Material Myths, FAQs, and Common Misconceptions from MITRA PART II

materials
myths

(Anthony Waichulis) #1

If it is a “natural” or “organic” product it must be safer, non-toxic, and considered suitable for creating artwork that stable and long-lasting…

False. A similar problem can be noted in our grocery stores, with the rampant use of these terms being used to sell and promote food products. It should never be assumed that these terms are being used responsibly. Today many essential oils (e.g. spike lavender oil, citrus-based, etc.) and soy-based art materials are being marketed using these terms; however, certain individuals may find that these products spur allergic or unpleasant reactions so it is always best to err on the side of caution. In addition, not all of these products are recommended for those who are interested in following best studio practices. For example, some soy-based products are being modified to serve as a replacement for solvents (effectively creating an oil with extremely slow- drying properties). Adding significant amounts of oil with un-saturated fatty acids can lead to the formation of a poor-drying paint film, which can sag, drip, and accumulate dirt and grime over time. Artists are therefore encouraged to exercise due diligence when using “organic” and “natural” art materials.

All pigments/colorants, pastels, pens, markers, colored pencils available today are stable…

False. Realize that lightfastness ratings have been assigned to most available pigments and dyes available today. Generally speaking, certain organic colorants (pigments that tend to only be composed of carbon, hydrogen, and oxygen) and some modern synthetic dyes exhibit a certain propensity for fading when exposed to certain lighting conditions (particularly if UV light is involved). Artists should also note that the binder can play a role in lightfastness (e.g. vermillion has an excellent lightfastness rating in oils and acrylics but is only considered “fair” in watercolor) and the presence of a protective varnish with UV light stabilizers can also help to mitigate color shifts and/or fading. Certain manufacturers may provide information about “permanence” rather than lightfastness, or use proprietary terminology, symbols, and reference scales. Unless specifically started, do not assume that these ratings correlate with ASTM standards. Finally, even if a company lists ASTM ratings (as is done for lightfastness), they may not always be applying the exact protocols outlined in the corresponding ASTM test (e.g. ASTM D4303 for Lightfastness Testing). It is hoped in the future that more companies will begin to conform to the ASTM guidelines in order to help artists become better informed. Please refer to the “ASTM and Lightfastness” document for more information.

Manufacturers of art materials are required to list any and all components present in their products…

False. Companies are only required to list materials if they have been identified as toxic and/or potentially carcinogenic. Safety Data Sheets (SDS or MSDS) will also list the relative amounts of these hazardous components. On the other hand, additives such as fillers, surfactants, semi-drying oils, anti-freezing/anti-fungal agents, emulsifiers, etc. are typically not included on a label unless they are considered toxic. While there is an organization in place (ASTM) that emphasizes the importance of transparency when it comes to listing components in art materials, not all companies abide by ASTM standards. It is hoped in the future that more companies will begin to conform to the ASTM guidelines in order to help artists become better informed. Please refer to the ASTM and Lightfastness of Media document for more information.

I am a better painter than artist X therefore I know more about materials and techniques than artist X…

This argument comes from a place of ignorance and short-sightedness. Many phenomenal painters were poor technicians in terms of preservation strategies and subsequently their works are conservation nightmares.

Turner, Sir Joshua Reynolds, and Albert Pinkham Ryder are just some of the more famous. Conversely, there have been many artists whose works were impeccable constructed using the best materials which offer the world little in terms of artistic vision. While artistic vision, fame, and cultural relevance are completely separate criteria from sound technical practice, these are not mutually exclusive. Generally, the selection of better materials and strategies can allow for similar painterly effects without risking premature deterioration.

If my artwork begins to show signs of degradation it is usually the fault of the materials…

Not necessarily. This is why it is important for artists to accurately document their materials (including information like the date of purchase, particular brand names, etc.) as they continue to work throughout their careers. One way to ensure that this information is kept with your painting is to record your materials and technique on the reverse of your painting (preferably on the stretcher bars or a backing board if the work id executed on a flexible support). There are instances in which signs of degradation can be directly linked to a poorly made product or even a “bad batch” of a material. But unless an artist rigorously documents their technique in a consistent way, it can be difficult to prove that the fault lies with the materials.

Graphite can migrate through the paint layers…

This has become a common misconception amongst artists that can be easily explained. Most paints containing fatty acids (oils, alkyds, and egg tempera) can become more transparent as they age. The predominant effect is caused by the conversion of higher refractive index pigments (such as lead white, zinc white, etc.) into soaps, stearates, and other complexes that have a lower refractive index, and therefore create a more transparent paint layer that eventually exposes the underlying paint layers or underdrawing. In oil paintings, this is further compounded by a slight increase in refractive index that occurs in oil binders over time. This given the optical impression that an underdrawing (done in graphite, for example) is “migrating” to the surface when in fact it is simply a natural chemical change that has occurred in the overlying paint layers. This phenomenon is also associated with the term “pentimenti,” as the increased transparency of the uppermost paint layers can reveal earlier compositional changes and even unrelated paintings or sketches.

Maroger Mediums and Megilp were most certainly used by the Old Masters and have therefore withstood the test of time…

The oil painting mediums proposed by the restorer and painter Jacques Maroger remain a source of interest and at times reverence by some painters, especially those working in the Classical Realist tradition. There is little evidence, however, that any of the mediums proposed by Maroger were ever used by painters commonly called “The Old Masters.” Maroger was obsessed with the idea that a major reason for a perceived decline in painting quality and preservation came not from the breakdown of the workshop traditions of sound painting practice nor from shifting aesthetics, but from the lack of use of some fundamental paint binder or medium. When 21st-century painters mention Maroger mediums they are generally referring to what he termed “Ruben’s Medium” and to a lesser extend “Italian Medium. Maroger had proposed various recipes before his more popular mediums yet even these continued to change after the publication of his 1948 book, The Secret Formulas and Techniques of the Masters . One example, involves an emulsion made by whipping an aqueous solution of gum arabic into inseed oil containing heat dissolved dammar resin. However, it is well known that Dammar, does not appear to have been used to any real extent in Europe before the 19th century and researchers/conservators have never found Flemish oil paintings to be water-sensitive, a characteristic that would have resulted from the extensive incorporation of gum Arabic. Maroger “reconstructed” many mediums but the Rubens and Italian/Venetian still remain by far the most popular among his proponents. Variations of his Rubens Medium all contain mastic resin, linseed oil, and turpentine but differ according to the specific proportions used and whether the mastic and leaded oil components were first dissolved separately and then mixed or were cooked together before straining and then thinning with turpentine. While Maroger mentions treatises and anecdotes to support his theories (often quoting a passage from de Mayerne’s treatise), subsequent research has failed to locate most all of these references. Despite the pronouncements of Maroger’s proponents, formulas relating to his Rubens medium are identical to many recipes for megilp which were commonly used and sold throughout the 18th and 19th centuries. In addition, scientific analysis of the works of Rubens and his contemporaries has found no evidence of these mediums; in fact, their works display a great resilience to the actions of solvents that are typically used to remove discolored varnishes, a charateristic that is not typical for paintings that possess significant additions of varnish in the paint.

Maroger proponents also try to differentiate the Rubens medium from megilp by stating that the latter involves actually boiling the drying oil with lead salts rather than the more moderate heating suggested by Maroger; however, most megilp recipes make no mention of boiling and such claims also ignore the difficulty of precise heating during the Renaissance and Baroque period attributed to Maroger’s mediums.

Maroger’s Italian or Venetian Medium is a mixture of leaded oil and wax. He attributed the impasto of the Venetian Renaissance to the addition of wax. Again no wax has been found in the large number of Venetian paintings that have managed to survive. If significant proportions of wax (at least the quantity suggested by Maroger) were used by these painters, this would have most likely been discovered during restoration campaigns that involved lining; heat from the lining process (almost all paintings from that era have since been lined) would have immediately caused paint layers to melt and become permanently deformed, something that has not been observed. Maroger’s adherents also point to the fact that he was the Technical Director of the Louvre Laboratory and that he tested the works of the Flemish and Italian masters. It needs to be understood that there were no instruments (e.g. chromatography coupled with mass spectrometry) at his

disposal that could confirm the presence of these proposed mediums. While Maroger’s mediums may be pleasant to work with, there is no evidence that they were used by the great masters of the Renaissance and the Baroque. What is well recorded, however, are the disastrous consequences of certain artists who used meglip, including Reynolds, Turner, and many others. Maroger’s influence on artists of the early-mid 20th century and the documented use of his “reconstructed” mediums affords us the chance to evaluate his claims about the effect of his mediums on the preservation of paintings containing them. Artists who continue to paint with the Rubens medium should consider the fact that their paintings will remain sensitive to solvents for years to come. The same is true of paintings created using his Italian Medium, with additions of wax contributing to solvent senstivity as well as heat. Large amounts of resin can also irreversibly darken paint films and even cause embrittlement, leading to severe cracking and loss of paint. Maroger proponents also point to the supposed protective effects of the “black oil” or leaded oil so central to Maroger’s recipes and theories. Dr. Marion Mecklenberg of the Smithsonian Institute’s Museum Conservation Institute, however, has shown that paint films containing even small amounts of leaded oil are substantially weaker than those containing only cold pressed linseed oil.

Those that continue to use Maroger mediums should record the recipe or brand used (as well as the general amount employed) on the back of their paintings so that future conservation efforts can take their presence into account.