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Treatment
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22 Feb 2017
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Remove previous conservation and make safe for in-house display and storage.
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Organics
- Reason
- Permanent Exhibition
- Description
- Treatment
pH Tests (taken with pH indicated papers)
pH of de-ionised water: 7.27
pH of de-ionised water + samples
• Fibre debris below fringe: pH 5.04
• Impregnated (PVA) fibres from exposed edges of previous treatment on upper edge, proper left side, 410mm from corner: pH 6.78
• Section of previously washed fibres found nesting on surface of loose waeve proper left side: pH 5.85
• Brown dyed fibres on proper left side: pH 6.49
• Iron stain, central front: pH 5.95
The fibres level of acidity of the fibres was considered acceptable, and in fact were not as acidic as expected. This is probably because the cloak was washed in the previous conservation treatment in the 1960s, which would have removed much acidic degradation products. No further de-acidification (if at all possible) was considered necessary.
Iron tests
Indicator paper for iron ions from PEL (Preservation Equipment Ltd) was used.
The dark stains on the central front of the cloak and also where previous nail(?) holes were located were tested for iron.
Results (a magenta colourant appearing on the paper) indicated Fe2 ions were present on these stains.
No iron ions were detected in the dyed brown section, or undyed cedar bark.
Removal of the support net
While the net treatment has no doubt held the very fragile robe together for over 50 years, the treatment is now considered inappropriate. It completely covers the reverse of the robe thus preventing any study of the back. Also, areas of the white net are visible from the front, which highlights rather than reduces the visual impact of the damage. The amount of net applied provides an unnecessary amount of support, as well as an uneven amount of support - there are sections of the net that are not adhered to the object. Also, the excessive amount of adhesive used to apply the net can be seen as shiny patches on the reverse. In addition, the consolidant is not removable, which makes re-alignment of certain areas not possible.
Spot tests on net: Based on previous treatments in the studio on similar objects, a sepiolite poulticing method was considered. This would allow controlled softening of the adhesive in specific areas, avoiding solubilising it and driving it further into the fibres. Tests were carried out to determine what solvent / solvent combination was most effective.
Acetone was found to soften the adhesive to allow separation of netting. However the adhesive became very sticky and appeared to be stronger than the fibres, thus making it too difficult to remove from the impregnated fibres without causing further damage.
IMS (Industrial methylated Spirits) was found to soften the adhesive, but it seemed to activate the acids(?) in the fibres causing yellowing in the cotton blotting paper. Separation of the netting from the fibres was achieved using IMS, but if left on the fibres too long it solubilised the adhesive to form a thin clear film.
An approx. 60:40 combination of IMS:acetone in a sepiolite poultice was used. The IMS softened the adhesive sufficiently and the addition of acetone slowed down its effect, leaving us time to carefully remove the net before it solubilised the adhesive and drove it further into the fibres.
Because of the stickiness of the adhesive, only small areas, approx.5-10cm2, were treated at a time, although one conservator could have up to five small areas working at a time. A barrier of layer of cotton calico was laid on the cloak, a poutice put onto the cloth and covered with polythene. After approx. 5 minutes the adhesive was checked and if softened enough the poultice removed and the net carefully peeled back and cut away. Care was taken not to leave the poultice on too long to prevent the adhesive being pushed further into the fibres.
This was a successful method but considering the size of the cloak was very time consuming. Net removal took approx.100 hours.
Support of splits and tears in warps and wefts (structural support)
To support the numerous splits and tears, the common basketry technique of ‘Frankensteins’ – twists of coloured mulberry paper adhered in position to bridge across areas of damage - was used in two ways.
To support splits in the warps, lengths of the mulberry paper were twisted to approx. half to a third of the thickness of the warp and toned to match using Liquitex® acrylic paints. A line of starch paste (arrowroot starch + sodium alginate, 9:1, in water), was applied along the twist’s length, and the twist then nestled in the space between two warps, starting from a strong area, bridging across the split or weak area, and continuing on until reaching another strong area.
These twists can be found in between every other warp along the entire lower border of the tapestry woven section and the twined warps below.
To support splits in the wefts, the twists were made to imitate the spin and ply of the weft. Much thinner strips of mulberry paper were twisted in an Sdirection, and plied in a Zdirection, to make a ‘thread’ similar in thickness.
As per the warp supports, these were adhered to a strong area of the split, just above or below the split weft, carried across the damage area, and secured to a strong area on the other side, following the line of weft they were imitating. Where the damaged sections of the cloak were significantly misaligned (and due to stiffness unable to be re-aligned), the support twist remained horizontal and bridged wefts that wouldn’t have met originally, as this provided more even support and reduced the visual impact of the misalignment.
To ensure full contact, the twist was manipulated to ‘curve’ around each warp, but remain on the same side of the cloak, not move between each side as per real twining. Thus the twist takes the shape of a series of adjacent semi-circles, curving round one half of each warp.
Due to the stiffness of the fibres, the flat warps were not able to be reshaped or realigned during treatment, and so were supported in the current shape and position.
Most of the larger areas of damage were supported on the reverse of the cloak.
The smaller, more localised areas of damage were supported on the front of the cloak.
Choice of adhesive
Numerous starch pastes were tested and a literature search carried out to determine the most appropriate starch paste for use with the cedar bark.
10% wheat starch, 10% tapioca starch, and a 10% arrowroot starch + sodium alginate paste (9:1) were tested.
Based on working properties, the arrowroot/sod alginate paste was the most successful. The cedar bark to which the paper twists were being adhered to was still quite friable and not necessarily cohesive. The wheat starch was too slippery, and it was difficult to keep the twist in position as they dried. It did however seem to impart the most water to the twists, which could get a bit stiff from the acrylic paint, making them flexible enough to get good contact against the uneven surface of the cloak.
The arrowroot/sodium alginate was tackier and dried faster, allowing us to place our twist in the correct position and work faster across the cloak, but still transferred enough water to the twists to flex around each warp/weft. Literature and first-hand experience of senior conservators in the studio suggested it could still be removed easily with minimal water after ageing (e.g. a drop of water delivered on a small paint brush).
The tapioca was similar in working properties to the wheat starch, and although reported to have good flexibility over time, as we didn’t need this feature (the cloak was always to be displayed on a board), and as we weren’t familiar with its long term ageing properties, it didn’t seem to hold any advantage for us.
Support of heading cord
Mulberry twists were used to re-attach both the original and non-original heading cords that had split from the warps. Also, the very light coloured, non-original cord was toned with Liquitex acrylic paints to make it less noticeable. It was not removed or replaced as it was still supporting the original hide strip (which in most parts was still well adhered to it), and the handling involved would have caused significant damage of the brittle cedar warps.
Side braids
The tangled cords of the proper right side braid were encased in custom dyed nylon net to protect the cords (dyed with Lanaset® dyes). Reconstruction of the tangled cords was considered, but their fragility precluded this option. The net encasement was made wide enough to suggest the original width of the braid.
As so little of the proper left side braid remains, and the cords that do are prone to shedding and breaking with any handling, the remains were left to sit on the padded board with no further treatment. A large handling edge of the board near this braid will ensure it is not accidently touched during transit or study.
Padded support board
The cloak remains extremely fragile and not able to support its own weight. To provide full support for both display and storage, it was laid on a padded board constructed from ‘Timecare Board’ (also known as ‘Tycore’, an acid-free card with interior honeycomb structure). The corners and some edges of the board were strengthened with Bonda Wood Fill® super soft cream colour, and the board covered in thin cotton dommette and Baumann Ultra 123 cotton fabric, secured in place with Vinamul 3252 (pva adhesive) on the back. Baumann Ultra 123 was chosen as it is the colour for all large North American textile support boards.
This board is intended as both a display and storage board.
Infilling areas of loss
Discussions with the curator about how far to visually infill the many areas of loss concluded that we also needed guidance from the source community, the Nuu Chah Nuulth.
A document about the conservation and implications of various infill approaches was sent to the regional area museum that displays some Nuu Chah Nuulth cultural material, with a request to contact the Museum for discussion. Unfortunately we’ve had no response as yet.
With a lack of input from a significant stakeholder, the approach agreed with the curator was to treat the areas of loss as minimally as possible, and infill only those areas that were distracting and focused the viewer’s eye on the damage, rather than the cloak as a whole.
Thus smaller areas of loss were visually infilled by stitching brown coloured cotton fabric on the support board under the area of loss.
This approach for larger areas did not reduce the impact of damage as significantly, especially where the thickness of the highly textured object against the thin, untextured fabric infill was pronounced, such as near the heading cord.
Thus for two areas of loss along the heading cord a more textured, three dimensional infill patch was made. Lengths of coarse kozo fibres used in paper making were soaked and beaten flat into an expanded, flat piece. The nature of the fibres meant there were many holes and spaces between them. The flattened piece of kozo was then coloured with Liquitex® acrylic paints, and glued with PVA onto a toned piece of mulberry paper, cut slightly larger than the shape of the loss. Now quite a thick, stiff patch, the top edge was able to be rolled back under itself to mimic the shape of the heading cord. Further colour blending with acrylic paints was done, and bits of loose fibres stuck on with PVA adhesive gave more texture and thickness.
Because the cloak was to be displayed flat, when completely dry the patch was just placed under the area of loss, and not secured to the cloak in any way. If the cloak ever does need to be displayed at a (low) angle, a nap fabric such as Wynsiette or domette can be placed underneath the patch to ensure it doesn’t slip on the board.
These infills are completely removable without the need to intervene with the object. They reduce the impact of the losses, focusing the viewer’s eye on the parts of the cloak that still exist, rather than on the parts that don’t.
- Details
- Treatment