Transcript of the video "Treatment of the Marseille Petticoat"
Video length: 00:16:07
Season Tse, Senior Conservation Scientist
When Chris first contacted me about coming to CCI to do a treatment on this very rare piece of 18th century textile, I was quite enthusiastic.
[Details of brownish stains on off-white embroidered petticoat.]
The textile in its original state is not able to be exhibited because of the stain and is very disfiguring and it's distracting from the viewer.
Most textiles cannot be subjected to stain reduction treatments. But this particular textile is unique, in that it is first of all white: if it has color or embroidery then it would not be suitable for stain reduction treatment that we have planned for.
And also it is very robust if it was fragile or brittle in any way we will not be considering the treatment that we had planned.
Based on initial images we thought that the stain contained iron because it was kind of orange. So we have planned that if it was iron then we would need to use a combination of dithionite and EDTA solution in order to reduce and remove the iron ions.
[A conservator is spraying sodium borohydride solution on petticoat.]
Further stain removal would require the use of sodium borohydride. Borohydride has many benefits: as a reducing agent it is able to reduce the discoloration and also reverses some of the effects of aging. And also it is alkaline and it would be able to reduce the acidity of the textile as most historic textiles are acidic.
[Chris Paulocik is using the end of a vacuum hose to remove soiling from the petticoat.]
In addition to Chris's extensive experience in textiles we also need a team of conservators and scientists at CCI in order for this treatment to be carried out successfully.
[Conservators and scientist sitting at a conference table discussing the petticoat. There are various pictures of the stains in front of them.]
As a scientist I have the knowledge on research and also experience on using these chemicals and their effect on textiles.
[Close up of conservators Renée Dancause, Janet Wagner, and intern Michelle Hunter]
But in addition we need the textile conservators in the textile lab Renée Dancause, Janet Wagner, and our intern Michelle Hunter they are all knowledgeable and experienced with treating and handling historic textiles and they know and are very familiar with large textiles and their vulnerabilities.
[Close up of Crystal Maitland]
Our paper conservator Crystal Maitland is experienced in using treatments for stain reduction on paper but she's also experienced in using gels to further remove stains.
When we first saw the textile we were quite surprised as to how much worse it looked in real life than from the photos. So we got together and we did spot testing of the stained areas and it was quite alarming.
[Season Tse doing spot testing of petticoat using pH strips. She then demonstrates how low the pH level is by comparing the results to a color-coded chart.]
The pH of the darkly stained area some were as low as ph3 which means that it is extremely acidic. If left untreated those areas the time is going to deteriorate and become brittle and it will destroy the textile in the long run.
The x-ray fluorescence analysis showed us that the area that is heavily stained contains iron, but so does the rest of the piece of textile, it has a low level of iron all across the piece of textile.
[Detail of an X-ray fluorescence spectrometer being used on a section of the petticoat.]
Because the stained area does not have a higher concentration of iron we felt that the stain is not caused by iron.
Our spot tests also show that by adding a small amount of detergent in the water the stain becomes soluble much faster and much more readily. As a result of these spot testing and the analysis we plan the following course of treatment:
First we will use a low concentration of an anionic detergent Orvus in this case 0.1 percent and we're going to immerse it and remove as much as the surface dirt and as much as the soluble discoloured material as possible with the detergent wash.
[The detergent solution is being poured into a large wash tank. The petticoat is then immersed in the large bath by a team of conservators.]
We rinse it as many times as we need to remove the detergent residues and then following that we're going to try to use gellan gum to see if we could further reduce the staining.
[Conservators use sponges to facilitate dirt removal in the wash bath. Further stain removal was desired, so gellan gum, dithionite and EDTA as well as sodium borohydride were tried.
After that we will use dithionite in combination with EDTA to remove any harmful metal ions that is in the textile and followed by rinsing. The final step if we need to we will use the sodium borohydride to remove the remaining stain to brighten the textile, the heavily stained area we're going to use a higher concentration of sodium borohydride solution in order to reduce the stain as much as possible.
Before the wet cleaning of the petticoat a few preparations needed to be undertaken. The first step was to stabilize some of the loose elements to protect them during wet cleaning.
[Conservators secure raw fabric edges and other vulnerable areas of the petticoat by stitching temporary polyester fabric reinforcement in place using polyester thread.]
The petticoat has two vertical pocket slits and an unfinished waist edge. To protect these areas we placed a sheer polyester fabric over them and temporarily stitched them into place using polyester threads. The next step was to mechanically remove the accretions and loose particulate soiling on the surface of the textile.
[Under magnification, a conservator uses fine tweezers to remove brown-coloured accretions. Overall loose soiling is removed using a vacuum on low suction]
The accretions were gently removed using tweezers under microscopy. The loose particulate soiling was removed by gently vacuuming the textile using low suction. To assist with wet cleaning treatment we used a conservation grade surfactant. This surfactant was prepared by dissolving it in water and stirring it to ensure it was fully dissolved.
Renée Dancause, Conservator Textiles
The petticoat is quite large and so we assembled a large stainless steel wash tank for the wet cleaning treatment. So it enables us to wet clean a petticoat in about an inch of water we don't want to use any more water than is necessary.
[Conservator is filling a large wash tank with about an inch of water. The team then lays the petticoat flat supported on a nylon screen in the wash tank.]
The petticoat will lay flat in the wash tank.
We also have assembled a small plastic wash bin, and that will be used in the fume hood because it's necessary for the sodium dithionite treatment which is quite smelly, and a smaller wash tank or wash tub was necessary to use in the fume hood.
Janet Wagner, Conservator, Textiles
We just completed the first step in the wet cleaning process. We filled the tank with the reverse osmosis water from the textile lab supply. And in the end we filled the tank with about an inch of water which was about 90 liters of water and that was enough to cover the textile while it was in the wash tank. We then added the prepared surfactant into the wash bath into those 90 liters of water and we just evenly distributed the surfactant in the bath just using our hands.
[The wash tank is filled with about an inch of water. The surfactant is added then evenly distributed in the water. The petticoat is folded, placed on a nylon screen and added to the water].
Due to the size and weight of the petticoat we had to pre fold it and we placed it on the nylon screen. So we placed the screen with the petticoat on top into the wash tank and then we unfolded the screen in the wash tank which filled the whole wash tank and then we slowly unfolded the petticoat.
[The petticoat was sponged, paying particular attention to the stained areas.]
We then wet out our natural sponges and we gently sponged the petticoat to loosen the dirt, focusing on the stained areas. So we did that…Several people did that and we gently sponged for a number of minutes. We then floated the textile in the water to turn it over so that we could gently sponge the other side. We took samples of the water at this point just to determine what the discoloration was and how much dirt was coming out of the textile and if indeed another wash bath was warranted. And it was determined that it was not, that the discoloration was not that much and we would not do another bath with surfactant. So then at that point then we floated the textile again in the bath and we folded it into a smaller area so that it can be removed from the wash tank. And the screen was also folded so it could be lifted out with two people out of the wash tank onto a supporting table. We then emptied the tank with the aid of portable pumps and we also had to tilt the table at some point to get more water out and also use squeegees to get the water out so that we can prepare the tank for the rinse.
Season Tse narrates
After the surfactant bath the petticoat was rinsed a number of times in reverse osmosis water until all the surfactant has been rinsed out.
Crystal Maitland, Conservator, Paper
So as a final stage of washing we moved the textile out of the baths and onto a table blotting it dry with a toweling to damp dry and then we tried gellan gum for the highly stained areas of the textile.
[The Petticoat is carried by the team of conservators to a large table. The textile is blotted with white towels. Gellan gum is pressed down onto the stained areas.]
Gellan gum is a high molecular weight polysaccharide, it’s a natural biopolymer that gels at really low concentrations in water.
And it's used in conservation to deliver aqueous chemistry to the surface of artifacts, it helps control the spread of moisture or can increase the dwell time on a surface and it also has a small amount of capillary pull that can help pull degradation products or soiling off of the surface or out of objects. Low acyl gellan gum has been explored extensively for paper conservation and it's a relatively transparent rigid gel that is surface conformable enough for a paper and ink surface. But textiles are inherently more three-dimensional on a micro scale, from the twist of the thread to the weave of a fabric to, in the case of this textile, the dimensionality of the embroidery. We needed a more conformal gel. Fortunately there's a second type of gellan gum called high acyl gellan gum. It's much more drapable and unfortunately is not transparent.
[Conservators ensure a good contact between gellan gum and petticoat by application of hand pressure.]
It’s however harder to prepare at higher concentrations and so by mixing the two low acyl and high acyl polymers we can get aspects of each: the transparency and easy preparation of the low acyl gel and the surface conformability of the high acyl gel. To make the gels you have to heat a solution to a molten state we use a microwave and then to set the gels you just pour them out into a container of your choice and let them cool. Formulations are a balancing act, we want a higher concentration to have smaller pores and more capillary pull but we want the drape-ability that we get at a lower concentration. So by adding in high acyl we get the drape with a higher concentration that we can pull from the low acyl gel.
[Gellan gum is cut to size by conservator. The gel is placed on the petticoat with weights on its surface.]
We left the gels in contact with the surface of the textile for about an hour and in this case we didn't see a lot of pull of discoloration products into the gel. We did achieve good surface conformability that we were looking for and will continue to investigate the use of these gels in future conservation treatments.
Season Tse, Senior Conservation Scientist
After the application of gellan gum we used two reducing agents separately: sodium dithionite and sodium borohydride.
[Conservation scientist mixing sodium dithionite and EDTA with water in a plastic bin.
We choose these reagents because not only are they able to reduce stains, they are also not damaging to the textile. In fact they have a stabilizing effect on the textile. We use sodium dithionite with EDTA to remove any harmful metal ions that are in the textile and because the reagent is very smelly we used it in the fume hood.
[The petticoat is placed on a screen and immersed in the solution.]
We immersed the textile in 2% dithionite EDTA bath for about 30 minutes. The textile looked brighter as a result of it the dark stains were slightly reduced but they were still very prominent. After rinsing in reverse osmosis water we decided that we need to immerse the textile in the sodium borohydride bath. So we immersed it in a low concentration of sodium borohydride for 30 minutes there were a lot of bubbles formed from the textiles because of the hydrogen gas produced as borohydride react with the acids in the textile.
[Conservators apply a higher concentration of sodium borohydride solution to persistent stains using spray bottles and brushes, then cover the reducing agent with Mylar sheets to prolong the chemical reaction.]
After 30 minutes of immersion in the low concentration borohydride solution we removed the textile and placed it in the wash tank and we applied a higher concentration of borohydride locally in the darkly stained areas. We also covered it with Mylar so that it would prolong the effect of the reagent.
After we felt that there was no more improvement of the color reduction we ended the treatment and we immersed the textile in reverse osmosis water and to rinse out all the residue of the borohydride.
After the treatment the level of acidity has been much reduced, harmful metal ions and oxidized products have been removed. The textile’s much more stable from a chemical point of view. From an aesthetic point of view the heavily stained area have been much reduced and the lighter water stains have been mostly reduced. The overall appearance of the petticoat is much brighter, the delicate and refined needle works with a subtle but elaborate pattern is now visible without distraction.
Renée Dancause, Conservator Textiles
So the petticoat was blotted with many clean white towels in order to damp dry it. And the thing to remember about wet cleaned textiles is that we like to dry them fairly quickly.
[The conservators place a large mesh screen frame on a table. The screen is raised using foam blocks.]
This textile is very particular in that it's two layers and each of the layers is composed of three layers of textiles. So we needed to create air circulation in order to speed the drying process.
The textile was placed on raised support screen and it was raised by using blocks to allow air to circulate underneath the screen and around the petticoat. We separated the two layers of the petticoat in order to provide more air circulation and we did this by bunching up some nylon tulle fabric inside the petticoat. Next we used some very large floor fans to direct some airflow around the petticoat and we also used handheld dryers on cool settings just to accelerate the drying process. It took over an hour of concerted effort with the handheld dryers on a cool setting to dry the petticoat partially. We will leave the petticoat to dry in the open air in the lab overnight.
[A before and after comparison of the petticoat textile is shown. The large stain appears fainter and the fabric appears cleaner and brighter after the treatment.]
This video explains in detail, the treatment process to improve the visual aspects of an 18th century textile as well as the condition of the textile itself. This video was created by the Canadian Conservation Institute.