Recap Gels In Conservation Conference 6 of 6

The London Gels in Conservation Conference: An IntroductionWritten by Jodie Utter, Senior Conservator of Works on Paper, Amon Carter Museum of American Art.

Michelle Sullivan, “Rigid polysaccharide gels for paper conservation: a residue study”

This blog post is part of a series of observations about the London “Gels in Conservation” conference co-hosted by the Tate and IAP (International Academic Projects, Ltd). In mid-October, over the course of three days, some 41 authors presented research, techniques and ideas on gels in conservation. The talks were excellent, and I’ve focused on four that were notable for the wide range of materials treated and challenges faced. They ranged from coating/grime removal from a giant sequoia tree cross section, to dirt and varnish removal from Delacroix wall paintings, to removal of repairs from a fragile felt hat from a 18th century ship wreck, and an experiment comparing residues left behind by various gels on paper.

                             

Research Question

The fourth talk I wanted to highlight is Michelle Sullivan’s “Rigid polysaccharide gels for paper conservation: a residue study” -- of particular interest to me as a paper conservator. It was one of the few studies exploring quantitatively if residue is left behind by gels used in the treatment of works on paper. If so, did how does that residue impact the paper? To easily track residue on the paper samples, fluorescein dyes visible in UV light were added to the gels tested. The experiment used agarose, gellan gum and methyl cellulose gels in three different concentrations applied to three different papers for three different time periods. In addition, a few variables were added to mimic treatment, such as applying the gels through Japanese paper and clearing the gels using a damp swab. Besides surface examination, cross sections of the samples were also taken to see if the gels were penetrating the paper surface. The cross sections seemed to suggest that gellan gum was being absorbed into the paper. Sullivan found that all the gels tested left a residue, with gellan gum apparently leaving behind the most. She found that applying the gels through a Japanese paper barrier was the most effective method in minimizing residue. After oven aging for 21 days, the rag sample treated with gellan gum darkened slightly, while all the other samples did not. Sullivan proposed that the darkening might be related to the gelatin content of the rag test paper. She plans to expand her test variables and continue to build on this research. This feels like very important research and I eagerly await to results of the next phase of her work.

                                     

Residue Experiment set-up

This blog series is a result of receiving the FAIC Carolyn Horton grant to help me attend the conference. I would like to gratefully acknowledge the FAIC for helping make it possible for me to attend this important conference.

Recap Gels In Conservation Conference 5 of 6

The London Gels in Conservation Conference: An IntroductionWritten by Jodie Utter, Senior Conservator of Works on Paper, Amon Carter Museum of American Art.

Jonathan Clark, “Revisiting a shipwrecked felt hat for Chatham Historic Dockyard Trust: a multidisciplinary approach”
This blog post is part five of six in a series of observations about the London “Gels in Conservation” conference co-hosted by the Tate and IAP (International Academic Projects, Ltd). In mid-October, over the course of three days, some 41 authors presented research, techniques and ideas on gels in conservation. The talks were excellent, and I’ve focused on four that were notable for the wide range of materials treated and challenges faced. They ranged from coating/grime removal from a giant sequoia tree cross section, to dirt and varnish removal from Delacroix wall paintings, to removal of repairs from a fragile felt hat from a 18th century shipwreck, and an experiment comparing residues left behind by various gels on paper.

Image of felt hat during treatment

Jonathan Clark’s presentation, “Revisiting a shipwrecked felt hat for Chatham Historic Dockyard Trust: a multidisciplinary approach” featured a really cool felt hat from a 1758 shipwreck. The project resulted in an unusual opportunity for collaboration between a textile and an objects conservator--both bringing needed experience to successfully treat the hat. In the past, the object had been treated aggressively with layers of synthetic materials and heavy cardboard fills. The hat was misshapen as a result of the thick repairs, making it difficult to fully see the original object. The treatment objective was to release the fragile felt hat from its past repairs and reshape it to its intended form without harming the object. Acetone softened the thick unknown adhesive, so both acetone vapor and solvent gels were used to release and reduce the adhesive. The acetone solvent gel was applied through spider tissue, a very soft and strong paper (100% manila fibers). Once in place, the spider tissue was pre-wetted with methylated spirits, then the gel was applied via spatula, which was then covered with plastic wrap to slow evaporation. Once the old repairs were removed the hat remained misshapen, to further soften the remaining adhesive holding the felt hat out of shape, it was placed in an acetone vapor environment. The softened pliable hat was then weighted and pinned to a Fosshape form, a shrinkable polyester felt, used by textile conservators to create mounts. The end result was an object that was stable and could safely be stored showing only its original materials.

                                              

Felt Hat after treatment

This blog series is a result of receiving the FAIC Carolyn Horton grant to help me attend the conference. I would like to gratefully acknowledge the FAIC for helping make it possible for me to attend this important conference.

Recap Gels In Conservation Conference 4 of 6

The London Gels in Conservation Conference: An Introduction

Written by Jodie Utter, Senior Conservator of Works on Paper, Amon Carter Museum of American Art.

Alina Moskalik-Detalle, “Conservation of murals by Eugene Delacroix at Saint Sulpice, Paris”

This blog post is part four of six in a series of observations about the London “Gels in Conservation” conference co-hosted by the Tate and IAP (International Academic Projects, Ltd). In mid-October, over the course of three days, some 41 authors presented research, techniques and ideas on gels in conservation. The talks were excellent, and I’ve focused on four that were notable for the wide range of materials treated and challenges faced. They ranged from coating/grime removal from a giant sequoia tree cross section, to dirt and varnish removal from Delacroix wall paintings, to removal of repairs from a fragile felt hat from a 18th century shipwreck, and an experiment comparing residues left behind by various gels on paper.

                              

Alina Moskalik-Detalle talking describing coating removal

In the second of four talks, Alina Moskalik-Detalle presented “Conservation of murals by Eugene Delacroix at Saint Sulpice, Paris.” The talk was interesting for its scale and challenges. Because I’ve gone to see these murals many times over the years, the talk was also personally interesting. Each time I visited, I left somewhat disappointed by the darkened, flat, dull murals. As luck would have it, I was scheduled to travel to Paris a week after attending the gels conference. What I saw when I visited Ste. Sulpice was truly remarkable—color, depth, and drama. The cleaning had totally transformed these murals. Naturally, I couldn’t help myself, I actively looked for shiny patches—the results from this treatment were remarkable. This multi-year project involved numerous conservators including collaboration with Richard Wolbers. Some of the treatment challenges included flaking paint, complex paint layers, multiple restorations, rising damp in the walls, carbon based grime, and, if that wasn’t enough, the paint was very sensitive to organic solvents. The conservators wanted to limit penetration of their solvent gels without leaving a residue or tide line behind. They wanted good contact between the gels and the substrate, control of the action of water, and to create mixtures of solvents that would clean effectively without damaging the paint layers. After cleaning tests were performed, a treatment protocol emerged: by pre-saturation of the areas being treated with cyclomethicone followed by the application of silicone solvents gels to the mural’s surfaces, tide lines were avoided, grime could be removed, the gels could be cleared, and residue was limited. The D4 was a slow evaporator which allowed about a 30 minute working time for the application of the gel and subsequent grime removal without harming the paint layer.

                                                

Delacroix mural detail, during treatment

The gels were made and applied in a paste-like consistency for maximum control of where the material was placed. It clung to the vertical walls and horizontal ceiling long enough to be effective. Using D4 based emulsions to clean the mural’s paint surfaces allowed the removal of surface soil without stripping wax or oily components from the paint films themselves. Because the emulsions were surfactant free, it was easier to clear them from the treated surfaces. Analysis of samples didn’t show residue left behind on the surface, but when the conservators tried to consolidate flaking areas of paint, they had trouble with adhesion, it is unclear why. It will be interesting to see how these murals age over time and if further treatment is needed in future, how re-treatable it is.

                                            

After treatment

This blog series is a result of receiving the FAIC Carolyn Horton grant to help me attend the conference. I would like to gratefully acknowledge the FAIC for helping make it possible for me to attend this important conference.

Recap Gels In Conservation Conference 3 of 6

The London Gels in Conservation Conference: An Introduction
Written by Jodie Utter, Senior Conservator of Works on Paper, Amon Carter Museum of American Art.

Lu Allington-Jones, “Giant sequoia: an extraordinary case study involving Carbopol gel”

This blog post is part three of six in a series of observations about the London “Gels in Conservation” conference co-hosted by the Tate and IAP (International Academic Projects, Ltd). In mid-October, over the course of three days, some 41 authors presented research, techniques and ideas on gels in conservation. The talks were excellent, and I’ve focused on four that were notable for the wide range of materials treated and challenges faced. They ranged from coating/grime removal from a giant sequoia tree cross section, to dirt and varnish removal from Delacroix wall paintings, to removal of repairs from a fragile felt hat from a 18th century shipwreck, and an experiment comparing residues left behind by various gels on paper. 

                         

Image of cross section in upper gallery 

The first session of four, “Giant sequoia: an extraordinary case study involving Carbopol gel”, was presented by Lu Allington-Jones and was intriguing for several reasons: the object was enormous--5 meters (over 16 feet) in diameter. The size alone produced significant challenges, for which solvent gel was particularly suited. The scale meant that it would be treated in situ in full view of the public, thus potentially exposing patrons to chemical fumes; it would require large amounts of materials to treat; and it was at the top of an open staircase, meaning significant height came into play, as well. The giant sequoia cross-section had been on continual display since 1894, so it was incredibly dusty, had a darkened and cracking lacquer coating, and had a very friable bark around its perimeter. A material was needed that could safely remove the failed coatings and accumulated dust without penetrating the surface, harming the friable bark, or creating an unsafe environment for the conservators and patrons during treatment. Using a solvent gel had the advantage of keeping the solvents contained, reducing solvent vapor, and could act as a poultice to reduce grime and solubilize the failed coating. In addition, because gel ensures contact with the treated surface, it means that a lower concentration of solvent could be used as compared to a free liquid solvent. The gel was made 24 hours ahead in Ziploc baggies, the time allowed the gel to reach the needed smoothness and viscosity. 

Gel application and removal images 

For application, the Ziploc bags were cut open at one end, the gel squeezed out and spread to 20 mm thick (about ¾”), then covered with plastic wrap to slow evaporation, giving the conservator about an hour of working time before the gel became too sticky and unworkable. Once the gel softened the coating, it was then removed trowel-like with a piece of cardboard, repeated, then cleared with industrial methylated spirits and wipes. A significant lesson learned about the gel was once it reached 73F or more, it became runny, causing the gel to slip off the vertical surfaces being treated, which didn’t allow enough working time to reduce the surface coating adequately. Once treated, the cross section was varnished with a protective layer of Laropal A81. The cross section looked amazing in the after images. I would encourage everyone to read the article in the post prints as it describes the details of challenges, decision making, and final outcomes.

This blog series is a result of receiving the FAIC Carolyn Horton grant to help me attend the conference. I would like to gratefully acknowledge the FAIC for helping make it possible for me to attend this important conference.

Speaker Series at Heritage Auctions

Join us this coming Monday, March 5th as Heritage Auctions hosts one of their insightful Art and Design Speaker Series. This time Laura Hartman, Associate Paintings Conservator at the Dallas Museum of Art will be talking about art conservation.

This event is a wonderful opportunity to hear Laura talk about her experiences in art conservation and at the DMA.


ART MEETS SCIENCE: CONSERVATION AT
THE DALLAS MUSEUM OF ART
March 5 at 6:00 pm

HERITAGE AUCTIONS
Design District Showroom
1518 Slocum Street
Dallas, TX 75207

SPACE FOR THE LECTURE IS LIMITED
Kindly RSVP to
RSVP@HA.com
or 214.409.1050

See you there,

Brad

Recap Gels In Conservation Conference 2 of 6

The London Gels in Conservation Conference: An Introduction 
Written by Jodie Utter, Senior Conservator of Works on Paper, Amon Carter Museum of American Art.

Richard Wolbers and Paolo Cremonesi
This blog post is the 2nd in a collection of observations about the London “Gels in Conservation” conference co-hosted by the Tate and IAP (International Academic Projects, Ltd). In mid-October, over the course of three days, some 41 authors presented research, techniques and ideas on gels in conservation. The first presentations of the first day kicked off the conference, setting the tone with intriguing philosophical, as well as practical hands-on examples of gels in conservation. The two leading conservation scientists in the field of gels, Richard Wolbers and Paolo Cremonesi, each provided an introduction to gels in conservation, what has been done historically, what is currently practiced, and thoughts for the future. Wolbers not only delivered the key note presentation, but spoke several times as collaborator for many of the talks and as a moderator. In his keynote address, Wolbers emphasized minimizing toxicity through substitution of less toxic materials and Cremonesi discussed the characteristics of agar gels and the current work being done with thermo-reversible rigid agar hydrogels.

Bottom line, it seems that the basic goal for many of the case studies that were presented is to find a way to safely use aqueous cleaning systems on water-sensitive materials without damaging the object. A tall order. 

Wolbers’ talk, “Gels, Green Chemistry, Gurus and Guides, provided an overview of gels in conservation, as well as a look towards the future”, emphasized the goal of using Green chemistry, which involves less waste and is less toxic - something he has been advocating for years (here is the link to his talk: https://www.youtube.com/watch?v=RGpOYaU6owE).

Wolbers said, when confronted with a treatment problem, first determine if a gel is appropriate. Gels keep the gel and its contents in contact longer with the surface; gels make local application controllable or they can serve as a poultice. Naturally, the gel used shouldn’t impact the surface medium, and it should be non-toxic and clean the object. Wolbers listed some of the advantages of solid rigid agar gels: they dissolve in water, improve surface wettability, and have surfactant properties.

Ultimately, to do the best by our objects, we as a field need to continually look to other industries for ideas. For example, the cosmetic industry utilizes green chemistry to reduce exposure to potentially harmful solvents. We need to truly understand what we want to achieve in a particular circumstance and tailor it to our object, rather than relying on a few stock recipes and applying them to all situations. As conservators we must remain agile and stay creative. To do this we must understand the underlying principles of the materials we want to use and the objects we are treating. Conservation needs to be able to gain ideas and experience from other fields, and also be able to create and engineer our own materials to give us the type of control we need. 



In Cremonesi’s talk, “Thermo-reversible rigid agar hydrogels: their properties and action in cleaning”, (here is the link to Cremonesi’s talk, https://www.youtube.com/watch?time_continue=10&v=UbbxCQR4El8) he listed the advantages of agar gels: how they dissolve in water, and improve surface wettability. They have limited adhesion to the surface and, most importantly, leave behind minimal residue (as compared to gellan gum. (See M. Sullivan’s paper “Rigid polysaccharide gels for paper conservation: a residue study”). Past drawbacks of agar gels had been that they could only be applied to relatively flat surfaces. However, if the liquid gel is applied (brushed or poured on) just at the moment it starts to thicken, it can be used on a variety of surfaces, planar or not.

(here is the link to his talk: http://academicprojects.co.uk/gels-conference/gels-conference-presentations/)

Thermo-reversible gels are often prepared in the microwave to prepare a homogeneous gel. When heated above 80F (Cremonesi recommended type E for its low gelling temperature) the gel is liquid and when cooled below 80F it is a solid. With increased concentration, the gel becomes stiffer which will slow the release of water from the gel. While in the liquid form it can be poured into receptacles such as a syringe body. Allowed to cool, once solid it can be kept in a “pencil” shape (this slide caused many audience members to swoon) or be cut into small plugs.



At room temperature it can also be grated, with the shaving manipulated for surface cleaning. Enzymes mixed with Agar in a semi-solid state are the most effective form of the material. That said, Cremonesi said gellan gum is more appropriate for works on paper because it’s more flexible and transparent than agar.

One thing I’ve found with using gels (in my case gellan gum) is the formation of tide lines, which made me assume we were doing something wrong. According to both Wolbers and Cremonesi, I was missing a step. They talked about the importance of pre-wetting the surface to be treated with a non-polar solvent (they specifically mentioned D5, aka decamethylcyclopentasiloxane aka cyclomethicone). At first this might seem counter-intuitive: how does water work if there's non-polar solvent in the way? Actually it’s about displacement - oil floats on water – so the water in the gel displaces the non-polar solvent to get to the surface. The non-polar solvent prevents tidelines principally by blocking capillarity. Now it’s all starting to make sense. The same principle was used by Burgio, Rivers et al (2008, Studies in Conservation) when consolidating matte paint. On this basis, any non-polar solvent (first spot tested) should work to prevent tidelines. D5 has the advantage of being a ‘green’ solvent, comes without the H&S hazards associated with hydrocarbon non-polar solvents, and is exceptionally non-polar.

This blog series is a result of receiving the FAIC Carolyn Horton grant to help me attend the conference. I would like to gratefully acknowledge the FAIC for helping make it possible for me to attend this important conference.