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Certification

Restoration

Restoration recommendations, levels of intervention, choice of restorer and monitoring of works.

Updated : October 28, 2026· 3 min read

Intervene as little as possible, as well as possible

Taj Mahal, Back View of the Rest-House, with Figure, Dr. John Murray (c. 1858–1862)
Taj Mahal, Back View of the Rest-House, with Figure, Dr. John Murray (c. 1858–1862)

The conservation report recommends; it does not restore. Works are entrusted to a restorer of your choice, according to shared ethical principles: reversibility, minimal intervention, full documentation.

This page explains how recommendations are prioritised, what the levels of intervention cover and how works are monitored and recorded in the Registry.

An undocumented restoration may affect the value of the work: it must be declared and entered in the work passport.

  • Reversibility
  • Minimal intervention
  • Documentation

Restoration in figures

4levels of intervention
3ethical principles
100%of works entered in the passport
12 monthsfor a follow-up report after works

The levels of intervention

From least invasive to most invasive
LevelNatureExamples
1. Preventive conservationImprove the environmentLight, humidity, framing
2. Conservation treatmentStabiliseRefixing flakes, dusting
3. RestorationRestore legibilityCleaning, filling losses
4. Major interventionWork on the structureRelining, consolidating the support

From recommendation to monitoring

  1. Recommendations

    The report prioritises interventions: urgent, useful, optional.

  2. Choice of restorer

    You choose a professional, preferably from the directory of conservator-restorers.

  3. Quote and agreement

    A written quote describes the treatment, the products and the risks.

  4. Works

    The restorer documents each step with photographs before, during and after.

  5. Declaration

    The restoration file is filed with the Registry and added to the work passport.

Altarpiece with Relics - God the Father, Joseph Matthias Götz (1735–40)
Altarpiece with Relics - God the Father, Joseph Matthias Götz (1735–40)
Seascape with Open Sky, Eugène Boudin (1860)
Seascape with Open Sky, Eugène Boudin (1860)
Study for "Bathers at Asnières", Georges Seurat (c. 1883–84)
Study for "Bathers at Asnières", Georges Seurat (c. 1883–84)

Three ethical principles

Choosing your restorer

Use a qualified, insured professional able to present references on works of the same kind. OIMAP publishes a directory of accredited conservator-restorers.

Avoid any “commercial” intervention (excessive cleaning, overpainting): it may reduce the value of the work and make any later expert examination difficult.

Conservation or beautification restoration

The Judgment of Midas, Nicolaes Clock (1589)

Conservation

Stabilise and preserve
  • Treats the causes of deterioration
  • Respects the original
  • Documented and reversible

Recommended by the report.

The Shepherd, Paulus Potter (1644)

Beautification

Improve the appearance
  • Extensive retouching
  • Products sometimes irreversible
  • Risk of loss of value

To be avoided unless necessary.

A documented restoration

  1. Before works

    Complete photographs and survey.

  2. Cleaning

    Solvent tests and trials on discreet areas.

  3. Consolidation

    Refixing or filling of losses.

  4. Retouching

    Reversible integration of losses.

  5. After works

    Photographs, report and entry in the Registry.

Case study: flaking paint

An urgent painting

Situation

A report notes lifting on a 19th-century painting displayed in a sunny drawing room.

Actions
  1. Urgent recommendation: refixing of the flakes.
  2. The owner chooses a restorer from the directory.
  3. The works file is filed with the Registry.
Outcome

The painting is stabilised, moved out of the sun and the passport is updated.

Study for "A Sunday on La Grande Jatte", Georges Seurat (1884)
Study for "A Sunday on La Grande Jatte", Georges Seurat (1884)
Fragment of a belt (hizam) (1800s)
Fragment of a belt (hizam) (1800s)
An Indigo Factory, Allahabad, Louis-Théophile Marie Rousselet (1865–68, published 1869–70)
An Indigo Factory, Allahabad, Louis-Théophile Marie Rousselet (1865–68, published 1869–70)

Before having a restoration done

On ethics

Sake Pourers with Bamboo and Bellflowers, Seifū Yohei I (c. 1844–57)
« A serious restorer knows how to decline an intervention they cannot justify. »
Dr. Lucía Ferrer, member of the certification committee

Vocabulary of restoration

Reversibility
Possibility of removing a product without harming the original.
Refixing
Re-adhesion of paint flakes to the support.
Filling
Filling a loss before retouching.
Integration
Retouching that makes a loss less visible without copying the original.

Frequently asked questions

Does OIMAP restore works?

No. It recommends and records; restoration is carried out by a professional of your choice.

Does a restored work lose value?

A documented, ethical restoration preserves value; an undeclared restoration may reduce it.

Does the certificate of authenticity remain valid after restoration?

Yes, if the restoration is declared; it is updated.

Is there any aid?

A protection fund finances certain restorations of local heritage works, on application.

Useful documents

Contacts

The Pyramid of Cestius, Rome, Michiel van Overbeek (c. 1650–80)
The Pyramid of Cestius, Rome, Michiel van Overbeek (c. 1650–80)
Certification DepartmentParis — Headquarters+33 1 00 00 00 00certification@oimap.exampleMonday to Friday, 9 a.m. – 5 p.m.

Have a report drawn up

Portrait of Machtelt Suijs, Maerten van Heemskerck (c. 1540–45)

To find out whether your work needs an intervention, start with an examination.

See the examination
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