completed treatment

VIS. Recto before treatment

VIS. Recto after treatment

Pendant

Pendant before and after treatment by Yara Broekhoff, VIS. Portret van Adriana Eleonora Catarina Hofman van Someren, oil on canvas, 75.5 x 61 x 2.5 cm (unframed), Collection Overijssel, Zwolle, The Netherlands.

  • title Portret van Allard Johan Gansneb genaamd Tengnagel

    artist J. van Hien

    date 1771

    material oil on canvas

    dimensions 76 x 62 x 3 cm

    inventory number P.O.M.00690

    owner Collectie Overijssel

    pendant Portret van Adriana Eleonora Catharina Hofman van Someren

  • wax-resin lining

    surface dirt

    yellowed and crazed varnish layer

    discoloured retouches

    small overpainted areas

  • goal to improve the aesthetical quality and physical condition of the painting so that it can continue to fulfil its historical and commemorative function

    1. surface dirt removal

      Cleaning the painting, using dry and aqueous methods, will safeguard the painting from potential degradation caused by accumulated dirt. The removal will provide a clearer perspective on the present state of the underlying layers and will simplify the varnish removal process.

    2. varnish removal

      The degraded, non-original varnish, having lost its protective and aesthetic functions due to cracks, blanching, and yellowing, will be removed. Moreover, its increasing age makes removal progressively challenging. To minimize the risk of harm to the original paint layers, a solvent gel with minimal polarity and Evolon® tissues will be used for removal.

    3. removal of retouches and overpaint

      The retouches and small area of overpaint in the right shoulder decoration, applied during a previous treatment, are discoloured and cover the original paint. Its removal will improve the aesthetics and physical integrity of the painting.

    4. intermediate varnish

      Applying an intermediate varnish, containing 15% Paraloid B72, will isolate the original paint layers from the retouches. This layer will also enhance the colour saturation of the paint, a crucial step for achieving a colour match between the retouches and the original.

    5. filling and retouching

      To achieve a smooth and even surface for the subsequent retouching, minor losses will be filled. The fills will be retouched to restore unity in both colour and composition.

    6. final varnish

      To protect the paint film from UV light and fluctuations in relative humidity, as well as to enhance colour saturation and establish a uniformly reflective surface, a final layer of varnish, containing 20% Regalrez 1094, will be applied.

    7. Backing board

      To safeguard the canvas from physical forces, dirt, and/or humidity, a backing board will be applied to protect the reverse side of the painting.

    Thorough documentation of both the technical examination findings and the treatment outcomes will be meticulously carried out.

treatment

  • initial condition

    initial condition (VIS)

  • After surface dirt removal

    after surface dirt removal (VIS)

    using a citric acid gel pH 7.5

  • During varnish removal

    during varnish removal (VIS)

    using ethanol and iso-octane (7:3) gelled in 6.5 % ethyl cellulose and Evolon tissues

  • During varnish removal UV

    during varnish removal (UV)

  • After varnish removal

    after varnish removal (VIS)

  • Intermediate varnish layer

    intermediate varnish layer (VIS)

  • before and after filling

    before and after filling

    using Modostuc

  • after retouching

    ↑ before, during, ↓ after retouching

    with Gamblin (Laropal A81) and ethyl lactate

  • final result

    final result (VIS)

highlights

This cross-section was taken for a detailed analysis of the layered structure and composition of the paint.

This process provides valuable insights into the materials used by the artist, the order in which they were applied, and any alterations or restorations that may have occurred over time. By examining cross-sections under a microscope, we can better understand the artist's techniques, make informed decisions regarding restoration, and gain insights into the artwork's ageing and degradation processes.

1 beige ground layer

2 discoloured red lake paint layer

3 red overpaint

4 goldenbrown overpaint

5 varnish layer

microscopic images ↑ visible light, dark field, magnification of 500 ↓ ultraviolet light

An automated thread count relies on image-processing algorithms and machine vision techniques to recognize and count threads from X-ray images of the canvas. The analysis was performed by D.H. Johnson (RICE University).

This process aims to efficiently and accurately assess the fabric's weave density. Thread count analysis can be valuable for dating and understanding the artist's techniques.

The horizontal and vertical thread angle maps on the right show where the tacks held the canvas to the original strainer. This scalloping pattern, called primary cusping, was formed when the canvas was drawn into a peak during stretching. The cusping pattern is uniform, this suggests that the canvas was not made significantly smaller since it was first stretched.

Evolon® tissues and a solvent gel with minimal polarity were used for varnish removal to reduce solvent exposure, solvent penetration, and mechanical action, and to enhance control over the solvent action.

The gel was brushed onto the tissue and cut to the shapes of the composition to avoid tidelines. The tissue was pressed between Melinex® foils for even spreading of the gel. The tissue, placed on the painting with the gel side on the surface, effectively removed most of the varnish after 30 seconds. The remaining varnish was removed with a cotton swab and a free solvent with a lower polarity.

In this image, the extracted tissue is visible, having absorbed the yellowed varnish and also removed some retouches.