- Laponite S and JS are identified as hydrous sodium lithium magnesium fluorosilicate. Laponite is a totally synthetic product. Salts of sodium, magnesium and lithium are combined to produce a powder that is then filtered, washed, dried and milled. The process is described on the Laponite website: <www.scproc.com/laponite/prod/rz.html>. Most conservators contacted used Laponite RD
- This article is the result of research carried out at Queen's University, Canada, in partial fulfillment of the Master of Art Conservation degree and was presented at the annual meeting of the Western Association for Art Conservation, 6–9 Oct 2002 Portland, USA. There has been some study of the difficulty in removing gel poultices, in which residues were detected and substances were observed to migrate into the paper substrate, see: Aviva Burnstock and Tanya Kieslich, ‘A study of the clearance of solvent gels used for varnish removal from paintings‘, ICOM: Pre-prints of Eleventh Triennial Meeting, Edinburgh, 1996, 253–262; and Agnes Blüher, Gerhard Banik and Elisabeth Thobois,’.he application of Carbopol gels and enzyme containing methyl cellulose gels for removal of starch based adhesives in albums’, International Conference on Conservation and Restoration of Archive and Library Materials, Erice, 1996, 791–809. There are no other studies known to the author which examine discolouration on paper or parchment after the use of Laponite poultice, although Blüher et al mention discolouration of Carhpol poultice on paper
- A gel is a high viscosity, pseudo-solid colloidal dispersion of a solid in a liquid, and a sol is a low viscosity colloidal dispersion of a solid in a liquid
- Laponite website: <www.laponite.corn/pdf/broch/formulation.pdf>
- 1986 . The Conservator , 10 : 5 – 9 . Laponite website: <www.laponite.com/pdf/safety/Laponite%20D-RD-ED%20SDS.pdf>. The high pH of Laponite (from 8.8 according to the following sources) has been a cause for concern when enzymes were incorporated into the gel (see V. Chapman, ‘Amylase in a viscous medium—textile applications’,7–11);or when acidic materials such as proteins were being treated (see L. da Silveira, ‘A note on the poultice cleaning of feathers using Laponite RD gel’, Studies in Conservation 42.1 (1997): 11–16). Recommendations for adjusting the pH may be found at: <www.laponite.com/pdf/broch/formulation.pdf>
- Laponite website: <www.laponite.com>
- This behaviour is known as thixotropy and when agitation ceases, the gel reforms
- Laponite website
- Lee , L.-M. 1997 . ‘Investigations into the use of Laponite as a poulticing material in ceramics conservation’ . V&A Conservation Journal , 22 : 9 – 11 . Chapman 7–11. See also: D. Ling, ‘Laponite poulticing’, Conservation News 46 (1991): 1–11; G. Spicer, ‘A sticky business: The removal of hide glue from silk’, Harper's Ferry Regional Textile Group, 11th Symposium, 12–13 Nov 1992 (Harper's Ferry, WV: Department of the Interior, Harper’. Ferry Center, 1992) 67–72
- da Silveira 11–16
- Lavédrine , B. ‘Effet de la Laponite sur les papiers albuminés’, unpublished typescript, Centre de Recherches sur la Conservation des Documents Graphiques (rggi) 1 – 3 .
- Webber , P. 1984 . ‘The conservation of fans’ . The Paper Conservator , 8 : 4 – 58 .
- Yates , S. A. 1984 . ‘The conservation of nineteenth-century tracing papers’ . The Paper Conservator , 8 : 2 – 39 .
- 2001 . 21 ‘Canadian War Museum Project’. Canadian Association for Conservation Bulletin 26.4
- This practice is employed at the National Archives of Canada and was explained to the author as fulfilling this purpose, however, Laponite is not soluble in ethanol and therefore ethanol cannot remove it by chemical dissolution. While interning at the National Archives of Canada, the author unsuccessfully attempted to dissolve a sample of dried Laponite gel in ethanol. In addition, Rockwood Additives Ltd indicates that one of the desirable properties of Laponite when used as a coating is its resistance to dissolution by common solvents. Ethanol may assist in the mechanical removal of Laponite residues by penetrating the substrate to aid in the lifting of residues that are then removed by a cotton swab. For further information, see the Laponite website: <www.scprod.com/laponite/prod/14.html>
- Lee et al 10
- da Silveira 14
- Evans , C. 2002 . personal communication, 17 Jan
- Evans . See also: <www.scprod.com/laponite/prod/14.html>
- Most Arches papers are sized with gelatine, however, information on any additives or surface sizing of the papers used in this study was not available at the time of purchase. It has been pointed out to the author that sizing materials and other additives, or water-soluble impurities in paper, may be extracted by an aqueous poultice such also Laponite and may affect the ageing properties of residues. Sizing materials may also influence the ability of a poultice to penetrate a paper's fibre network, potentially affecting the retention of poultice films by the substrate. While these considerations were not a part of the present study, future work should incorporate them
- This concentration was chosen based on practice employed at the National Archives of Canada
- Directions for dispersion are given on the Laponite website: <www.laponite.com/pdf/broch/formulation.pdf>
- MacLean , B. 2000 . ‘Resin-coated photographs: Searching for an appropriate labelling device’, diss., Queen's University, Canada 23
- A series of Cargille liquids of known RI were used for this. Using the Becke line phenomenon, it was determined whether the RI of Laponite was greater or less than a particular Cargille liquid and a different liquid was then tried. By process of elimination, the Laponite sample was determined to have an RI between two Cargille liquids in the series
- SEM work was carried out by John Stewart of Parks Canada in Ottawa, with the assistance of the author
- The attenuated total reflectance attachment for the FTIR allows analysis without sampling from the surface of the paper or parchment. The entire paper or parchment sample was placed on a stage and secured with a clamp. The infra-red beam was directed onto the sample through the diamond tip of the clamp, penetrating the sample to just a fraction of a wavelength beyond the surface. The beam was then reflected and travelled back through the diamond tip
- ASTM Standard D 2244–89 . 1991 . ASTM Standards on Color and Appearance Measurement, , 3rd ed. 81 Philadelphia : American Society for Testing and Materials .
- 2002 . These conditions for artificial ageing of paper were suggested by Paul Begin, Conservation Scientist at the Canadian Conservation Institute, personal communication, 13 Feb
- Three test samples of parchment measuring 25 × 60mm (H × w) were placed in the environmental chamber under these conditions for two weeks to determine if shrinkage would occur. After 14 days, the samples had shrunk 2–3mm in width and 0–1mm in height. This was deemed to be within acceptable limits. There was no dimensional change observed in the paper samples
- Abdel-Maksoud , G. and Marcinkowska , E. 2000 . ‘Changes in some properties of aged and historical parchment’ . Restaurator , 21 : 139
- The presence of silicon in the paper and parchment samples may be a by-product of the manufacturing process, such as the addition of silica filler to paper, or rubbing skins with pumice
- Cold pressed paper spectra are shown here as representative of all paper spectra. Please note that the EDX spectra are not all on the same scale. While attempts were made to record the spectra on the same scale, it was difficult to obtain peaks that were equally visible for all samples. The scales were adjusted to make the spectra easier to read, however, the spectra cannot be directly compared for semi-quantitative purposes
- Cold pressed paper spectra are shown here as representative of all paper spectra
- Flesh side parchment spectra are shown here as representative of all parchment spectra
- 1997 . 109 – 126 . Guidelines for perceptible colour change were those used by Stefan Michalski and Carole Dignard in their article, ‘Ultrasonic misting, Part 1. Experiments on appearance change and improvement in bonding’ Journal of the American Institute for Conservation 36.2. On p. 113 they explain that this value is based on a colour change scale used by the International Organization for Standardization (ISO) for testing lightfastness
- It should be noted that one extreme outlier, PF07 un, was not included in the analysis
The Paper Conservator
Volume 27, 2003 - Issue 1