original method of producing linseed oil paint consists in rubbing earth colors with the linseed oil binder until a homogeneous color mass is created, whereby the consistency of the color mass changes due to the amount of linseed oil used. Depending on the quality and viscosity of the linseed oil, the user had the option of diluting the color mass with linseed oil, varnish or turpentine oil according to his own ideas. As with the painters, linseed oil paints were made by craftsmen from the 15th century to the middle of the 19th century. “ The newly invented linseed oil paints can be used anywhere, they last forever despite all the hardships of air and sky. “( Leon Battista Alberti : De re aedificatoria. Rom [1452], architectural-theoretical treatise, first publication [1485]; German: Ten books on architecture. Wiss. Buchges., Darmstadt 1991, p. 324. (Unchanged. Reprographischer Nachdr. 1st edition. Heller, Vienna / Leipzig 1912)) Until the mid-1950s, linseed oil paint was produced by the painter himself. Since users and craftsmen today have no influence on the industrially produced linseed oil paint, the knowledge of the craftsmen about the tried and tested composition and modification of pure natural linseed oil paint has also been lost. In the middle of the 20th century, the use of linseed oil paint, especially as a preservative, was still common practice: “ To protect against moisture, the windows must be primed with linseed oil before leaving the workshop. This painting work is generally only to be carried out by the painter so that the oil paint corresponds to the material of the finished paint. “( Richard Bermpohl, Hans Winkelmann : Das Tischlerbuch. Gütersloh 1952, p. 403) From around the middle of the 20th century to around the year 2000, linseed oil paint, with and without solvents, had almost completely disappeared from the trade.

Today's application

For centuries, linseed oil paint was the only proven window paint. Since the 1980s, pure linseed oil paint has been produced again in high quality without thinners or solvents.

In the context of the preservation of monuments, the restoration of the linseed oil preservation and coloring with linseed oil paint on historical windows is an important measure for their authentic repair and maintenance. In window repairs, special emphasis is placed on authentic, traditional, proven substances and traditional craft techniques. Pure linseed oil paints are mainly used in the preservation of monuments and in restoration , as they are based on the historical primer and the linseed oil paints that were common up until the 1950s. Linseed oil paint is not one of many maintenance options in the context of monument preservation, but is even prescribed for the repair of historic windows. Pure linseed oil paints were brought from Sweden to Germany and England by the so-called window craftsmen since 1999. The pure linseed oil paint that is available again opens up the possibility of building on the historical linseed oil paint that has proven itself over 500 years. Parallel to the rediscovery of pure linseed oil paint, the profession of "window craftsman" was developed in Sweden, which is based on the exclusive use of linseed oil paints without solvents or thinners. In the specialist literature and consumer advice, the importance of pure linseed oil paint is assessed differently. According to an assessment from the field of chemical wood protection and wood coating, “pure linseed oil paints (...) no longer play a role in painting in general and in window coatings. If at all, they are only used in the preservation area or offered as so-called organic paints. ” The non-profit association Leinöl im Handwerk eV , on the other hand, points out the historical and current importance of pure linseed oil paints: “ The renewed turn to pure linseed oil paints without solvents was around the year 2000 made possible again in Germany by the fact that with the "window craftsmen", the restorers of historical windows, these high-quality linseed oil products came from Sweden to Germany. "

Quotes

“ ... It is a foregone conclusion that a good coat of oil paint will give the woodwork a longer duration. (...) Good paints and good oil are part of a good coat of paint. A good base and a three coat of paint make a window very durable and this then lasts for a very long time ... “( August Voit : About window frames and their frames then about room doors, house doors, and gates with their fittings in terms of a functional construction and beautiful shape . Augsburg and Leipzig 1829)

" The beauty of painting with oil paint is not based solely on a well-prepared paint, but also in the diligence and effort with which it is applied ... Then the paint must be painted on and off with some effort, which is true every time The coating only becomes very thin, but when the work is repeated often it looks like it is painted. Admittedly, in this way at least two primers and three coats of paint are required, and consequently such work is very valuable, which is why it is usually only strongly primed once and painted twice well. "( David Gilly : Handbook of Land-Building-Art. Braunschweig 1800–1811)

“ In order to improve the brushability, the house painter sometimes thins his colors with turpentine oil; to make the colors appear more shiny, varnishes (copal, amber, dissolved in linseed oil) are used; to make them matt, wax etc. Like. Added. "( Georg Zerr, Robert Rübencamp : Handbuch der Farben-Fabrikation. Textbook of the manufacture, investigation and use of all body colors occurring in practice. Berlin 1922)

literature

  • Leon Battista Alberti: De re aedificatoria. Rome 1452, treatise on architecture theory, first published in 1485; German: Ten books on architecture. Knowledge Buchges., Darmstadt 1991. (Unchanged reprographic reprint of the 1st edition Vienna, Leipzig, 1912)
  • August Voit: About window frames and their frames then about room doors, house doors and gates with their fittings in terms of a functional construction and beautiful shape. Augsburg / Leipzig 1829.
  • David Gilly: Handbook of Land-Construction-Art. Braunschweig 1800–1811.
  • Georg Zerr, Robert Rübencamp: Handbook of color fabrication. Textbook of the manufacture, investigation and use of all body colors occurring in practice. Berlin 1922.
  • Simon Vejbæk Kinch: Traditional paints - linseed oil paints, glue paints and related techniques. KKart Verlag 2013

Individual evidence

  1. ↑ Safety data sheet Linseed oil paint ( Memento of August 12, 2010 in the Internet Archive ) at linoljeprodukter.se.
  2. ↑ Gerd Ziesemann, Martin Krampfer, Heinz Knieriemen: Natural colors. Aarau (Switzerland) 1996, ISBN 3-85502-523-1 , p. 94.
  3. ^ Georg Zerr: Handbook of color production. Berlin 1922, p. 820
  4. ^ Georg Zerr: Handbook of color production. Berlin 1922, p. 821.
  5. ^ Georg Zerr: Handbook of color production. Berlin 1922, p. 832.
  6. ↑ a b c d e linseed oil in handicrafts e. V.
  7. ↑ Association of Swiss Planing Works: Color coatings on wooden surfaces ( Memento from June 26, 2013 in the Internet Archive ) (PDF; 190 kB).
  8. ↑ Kurt Wehlte: Materials and Techniques of Painting. Ravensburg 1985, ISBN 3-473-48350-8 , p. 215.
  9. ↑ Pollutant Lexicon: Aliphatic Hydrocarbons.
  10. ↑ Kurt Wehlte: Materials and Techniques of Painting. Ravensburg 1985, ISBN 3-473-48350-8 , p. 214.
  11. ↑ Erich Kopinski: This is how the painter works. Working techniques of the painting trade. (Series of publications of the industrial union Bau-Steine-Erden). Berlin 1965, p. 64.
  12. ↑ Monica Svederoth: Linolja vid impregnering / konservering av trä (PDF; 1.7 MB), p. 5.
  13. ↑ Erich Kopinski: This is how the painter works. Working techniques of the painting trade. (Series of publications of the industrial union Bau-Steine-Erden). Berlin 1965, p. 65.
  14. ↑ Kurt Wehlte: Materials and Techniques of Painting. Ravensburg 1985, ISBN 3-473-48350-8 , p. 237.
  15. ↑ Kurt Wehlte: Materials and Techniques of Painting. Ravensburg 1985, ISBN 3-473-48350-8 , p. 212.
  16. ↑ linseed oil. In: chromatography-online.org. Retrieved September 10, 2017 .
  17. ↑ Kurt Wehlte: Materials and Techniques of Painting. Ravensburg 1985, ISBN 3-473-48350-8 , p. 237.
  18. ↑ R. Lambourne, T. Strivens: Paint and Surface Coatings. 2nd Edition. Woodhead, 1999, ISBN 1-85573-348-X , pp. 29, 334f. and 369.
  19. ↑ gesetze-im-internet.de: ChemVOCFarbV - Ordinance under chemicals law to limit emissions of volatile organic compounds (VOC) by restricting the placing on the market of solvent-based paints and varnishes
  20. ^ Sonja Allbäck, Hans Allbäck: Windowcraft - Part Two. In: Journal of Architectural Conservation. Volume 10, Number 2, July 2004, p. 8.
  21. ↑ Gerd Ziesemann, Martin Krampfer, Heinz Knieriemen: Natural colors. Aarau (Switzerland) 1996, ISBN 3-85502-523-1 , p. 103.
  22. ↑ Thomas Brock, Michael Groteklaes, Peter Mischke: Textbook of paint technology. Hannover 1998/2000, ISBN 3-87870-569-7 , p. 51.
  23. ↑ Kurt Wehlte: Materials and Techniques of Painting. Ravensburg 1985, ISBN 3-473-48350-8 , p. 244.
  24. ↑ Erich Kopinski: This is how the painter works. Working techniques of the painting trade. (Series of publications of the industrial union Bau-Steine-Erden). Berlin 1965, pp. 66/67
  25. ↑ Robyn Pender, Sophie Godfraind: Practical Building Conservation - Glass and Glazing. Ed .: English Heritage. London 2011, ISBN 978-0-7546-4557-3 , p. 214.
  26. ^ Georg Zerr: Handbook of color production. Berlin 1922, p. 821.
  27. ↑ Harold Speed: Oil Painting Techniques and Materials. London, 1873, p. 217 ff.
  28. ↑ Erich Kopinski: This is how the painter works. Working techniques of the painting trade. (Series of publications of the industrial union Bau-Steine-Erden). Berlin 1965, p. 66.
  29. ↑ Werner Schorlemer: Historical windows and their protection and preservation in the inventory. In: LVR Office for the Preservation of Monuments in the Rhineland (ed.): Working aids for the restoration workshops. Information sheet 5, Cologne 2010.
  30. ↑ die-fensterhandwerker.de: The principles of window restoration .
  31. ↑ Susanne Ruhrländer: Mending instead of replacing? Window craftsman - a new job profile in Sweden. In: glass + frame. Verlaganstalt Handwerk, Düsselberg 2000, p. 44 ff.
  32. ^ State Office for the Preservation of Monuments Hesse: Building consultant window in Hesse. Worksheet I maintenance and supplementation ( Memento from February 2, 2014 in the Internet Archive ). Wiesbaden 2001/2005.
  33. ^ Sonja Allbäck, Bertil Fredlund: Windowcraft - Part One. In: Journal of Architectural Conservation. Volume 10, Number 1, March 2004, p. 56.
  34. ↑ Josef Theo Hein (Dyrup GmbH, WTA) in: Tobias Huckfeldt, Hans-Joachim Wenk (ed.): Wooden windows - construction, damage, renovation, maintenance. Cologne 2009, ISBN 978-3-481-02504-5 , p. 55.