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Restoration of tears and
gaps

Japanese paper repairs:

 

Japanese paper, or washi, is one of the main materials used in the conservation and restoration of old documents and books. Among its varieties, kozo stands out particularly for its exceptional strength and flexibility, making it ideal for restoration work.

 

Origins of washi

Japanese paper arrived in Japan in the 7th century via Korea and China, favored by Buddhism, which required large supports for sacred texts. The imperial courts then developed mass production, with dedicated plantations of fibrous plants such as kozo and hemp.

 

The three main fibers

Washi is made from the bark of three traditional shrubs:

  1. Kozo: Very long fibers (up to 3-4 mm), flexible and tension-resistant; thin but strong paper, slightly textured. For document restoration, binding, and tear repair (long fibers interlock perfectly).

  2. Gampi : Fine, tightly packed fibers , glossy and translucent surface. For fine printing and calligraphy.

  3. Mitsumata : Short fibers, satin and smooth paper. For writing and ritual wrapping.

 

 

 

Why kozo in restaurants?

Kozo is preferred for the preservation of papers and books due to its unique advantages:

  • Mechanical resistance: Even when thin, it withstands tension and bending without tearing, perfect for reinforcing fragile documents.

  • Flexibility and elasticity: It adapts to the movements of old books without cracking, unlike rigid Western papers.

  • Longevity: Pure natural fibers, without added acids, guarantee stability for centuries; ideal for durable and reversible interventions.

  • Controlled transparency: Slightly translucent, it blends discreetly during rework (re-gluing, dubbing).

In practice, its long fibers allow for perfect integration during repair, such as in the restoration of parchments or damaged pages.

Kozo making

  • Harvest: Branches cut in winter in humid regions of Japan; inner bark boiled and beaten to release the long fibers.

  • Paste: Mixed with water and vegetable mucilage for a homogeneous suspension.

  • Leaf: Formed on a bamboo frame by cross-shaping, pressed and air-dried for a natural texture.

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Illustration of the steps in the making of Japanese paper
Royalty-free image, internet source

Restoration of tears and gaps

Once the document to be restored has been cleaned—that is, dusted and erased—external elements can be applied to the artwork if necessary. Indeed, since the surface of the support is clean, the introduction of moisture via glue will not risk staining or damaging the document.

The reinforcements are made with Japanese paper because this paper is neutral and has long fibers; these long fibers allow for a resistant restoration over tears.

Weight depending on use:

 

3 g/m² : Lightweight linings on heavily damaged pictorial/written surfaces (minimal reinforcement)

 

6 g/m² : Full linings, pleat reinforcements

 

9 g/m² : Repairs of tears, very weak creases, linings

 

17 g/m² : Tabs, gap filling (thin documents), linings

 

23 g/m² : Tabs, fillers, reinforcements

 

30-40 g/m² : Filling of gaps (chosen according to color, thickness and texture close to the original document)

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Paper choice : It depends on the state of deterioration, the weight, the color and the information contained in the original document.

The restoration paper used will therefore depend on the state of degradation of the document, the thickness (density, grammage) of the paper of the document, its colour and the information it contains.

Gap filling

It is necessary when:

  • A lack of material damages the integrity of the document or its visual identity.

  • A lack of material may lead to physical or mechanical degradation: for example, an unfilled deficiency may cause certain tears to widen or create tension in the paper.

  • The client wants it: their requirements guide the restorer, especially for the color of the filling (gap left pure or retouched to blend the restoration paper into the whole).

Restoration of tears on the pages of an old herbarium
© Carole Jeanneret (Work completed in 2025)

How is the reinforcement of tears and gaps carried out?

 

To repair a tear, it is essential to ensure the artwork is perfectly clean before placing a piece of blotting paper and a non-woven fabric under the area to be reinforced. Next, a Japanese paper is selected based on its weight, strength, and the purpose of the restoration. This paper is never cut, but always torn to preserve the fibers, ensuring effective and virtually invisible reinforcement.

 

A piece of Japanese paper is torn to a length equivalent to the tear, with an overlap of approximately 5 mm, and to a width of approximately 1 cm. Zin Shofu glue or Tylose is then applied to the reinforcing paper, which is then placed over the tear.

 

Finally, to prevent tension and halos during drying, a new non-woven fabric and a new piece of blotting paper are placed over the reinforcement. Pressure is then applied using a weight.

 

 

Restoring tears on an artist's drawing
© Carole Jeanneret (Work completed in 2026)
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Wheat starch glue

 

It is the most widely used vegetable-based adhesive in conservation/restoration because it is the most reversible (water-soluble) and the least aggressive to paper; combined with fungicides, it does not attract microorganisms and thus possesses excellent conservation properties. It is primarily used for paper repairs, filling gaps, repairing tears, and lining. It does not color the artwork and therefore allows for a neutral restoration—chemically, mechanically, and physically.

 

Wheat starch glue is sold in powder form and is prepared in a saucepan, saucepan or microwave mixed with demineralized water.

 

 

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Tylose MH 300 P glue: Methylcellulose glue

 

This cellulose glue is neutral and reversible and has interesting mechanical qualities; indeed, it is particularly "elastic" and therefore resists better mechanically than starch glue.

It is used for multiple tasks: peeling (as a poultice, it allows the original adhesives to be reactivated and thus the paper elements to be peeled off), cleaning (also as a poultice, it allows the impurities embedded in the paper to be lifted), gluing (especially for linings, it is used for its elasticity; it dries less quickly than starch glue, which is sometimes a factor of choice for the restorer, but its adhesive power is weaker than starch glue).

It is sold in powder form and is prepared by dissolving it in water until it forms a more or less viscous gel.

The glues used

Zin Shofu Glue
Image © Promuseum
Tylose MH 300 Glue
Image © GMW Shop

Materials and tools:

 

  • Non-woven fabrics

  • Blotters

  • Mylar

  • Layers

  • Teflon folder

  • Pliers

  • Water brush

Suppliers:

 

 

© 2026 by Conservation des documents et des livres. Powered and secured by Wix 

 

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