This allows a great number of adhesive strengths from one material. This is the primary adhesive for Japanese conservators. In addition to the functions which parallel those in which Western conservators use wheat starch paste, this adhesive is used for wood to wood bonds in scroll mounting. This paste is felt by its advocates to have a degree of viscosity not matched by paste made from dried starch.
See Wills Compared to freshly-made paste, this adhesive is reputed to be weaker and more flexible. It is less prone to cause planar distortions in paper supports.
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Typically used at least eight years after its preparation, it imparts flexibility in multiple lining layers where it is used for secondary and tertiary backings, as well as in scroll linings. This paste is not generally used in the U. This is generally considered to be a weaker adhesive than wheat starch paste. However, it is uncertain what the amylose content is for American and European rice starches.
Differing amylose percentages and individual working habits of conservators may contribute to contradictory statements regarding properties of rice versus wheat starches. Possible uses are in situations where wheat starch paste would be too strong.
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Some conservators believe that rice starch paste is not as likely to cause a grayish haze or stain when it dries. The following is from Kirby Dextrins are modified starches whose molecular structure has been changed through the use of heat, acid, alkali, or other catalytic conversions. Dextrins have been widely used for stamps, labels, and paper tapes, where the adhesive is moistened for application.
These are encountered in former linings as historical adhesives. Contain brown chaff and particles. Not currently recommended for use. Gums are relatively weak adhesives; however, they function well as protective colloids, preventing agglomeration and settling of finely-divided particles. Because of this property, they have been used, probably since ancient times, as binders in painting media. Gums have been used by watercolorists and miniaturists to saturate and intensify colors, especially to create modelling. Gums were also used to saturate dark areas in prints, particularly lithographs.
Gums have a wide variety of commercial uses, particularly in the food and drug industries. Some gums e. Gums from fruit trees e. Mucilages, related to gums, are plant materials extracted from seeds, roots, and other parts of plants. The term "mucilage" is broadly used, however, to describe general-purpose paper adhesives prepared by cooking gums in water with odorants and preservatives Davidson , Gums have not been widely used in conservation treatments.
Agar or agar-bearing algae can be purified to isolate the hydrocolloid agarose, which has been popularized by Richard Wolbers as a gel medium in which enzymes can be suspended for poulticing procedures.
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Agar is widely used as a microbiological medium and commercially in the food and pharmaceutical industries. Funori has been used in Japan since as an adhesive and sizing material Chapman , Japanese scroll mounters use funori to attach facing papers to paintings and to consolidate flaking paints. In , a process was patented in Germany for reacting cellulose with dimethyl-sulfate in the presence of bases to produce a water soluble cellulose. In , the first industrial production of methyl cellulose began in Germany using gaseous methyl chloride to etherify cellulose.
Several years later, commercial production of sodium carboxymethyl cellulose began world-wide Kennedy et al. Since then, the processes have been modified and production of a variety of cellulose ethers has expanded to millions of pounds yearly. Commercially, cellulose ethers are used as thickeners, anti-redeposition agents, and protective colloids for liquids in the food, paint, adhesive, and oil-well drilling industries.
In paper conservation, cellulose ethers have been used alone or with starch pastes for lining, hinging, and mending. Their moisture holding, surfactant, and anti-redeposition properties may be used to advantage as poultices for removing stains, old adhesives, and other accretions.
https://belgacar.com/components/espionner/localiser-adresse-ip-php.php Dilute solutions have been used for sizing or resizing paper. Cellulose ethers have also been used for consolidating flaking or friable media and as a binder for cellulose powder fills. Because some cellulose ethers become less soluble as water temperature increases, they have been used as facing materials during warm aqueous treatments. Cellulose acetate was first developed in France in by the acetylation of cellulose.
Industrial production of cellulose acetate began to replace the highly flammable cellulose nitrate as a coating for airplane wings and fuselage fabrics during World War I. It was not manufactured as a film on a large scale until The properties of cellulose acetate are varied by the degree of acetylation. In the plastics industry it is suitable for both injection molding and continuous extrusion. In paper conservation cellulose acetate has been used in sheet form for the lamination of documents, or in dilute solution as a consolidant for flaking or friable media.
However, this film formerly qualified as appropriate archival laminating film.
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Adhesives such as gelatin, parchment size, hide glue, bone glue, and fish glue are collagen-based. Adhesives of animal origin have been used since ancient times. Fish glues have been in use since the eighteenth century.
North American paper conservators generally use the purest forms, gelatin and parchment size, as consolidants, fixatives, and sizes and in the treatment of parchment. Other bone or hide glues are used by Japanese conservators. Russian isinglass, a pure fish collagen, is used extensively in Eastern Europe. Casein is a traditional adhesive which has been used since ancient times. It varies from the collagen adhesives in source, solubility, permanence, and strength.
Casein has been used as a binder for pigments and painting grounds, as well as for paper coatings. It has been recommended in contemporary artist handbooks as a matte fixative for pastel Wehlte , PVA resins have been commercially available since the s with dispersions available since the s. They are used in conservation primarily as varnishes for paintings, media for inpainting, consolidants for insecure media, adhesives for facings, and as heat or solvent-activated adhesive films. PVA is a thermoplastic, odorless, non-toxic, essentially clear and colorless resin.
It has a noncrystalline structure which is relatively branched rather than linear Skeist , , PVA polymers are "among the limited number of polymers adapted by conservators since which have a common characteristic, they possess 'reasonable' flexibility without the need of added plasticizers" Stolow, Feller, and Jones , Viscosity grade, solubility, and hardness vary with the MW of the polymer.
Methods of adhesion include solvent evaporation, pressure activation, and heat sealing. PVA dispersions were developed in the s, although major technical developments did not occur until the s and s Skeist , Dispersions consist of minute particles of PVA polymer suspended in water. Polymer dispersions are frequently referred to as emulsions, which is a misnomer. Unlike PVA solutions, PVA dispersions have low viscosities even at high concentration of solids and at high molecular weights.
PVA dispersions form strong, flexible bonds to many materials, although complete film formation may take several months at the proper temperature Feller, Stolow, and Jones , Homopolymers of PVA e. PVA dispersion polymers can be either homopolymers or copolymers. Homopolymers require the addition of an external plasticizer, which make them susceptible to those usual aging problems typically associated with externally plasticized materials: embrittlement, discoloration, insolubility, staining. Copolymers were developed to overcome these problems with the comonomer acting as an internal, and therefore, stable plasticizer.
In conservation, PVA dispersions have been used as adhesives in book binding and box making; a lining adhesive for paintings; an additive to paste for mending, mounting, hinging; a heat-activated adhesive; and a consolidant. Poly vinyl alcohol thermoplastic resin solutions have been commercially available since the s, but were not used in conservation until the s. They have been used by conservators as adhesives, consolidants, coatings, sizes, and filling materials.
In industry they have been used for these purposes and as emulsifiers, binders, barriers, and stabilizers. In adhesive formulations, they are often found in combination with poly vinyl acetate emulsions. The various grades of PVOH resins provide films that differ in water and solvent resistance, adhesion, flexibility, and elongation Skeist , Acrylic polymers were developed for industrial use in The Fogg Art Museum began experimental use of the methacrylate polymers Lucite 44 and 45 now Elvacite and in the early s.
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