Talk on cleaning acrylic emulsion paints

The ICON Paintings Group invite you to a talk given by

Professor Richard Wolbers
of Winterthur Museum, University of Delaware

Cleaning of Acrylic Emulsion Paints:

Preliminary extractive studies with two commercial acrylic paint
systems using 3D microscopy and liquid chromatography-tandem mass
spectrometry (LC-MS/MS)

Tuesday, 28 June 2011

Doors open at 6pm
Talk begins at 6.30pm prompt

In the Grand Robing Room

at Freemason's Hall,

60 Great Queen Street, London WC2B 5AZ

Close to both Covent Garden and Holborn Tube Stations

Doors open at 6pm

Tickets:
    ICON members UKP10
    Non-members: UKP15

Please register by sending your name and stating if you are an ICON
member Your name must be on the security list no later than Friday,
24 June 2011

Free wine and cheese inc. in price of ticket

RSVP

    Clare Finn
    +44 20 7937 1895
    finnclare<-a t->aol< . >com

There has been a steadily growing body of literature within the
conservation research community specifically designed to evaluate
the impact of solvents including water on both swelling and
extraction of acrylic dispersion paint film used in fine art
applications. Water and other solvent conditions tested thus far on
these acrylic paint films have tended to extract significant,
measurable quantities of paint film components, supporting the idea
that both traditional easel painting aqueous and solvent cleaning
and coating strategies for conserving paintings and painted
artefacts that carry these types of paints will severely compromise
these materials.

To date, only a very limited number of aqueous conditions have been
tested. More concerted data has been needed to fully evaluate the
impact of a wider range of aqueous conditions on these surfaces. To
this end, we've begun a series of experiments specifically designed
to look at pH and conductivity effects of cleaning solutions on
acrylic paints. In the present study, two contemporary commercial
acrylic dispersion paint systems will be evaluated: Golden Acrylic
Colors 'Heavy Body Tube Colors' and ColArt International's 'Liquitex
Acrylic Tube Colors'.

Preliminary results of extraction experiments will be presented.
These will include physical swelling data from a 'matrix' style
application of aqueous solutions to test paint samples. The matrix
used was an 8 x 8 array of triethanolamine /citrate or
ethanolamine/citrate buffered aqueous solutions (50 mM) that vary in
pH 2.5-9.5) and conductivity (principally using NaCl from 0.5-48.0
mS) for a total of 64 distinct application solutions or conditions.

The effects of the application of these 64 solutions will be
presented in two ways. 3D microscopy (Phaseview's MicroPhase Camera)
was used to record volume, surface area, and surface roughness of
the paint samples as they were swollen in time. The MicroPhase
system was used to acquire z-stack images of the paint samples in
standard, uniform-sized paint micro 'dots' (10 micrometre diameter)
utilizing a laser line at 488 nm (ArKr laser, 30 mW) with a 10x Plan
Neofluar (NA 0.3) objective. The resultant 3D images provide
quantitative information about the physical changes that occur in
the test paint samples over the course of 15 min incubations under
the aqueous 'matrix' solutions. The results will be graphically
presented to help illustrate 'high' swelling conditions, as well as
any 'low' swelling aqueous conditions for the test paints.

Additionally, the supernatant solutions were drawn off after 15 min
incubations and analyzed by liquid chromatography-tandem-mass
spectrometry (LC-MS/MS) using a Shimadzu Prominence HPLC interfaced
with an Applied BioSystems 3200 QTRAP. Specifically, the extractable
nonionic surfactant moieties leached into these supernatants were
quantified for each matrix condition. The individual alkyl
phenolethoxylate (APEO) levels were quantified by ESI+ ionization
using [M+NH4]+ precursor ions.

Preliminary experiments on non-ionic surfactants such as Triton
X-305, Triton-405 suggests that ammonium buffered mobile phases are
preferred and MS-MS fragmentation on ammonium adducts appears to
produce the expected ethoxylate and phenol ethoxylate precursor ions
for selective multiple reaction monitoring (MRM) identification of
APEOs with different ethoxylate chain lengths. An ammonium formate
buffered methanol/water mobile phase was used for the reverse phase
C-18 separation of the APEOs with optimized MRM transitions for
individual polymer chain lengths. The use of precursor ion scans was
used to generate criteria for subsequent linear ion trap (LIT) scans
using an information dependent acquisition in Analyst software.
These LIT triggered scans were used to provide a means to identify
degradation or proprietary formulation ingredients in the surface
leachates.


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                  Conservation DistList Instance 24:53
                   Distributed: Monday, May 30, 2011
                       Message Id: cdl-24-53-008
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