Repairing Paper

One of the questions I hear most as a book and paper conservator is ‘So… How do you actually repair a piece of paper?’ I thought that with this blog post I would shed some light on this frequently asked question.

Tears in paper are one of the most common types of damage we see as conservators. As books and documents are used and handled over decades, tears often develop in the pages. The ease and rate at which this happens depends on a number of factors, including the quality of the paper, the environmental conditions in which it is stored, and of course the way in which it is handled.

So what is the process of repairing a tear in paper? The most simple and frequently used method employed by conservators requires only two materials: thin Japanese paper (or an equivalent) and wheat starch paste.

Wheat starch paste is purified wheat starch. It usually comes in powder form, and to make it usable we mix it with water and then heat it up so that the granules swell and absorb the water, forming a sticky, gel-like adhesive.

There are a number of reasons that conservators usually use wheat starch paste for paper repairs. Firstly, it is easily reversible: if you re-introduce water to a repair, the adhesive will become sticky again and allow you to take the repair off. This means that the repairs we add to objects could be removed at a later date if desired. Secondly, wheat starch paste has good ageing properties, meaning that it will not cause problems by going yellow with age.

Japanese paper is generally made from the fibres of one of three different plants—kozo, gampi, or mitsumata—though combinations are also found. The papers made with each fibre have slightly different properties to one another. The favoured type for paper repairs is kozo paper, which is made from the fibres of the paper mulberry tree. Due to its long, strong fibres, kozo paper can be made very thin (down to about 3.5 grams per square meter!) while still remaining very strong relative to its weight. Handmade papers, made in the traditional manner in Japan, are the best to use. However, sometimes these are very difficult to get hold of, so conservators also use machine-made alternatives, which also have very good properties.

The following photographs show the method of doing a simple ‘patch’ paper repair. The first step is to check that the tear is aligned and the paper sitting in the right place, as it is here.

The Japanese paper is then cut to the right shape, forming a ‘patch’ that will be applied over the tear. Sometimes, a light box or light sheet is used to help the conservator to trace the correct shape. We try to keep the repair as small as possible while still making it effective, so that we are adding the least amount of new material to the object.

Before using the Japanese paper, we check to see if there is an area of torn overlap. If there is, wheat starch paste is carefully brushed along this ‘scarfed’ area to hold the tear in place and begin the repair.

Next, the Japanese paper is coated with a thin layer of wheat starch paste. As you can see in the photo, for paper repairs we make the paste quite dilute—about the consistency of skimmed milk—which means we can achieve a very thin, even coating of adhesive that will not stiffen the paper too much in the repaired area.

The Japanese paper is then placed over the tear and rubbed down with a tool called a ‘folder’, often through silicon paper to prevent the tool from unintentionally burnishing the paper. Folders can be made of bone or, as here, of Teflon. When rubbing down the repair, we are making sure that it adheres really well to the surface of the original paper, and that all the tiny fibres are stuck down.

The repair is then left to dry between blotters and silicon paper, and under weight. The silicon paper stops the repair sticking to the blotters as it dries, and the weight ensures it dries with good adhesion. If the original paper is more fragile, felts can also be added to help cushion the surface from damage.

Finally, the repair is trimmed along the edge of the paper.

As you can see, the Japanese paper is so thin that the repair ends up being almost invisible. Nevertheless, it is strong enough to hold the tear together, and thin enough to flex with the paper as needed.

This is not the only way to carry out paper repair. Sometimes, the media on the paper is water-soluble and so excludes the use of a water-based adhesive like wheat starch paste; in these cases, a different adhesive and/or method is required to apply the repair safely. More minimal repairs are also possible, for example using tiny ‘sutures’ to bridge the tears instead of patches that cover the tear entirely. However, the above method is frequently employed for its simplicity, speed, and effectiveness.

We definitely never use Sellotape!


The treatments described in this blog post and others in the Conservation series are carried out by a qualified conservator. If you have an item in need of conservation, it is always best to ask a conservator for advice. In the UK and Ireland, you can find a conservator through the Institute of Conservation’s Conservation Register.

The Minton Archive one-year conservation project is funded by:
Logos of the Art Fund, The Pilgrim Trust, The Wolfson Foundation, and the National Manuscripts Conservation Trust