Pemulen emulsions for the removal of overpaint, discoloured
remains of lining adhesive, remnants of older varnish layers on a 17th-century
group portrait.
A poster about Pemulen emulsions in conservation, written by
Marjan de Visser and Lucy Odlin part of the pre-printed papers and posters which were then presented at the Gelsin Conservation conference, gels in conservationLondon 16 - 18 October 2017,plus an Appendix by Richard Wolbers 'Terminology and Properties of SelectedGels'. The opening of de Conference was of course by Richard Wolbers. See video.
Introduction
This paper presents a case study of the application of
aqueous gel-based cleaning systems using tailored Pemulen emulsions based on
the Modular Cleaning Program (MCP) developed by Chris Stavroudis.1 Their use is
discussed in the context of the full conservation treatment of a large-scale
group portrait The Archers’ Guild of Middelburg, 1650, by Cornelius Jonson van
Ceulen (1593‒1661).2 The painting (Fig. 1) depicts the Confraternity of St
Sebastian and is displayed in Middelburg town hall in the Netherlands. Notably,
The Archers’ Guild maintains a direct link with the current Confraternity of St
Sebastian. Founded in 1217, the Confraternity remains active today, with 24
current members. These members, passionate about their painting, were the
driving force behind the conservation project. A key stipulation was that the
project should be publicly accessible for the duration of the treatment.
studio view on loketion in Town hall Middelburg 2016 |
Cornelius Jonson van Ceulen and The Archers’ Guild
Cornelius Jonson van Ceulen found success in London as court
painter to Charles I, but following political unrest and dwindling commissions
he returned to his native Netherlands in the 1640s, becoming a member of the
Painter’s Guild in Middelburg where this painting was executed. Set against a
red-brown curtain, the members of the Confraternity surround a table covered
with a red tablecloth, on which various official items are placed. In the upper
left corner there is an aperture with a view to the trees: the turned head of
the concierge, his poised bow, and the archer’s target are just visible. The
curtain displays the coat of arms of the Archers’ Guild, and the open book on
the table details the names of the board members depicted. In the lower left
corner of the tablecloth van Ceulen’s invoice can be made out, bearing his
signature and the date ‘1650’.
Condition before treatment
The large composition was painted on a single piece of
herringbone weave canvas, and had undergone at least two wax-resin linings, in
the 19th and 20th centuries.3 The original tacking margins were no longer
present, and the current tacking margins and front turnover edge were saturated
with a thick sticky layer of yellow-brown wax-resin lining adhesive. Two
distinct types of filling and retouching provided further evidence of at least
two major restorations in the past, increasing the likelihood of varnish and
adhesive residues having been deposited on the surface over time. Throughout
the composition, the degraded natural resin varnish layer had become opaque and
yellowed, dark residues had accumulated in the recesses of the canvas weave and
impasto, and together with a dirty nicotine-like layer they were obscuring the
image beneath.
Methodology and treatment
The conservation treatment was undertaken in a public space.
Free solvent use was minimized and a carbon filter mobile extraction unit was
employed for the health and safety of both conservators and the public. Pemulen
emulsions gels were a suitable option at this point: they are non-volatile and
water-based, can be precisely tailored to the removal of a particular soil, and
their rheological properties can prevent penetration into the paint film beyond
the targeted layer. However initial dirt and varnish removal was carried out
with a buffered solution and free solvents because step-by-step cleaning
provided a better understanding of the surface coatings covering the paint
film.
The degraded varnish and surface coatings masked widespread
discoloured restoration which became more apparent during initial varnish
removal using free solvents, particularly throughout the heavily abraded black
costumes. The sky was overpainted with an opaque blue layer (Fig. 2), which
covered a now ochre-coloured sky. In addition, the discoloured remains of
lining adhesive and remnants of older varnish layers remained across the
painted surface, emphasized by the herringbone weave (Fig. 3). In lighter
passages such as the collars and faces this was considerably disturbing to the
image.
overpaint removal using taiored Pemulen emulsions |
The solubility of the overpaint, remains of lining adhesive
and remnants of older varnish layers was tested using Pemulen emulsions
tailored to different areas following the MCP ingredients and methods. The
mixtures were made up of 1 part Pemulen TR-2 to 1 part water-based mixtures
(v/v), described in more detail below. Water-based mixtures were made up of 5
parts in total (Table 1). All solutions were cleared using petroleum ether.
Results and evaluation
Cleaning tests were evaluated empirically in visible and
ultraviolet (UV) light and using a digital microscope, taking into account the
balance between effectiveness, control and length of application of the
different emulsion mixtures. Pemulen emulsions were applied using white brushes
and agitated for up to 30 seconds, until the clear gel showed signs of
discolouration, and removed with tissue and cotton swabs. This method was
repeated until all residues were removed. Starting with mixtures 1 and 2 and
working across Table 1, the two mixtures were then compared and the most
effective of these was then compared with the next mixture. All stages of the
systematic removal of surface coatings are summarized below.
Surface dirt removal: Nicotine-like surface dirt was
successfully removed using an adjusted water solution buffered to pH 8.5
(bicine +NH4OH), 4.0 mS, cleared with adjusted water pH 8.5, 1.0 mS. A raised
pH was chosen as a first step to break down the degraded natural resin varnish.
Varnish removal: The varnish was removed using free solvent
mixtures of isopropanol and isooctane, and cotton swabs.
Overpaint removal: Black overpaint in the costumes was
removed using Pemulen emulsions gels 4 and 5 depending on the area. Blue
overpaint in the sky was removed using Pemulen emulsions gel 6.
Discoloured remains of lining adhesive and remnants of older
varnish removal: Residues were removed using Pemulen emulsions gels 2 and 4.
Pemulen emulsions at a raised pH of 8.5 and a 10–20% benzyl
alcohol content (emulsions 2, 4 and 5) successfully removed the overpaint and
discoloured residual material. The blue overpaint in the sky, most probably a
lead white oil-based paint, required emulsion mixture 6, containing the lead
chelator EDTA and the surfactant deoxycholic acid.
after treatment |
Conclusion
The conservation of The Archers’ Guild of Middelburg by
Cornelius Jonson van Ceulen posed specific challenges related to the public
location of the treatment. Pemulen emulsions gel system based on the MCP proved
to be a safe and effective method to remove overpaint, remains of lining
adhesive and remnants of older varnish layers from a 17th-century painting.
Notes
For an initial bibliography see
www.getty.edu/conservation/publications_resources/teaching/caps_modular_cleaning.pdf.
MCP software can be downloaded from
cool.conservation-us.org/byauth/stavroudis/mcp/. For an introduction to aqueous
gel cleaning methods see also Stavroudis and Wolbers 2012.
The name ‘Cornelius Jonson van Ceulen’ is how the artist
referred to himself when he moved to the Netherlands, rather than ‘Cornelius
Johnson’ as he is known in the UK.
In the 19th century a lining was also carried out to repair
tears in both lower corners, and more recently in the mid-20th century, to
address a large tear in the centre of the composition.
Reference
Stavroudis, C. and Wolbers, R. 2012. ‘Aqueous methods for
the cleaning of paintings’, in J.H. Stoner and R. Rushfield (eds), The
Conservation of Easel Paintings. London and New York: Routledge, 500‒523.
Authors’ addresses
Marjan de Visser, Restauratieatelier Marjan de Visser, Den
Haag, The Netherlands (marjan.de.visser@restauratieatelier.com)
Lucy Odlin, Paintings Conservator, London, UK
for detailed recepis please contact Marjan de Visser
Geen opmerkingen:
Een reactie posten