PMG Treatment of Crayon Portraits

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Page Information
Date initiated March 2023
Page Compiler Luisa Casella
Contributors Luisa Casella, Lisa Duncan

What are Crayon Portraits?[edit | edit source]

Crayon portraits pose specific treatment issues that warrant a dedicated section of treatment. They can be created by a variety of techniques and can be composed of various materials. They are photographs made by enlargement of a negative often created by photographing a smaller print[1]. Other names for these objects are: solar enlargements; crayon enlargements; solar portraits; solar prints; charcoal portraits; sketch portraits; pastel photographs[1], photo-crayotypes, chromatypes or crayon collotypes[2][3]. Most crayon portraits have applied media - from monotone charcoal drawing over the photographic image to elaborate color application with different media such as oil and can be often be identified as paintings[4][5].

Historical Evolution[edit | edit source]

Liébert Solar enlarger, 1864. Image:
1874 patent by John Barnett for embossing pictures

Crayon portraits spanned in time production from the end of the 19th century to the middle of the 20th century. The first solar enlarger was patented in 1857[1] by David A. Woodward, with major developments in 1864 by D. van Monckhoven and Alphonse Liébert. Liébert created a closed system that allowed transporting the enlarger outside a studio to a rooftop, for example, and was the most common apparatus used in North America. The solar enlargement design likely stemmed from the solar microscope. Alternatively, prints were enlarged using a magic lantern or by placing a short-focus lens camera in front of a light source (window), placing the negative and a diffuser ground glass) on the window, and using the camera lens to project and focus the image onto the light sensitive layer[1]. Solar enlargement became a commercial practice in itself, independent from studio photography[6].

Crayon portraits can be found in a variety of sizes and styles.

Many crayon portraits are heavily overpainted, and many are mistaken for paintings. The quality of this overpainting can vary widely. Often times, only the face is photographic and the remaining portrait is entirely created by the artist applying the color.

These prints are typically on a paper support, that is adhered overall to a secondary board (often domed) or a canvas that is secured to a wooden stretcher.

View of Washington Street, Boston, Mass., December 7, 1899. Photograph by Boston Transit Authority. Credit : Courtesy of Historic New England.
View of Washington Street, Boston, Mass., December 7, 1899. Photograph by Boston Transit Authority.

Types of Portrait Presentation[edit | edit source]

Domed Oval Portraits[edit | edit source]

Domed crayon portraits, often called Convex Portraits, are commonly found in the United States as family heirlooms in private collections.

In 1874 John Barnett filed US Patent 154,576 for Dies for Embossing Pictures[7] that was likely used to produce these. This type of object commonly has a secondary cardboard support.

Portraits on canvas and on strainer[edit | edit source]

Another common form of presentation is to have the paper support of the enlargement adhered overall to a canvas that was then secured onto a strainer.

Domed crayon portrait with applied color. Note the support has been pressed in and torn.

Factors to Consider Concerning Treatment of Crayon Portraits[edit | edit source]

Media[edit | edit source]

Crayon portraits commonly have some type of applied color that could be charcoal, oil and others.

Supports[edit | edit source]

Supports are commonly brittle in these objects and they are prone to damage during handling.

Domed crayon back in raking light.

Types of Deterioration[edit | edit source]

Common forms of deterioration with crayon portraits, especially those with domed supports, are tears and planar distortions.

Treatment[edit | edit source]

The treatment of these may often involve mechanically removing the secondary support. After testing for media solubility, portraits can be washed and relined.

Backing removal[edit | edit source]

Cardboard and canvas backing can typically be mechanically removed using a thin Caselli spatula (larger spatulas can be sanded down to be thinner).

Great caution must be taken as the portrait support is commonly very brittle and easily punctured or torn.

Surface Cleaning[edit | edit source]

Media in crayon portraits is often friable and easily abraded or disturbed. For this reason, surface cleaning of the front should be limited to non abrasive methods such as air bulb. Some larger accretions may be lifted under magnification using fine tweezers.

The media friability also has to be taken into account when placing the object face down to clean the back. In some cases, it is not possible to place the object face down or in contact with any material.

Placing a soft glassing tissue in contact with the front surface when placing the object face down may help prevent any media disruption. When cleaning the back, place a weight or two to prevent the object from dragging which may cause media abrasion.

Back can be clean with soot sponge and soft brushes, taking great care to not erase inscriptions that are common in these objects, and taking into consideration that the support will often be very brittle and easily torn. It is especially important to be careful when cleaning domed crayon portraits, and they should be set onto a shaped book display pillow.

Stain and Discoloration Reduction[edit | edit source]

Test media for solubility to determine if object can be safely washed.

When doing any immersion treatment, start by fixing the media with 5% Paraloid B-72 in toluene[8] or xylene with a spray gun.

Washing[edit | edit source]

Start by misting the object front and back with sprayer with distilled water or by placing in humidification chamber for over an hour. Initial wash should be done in several baths of plain water to remove any readily soluble deterioration products, followed by air drying. If object is very fragile, support with silkscreen mesh screen at ll times (while immersed and to lift from bath). After drying determine if there will be benefit to additional steps.

Light Bleaching[edit | edit source]

Object can be light bleached immersed in water. Follow same steps as for washing (spray or humidify, place in water bath). It is critical to make sure object is fully immersed during light bleaching at all times. Areas that are not immersed will result in mottling, tidelines and other uneven results.

During light bleaching, closely monitor water temperature and it can rise depending on your light setup. If water warms above 70F/ 22C, replace water with cold.

After light bleaching (that can be done over up to 7 hours), rinse object in several water baths to remove any soluble bi-products. Air dry.

Reducing Bleaches[edit | edit source]

Oxidizing Bleaches[edit | edit source]

Chelators[edit | edit source]

Rigid Gels[edit | edit source]

Lining[edit | edit source]

Back of a crayon portrait lined to canvas and secure to a wooden strainer. Image courtesy: West Lake Conservators.

Flat crayon portraits[edit | edit source]

After washing, non-domed crayon portraits can be lined onto a mulberry paper, using wheat starch paste. Lining paper should be the same thickness or thicker than paper support, otherwise object will easily curs or distort.

Drying object in a karibari or using the Dacron lining method prevents the media being under pressure. Tension lining also has the advantage of preventing curling and planar distortion over time that can be observed when crayon portraits are lined and dried in press.

Although one could argue that crayon portraits that were originally lined to canvas and secured to a strainer will become a different type of object when lined to paper, there is no known work or publication by conservators of lining these onto a textile.

Domed crayon portraits[edit | edit source]

Domed crayon portraits with extensive tears may be mended without backing removal but this method may yield unsatisfactory results, with the tears not lining up correctly.

Separating the backing makes it possible to mend the print and backing separately before reattaching them with adhesive.

Current Practices[edit | edit source]

The following current practices were assessed by a 2023 survey posted on the Global Conservation Forum. Treatment of Crayon Portraits Survey Summary:

  • Treatment of Painted Photographs:
    • 87.8% (36 out of 41 respondents) have treated painted photographs.
  • Types of Crayon Portraits Treated:
    • Commonly treated types include Charcoal crayon portraits (85.4%), Crayon portraits with applied pastel (80.5%), Crayon portraits with applied oil (78.0%), Crayon portraits with applied media (unknown composition) (70.7%), Domed crayon portraits (68.3%), Crayon portraits on paper adhered to canvas (68.3%), Crayon portraits on paper adhered to cardboard (**68.3%).
  • Preferred Surface Cleaning Methods:
    • Vacuum (90.2%), Soft brush (85.4%), Eraser crumb (80.5%), Soot sponge (75.6%), Vinyl eraser (70.7%), Air bulb (70.7%) were commonly used tools.
    • Mechanical methods were widely employed for surface cleaning.
  • Methods Used to Remove Crayon Portrait Backings:
    • Direct water misting (75.6%), During washing (70.7%), Poulticing/locally applied moisture from the verso (68.3%) were common methods.
    • Suction table (68.3%), Blotter wash (65.9%), Absorbent non-woven textile wash (63.4%) were often used.
  • Washing Methods:
    • Capillary washing (80.5%), Blotter wash (68.3%), Absorbent non-woven textile wash (65.9%), Suction table (63.4%), Float washing (63.4%) were employed.
    • Overall, washing methods varied based on object sensitivity.
  • Fixative Used Prior to Washing:
    • B72 in xylene (2-5%) (70.7%) was a commonly used fixative.
    • Fixatives such as B72 (70.7%), Aquazol (63.4%), Regal Rez (63.4%) were mentioned.
  • Bleaching Treatments:
    • Light bleaching with artificial light (63.4%), Reducing bleach locally (60.9%), Oxidizing bleach locally (56.1%) were common methods.
  • Methods for Mending or Lining:
    • Tear mending with mulberry paper and wheat starch paste (68.3%) was widely used.
    • Overall lining with mulberry paper and wheat starch paste was a common practice.
  • Inpainting Methods:
    • Watercolors (68.3%), Pastels (65.9%), Color pencil (65.9%), Airbrushing (56.1%) were frequently used for inpainting.
  • Re-stretching onto a Stretcher:
    • Only 2 respondents mentioned re-stretching crayon portraits onto a stretcher.
  • Addressing Support Issues with Domed Crayon Portraits:
    • Using domed glass pieces or creating supports from paper pulp were mentioned.

References[edit | edit source]

Further Reading[edit | edit source]

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