Conservation and Restoration

Paper Restoration

Paper Restoration

Materials for restoring paper and graphic documents. Tengujo Japanese paper from CTS in four weights, from 6 to 18 g, for reinforcements, mends, and linings; wheat starch for preparing paste, and Klucel G, an adhesive for paper and cardboard. For drying and humidification, Lascaux blotting paper, highly absorbent and with very good wet strength, and Sympatex membrane, waterproof to liquid water and breathable to vapor. And precision tweezers with LED light, in straight and curved versions, for placing small mends and reinforcement strips.

Frequently asked questions about paper restoration

Which adhesive to use for paper restoration: wheat starch paste, methylcellulose, Tylose, or Klucel G?
The choice depends on the task and the amount of water to be applied. Wheat starch paste is prepared by cooking (it gelatinizes between 58 and 64 °C) and is the main adhesive in Western paper conservation: for hinges, mends, linings, tissue repairs, and media consolidation. Methylcellulose (Methocel A4M) creates a clear, tenacious, and flexible film, and in linings, it is mixed with paste. Tylose MH 300 P2, a cold-water soluble cellulose ether, is used as an adhesive in aqueous solution. Klucel G is used as an adhesive for paper and cardboard and also dissolves in ethanol: it is useful when it is important to introduce little water.
Hollytex or Reemay: which non-woven polyester to use for paper?
It depends on the task. Both are non-woven polyesters used as intermediate supports in paper washing; while the work is wet, it is best kept between permeable non-woven polyester supports. Reemay has more surface texture and grips wet paper well during washing; it comes in 17, 34, and 71 g/m² (grades 2250, 2014, and 2024). Hollytex, being calendered, is smoother: it is indicated when there is concern that the texture may transfer to soft media or the paper itself. It also serves as a separation layer between sheets of blotting paper and as an interleaving material; it comes in 34 g/m².
What are blotting paper and Sympatex used for in paper restoration?
They are complementary: the blotting paper absorbs and the membrane allows vapor to pass through, but not liquid water. Lascaux blotting paper, with long, strong fibers, very absorbent and with very good wet strength, is used for drying and flattening after aqueous treatment, for capillary washing, and as a water reservoir in humidification. Sympatex is a compact, hydrophilic, pore-free membrane made of polyether-ester. In the humidification package, the wet blotting paper provides water, and the membrane acts as a barrier: the work receives vapor, not liquid water. During drying, the smooth membrane against the paper helps preserve the satin surface.
What tools are used to handle fragile paper and small pieces during restoration?
The first thing is the support: work on a flat table, with the paper inside its folder or on a rigid support, touching it only in areas without images or text and with clean, dry hands. To separate fragile sheets, a paper lifter is used: a microspatula, thin bone folder, or rigid cardboard. Wet and damaged paper is lifted by sliding a polyester sheet underneath. The bone folder, made of bone or plastic, also serves for folding and burnishing. To place small mends and reinforcement strips, tweezers are used, such as the straight tweezers and the curved precision tweezers with LED light.
Does Klucel G dissolve in water or in alcohol?

In both, with one caveat worth knowing: above 45 °C it stops being soluble in water. It also dissolves in many polar solvents, and does not in most non-polar ones. In a 2 % solution its pH is between 5.0 and 8.5.

Cold water, ethyl alcohol, methanol, 95 % isopropanol and propylene glycol give a clear solution; with acetone or pure isopropanol it comes out hazy, and it does not dissolve in white spirit, toluene or xylene. And if a water-based solution has warmed up and turned cloudy, it is not lost: cooled below 40 °C with stirring, it redissolves and recovers its viscosity.

How do you prepare Klucel G so it doesn't form lumps?

By first wetting the powder in about six times its weight of water at 50-60 °C, no hotter than 60: at that temperature it gets wet but does not dissolve. Then top up with cold water and stir, without vigorous beating, until no gels remain.

What kind of film does Klucel G leave when it dries?

A flexible film with no plasticiser, which does not turn tacky even at high humidity. And it remains soluble in cold water and polar solvents; it only stops being so if it is crosslinked with another resin.

Is Klucel G hazardous?

Its safety data sheet does not classify it as hazardous under Regulation (EC) 1272/2008, and it carries no hazard label. It is worth knowing that it is a combustible dust: its lower explosive limit is 30 g/m³ and it self-ignites at 420 °C. And that it should not be mixed with oxidisers or with strongly alkaline or acidic materials.

Which weight of Tengujo Japanese paper to choose: 6, 9, 12, or 18 g?
It is decided according to the work. For reinforcement, tissue is generally chosen to be lighter than the original paper, and linings, somewhat lighter than the original. For gap fills, thicknesses are matched, overlapping several sheets if necessary, and for text on the reverse side, a thin, light tissue is sought. Tengujo 6 g, Tengujo Kashmir 9 g, and Bib Tengujo 12 g are made from abaca fiber (Manila hemp). The range is completed by Tengujo 18 g.
ItemWeightpHCompositionSize
561 Tengujo6 g/m²6,7100 % manila480 × 940 mm
502 Tengujo Kashmir9 g/m²6,7100 % manila480 × 940 mm
240 BIB Tengujo12 g/m²7,1100 % manila480 × 750 mm
508 Tengujo18 g/m²6,7100 % manila460 × 690 mm

Which weight suits a given treatment is the conservator’s call.