Visit the Conservator

Flattening distorted paper – a restoration project in pictures

Follow our paper conservators as they flatten a number of 200-year-old Goya prints that had become undulated with age.

Otro modo de cazarlos a pie. KKS1975-876

How conservators prepare art for display

Whenever a work of art is due to be put on display it will first be checked by a conservator. The conservator will assess its condition, any damage, and decide on whether any treatment is required before the work is presented – and exposed – to the public. Fortunately, great damage is rare, but even small-scale damage requires tender love and care.

As far as works on paper are concerned, the conservator’s work will usually involve remounting the work in a new passepartout made from acid-free materials, stabilizing any tears along the edges, performing a dry clean to remove surface dirt, filling in any missing areas, wet cleaning to remove blemishes, and/or mending and flattening bends and deformations by immersing the artwork in a water bath.

Paper and water

Most people would think that paper cannot withstand water without losing its strength, shape, and in some cases colour. In the vast majority of cases, however, this is not true. Even so, wet-cleaning a work of art on paper does, of course, require that the media used (ink, etc.) – as well as any pigments used to dye the paper – are stable in water. The overall condition and strength of the paper is also an important factor influencing the choice of cleaning method. Wet-cleaning old, crisp, and deteriorated paper may be very difficult. The vast majority of graphic techniques are waterproof, so printed art in its pure form, without any painting involved, will usually be able to withstand a bath.

A destorted 200-year-old print

In preparation for the museum’s autumn exhibition in the Royal Collection of Graphic Art, Manet’s Goya, a number of Francisco de Goya prints were wet-cleaned in order to flatten bumps and severe deformations in the paper.  The works, 13 in total, are part of a series of dark images executed as line etchings; they are aquatints executed with the use of scraper, drypoint needle, and burin. All prints date from the period 1815-1816 and are in excellent condition; however, they all had similar deformations across the printed area. These lumps were very noticeable and detracted from the subject matter, and they also constituted a conservation risk for the artworks: the bumps made them far more prone to wear and made the print media more liable to be scraped off. This in spite of the works being well mounted in a passepartout; the bumps meant that that the mounting completely lost its intended protective effect.

Bathing, drying, mounting

All 13 prints underwent the same wet cleaning and drying process before being mounted in a new passepartout. These are all quite typical conservation measures and are commonly seen in any paper conservation workshop. The pictures below allow you to follow the process step by step and to gain insight in how paper conservators work with art in their day-to-day tasks:

The work in its passepartout prior to treatment.

The work lit from the side; the light accentuates the deformations in the paper.

The verso/back of the work, showing prominent bumps.

A vat of water, a spray flask of demineralised water, and pieces of synthetic fleece are prepared for use.

The work is dipped into the vat, which has been filled with lukewarm water.  This is done in incremental stages; the work is first placed floating face up on the surface of the water while being immediately and gently sprayed with demineralised water. The approach ensures that moisture is introduced from both sides, preventing the paper from curling up. Once the entire sheet is moistened through it can be submerged entirely in water – still resting on the fleece, which must be cut to a larger size than the artwork itself.

After approximately 10 minutes – depending on the condition of the work, its quality, and the degree of dirt found on it – the print is gently pulled out. This is done by grabbing the corners of the fleece and slowly pulling it up across the edge of the vat. The method causes the wet paper to stick and the water to run off.

Holding the work at a slight angle allows even more water to drain off.



The work is immediately sandwiched between thick filter paper and plates of smooth polyester. In this case, where the deformations were mainly found in the printed areas of the paper, emphasis was placed on flattening that particular part. Filter paper adjusted to fit the area in question was placed at the top of the sandwich, at which point sand bags were added to create extra pressure. This means that the central part of the paper will dry out first, pressing the deformations out to the edges, which were not covered by filter paper.

The drying process must be carefully monitored and controlled, and the filter paper used to draw the moisture out of the work must regularly be replaced by clean, dry pieces. Once the deformations appeared to have been removed from the middle of the work, the entire work was placed in a drying sandwich featuring several layers of filter paper and subjected to diminishing pressure.



Once the work has dried out completely it has become flattened, the former deformations vastly reduced.

The next stage consists in hinging the work into a new passepartout made from acid-free cardboard. The work is hinged in place by means of so-called V-hinges along the upper edge. This makes the hinging invisible while still allowing scholars to inspect the back of the work, for it is only fastened at the top.


Glue (a dense, low-moisture, short-chain adhesive) is applied to the hinge, which is made out of Japanese paper that contains long fibres. The hinge is then carefully placed behind the print, which is being kept in the exact end position desired in relation to the passepartout.

Light pressure is applied from the front above the hinges in order to prompt the adhesive to dry more quickly, thereby preventing the glue from causing any new deformations and/or discolouring.

Lifting the work reveals the V-shaped hinge at work.

The work is now clean, flat, and mounted in a new passepartout, ready to be framed and put on display.

Updated: 26.apr.2018
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