Distemper and Soft Distemper in London Period Properties

Distemper in London Period Properties: What Every Owner Should Know

Distemper is the most misunderstood coating in London's historic housing stock. It surfaces regularly when owners of Georgian and Victorian properties start decorating and discover that modern emulsion will not adhere properly, that plaster is coming away with old paint, or that they are looking at a powdery, dusty surface that no amount of preparation seems to fix. Understanding what distemper is and how to handle it correctly prevents expensive mistakes.

What Distemper Is

Distemper is a historical water-based paint made from chalk (whiting) bound with animal hide glue. It was the standard interior wall and ceiling finish in Britain from at least the seventeenth century through to the mid-twentieth century, when emulsion paint became widely available. Almost every Georgian, Victorian, and Edwardian property in London would originally have been decorated in distemper on its interior plaster surfaces.

Soft distemper -- the most common type -- is simply whiting and size (animal glue dissolved in warm water), sometimes with pigment added for colour. It dries to a beautifully flat, chalky finish with a depth of surface quality that modern emulsions struggle to match. It is also water-soluble when rewetted -- which is where most of the problems arise.

Oil-bound distemper (also called washable distemper or oil distemper) adds a small quantity of linseed oil to the formulation, producing a slightly harder film that resists rewetting. This was used in kitchens, bathrooms, and other areas requiring more durable decoration.

Why Distemper Causes Problems with Modern Paint

Soft distemper remains permanently soluble in water. When water-based emulsion paint is applied over it, the water in the emulsion rewets the distemper layer, which loosens from the substrate. The emulsion then cures while sitting on a weakened, powdery surface, and adhesion failures -- peeling, flaking, and patches of paint coming away with the surface -- follow within weeks or months.

This is not a problem with the modern paint. It is a fundamental incompatibility between film-forming modern coatings and a surface that was never designed to be coated over.

How to Identify Distemper

The simplest test is to wet your finger and rub the wall surface firmly. If the surface smears or picks up a chalky residue easily, soft distemper is likely present. Distemper surfaces tend to feel dusty or powdery and have a completely flat, almost velvety appearance. Where multiple redecoration cycles have occurred with distemper, the surface may be very thick and slightly uneven.

In London Georgian and Victorian properties that have not been heavily renovated, distemper can be found on ceilings (where it was used continuously into the 1950s) and on walls, particularly in older parts of buildings that have not been touched since the original decoration.

Options for Dealing with Distemper

Full Removal

The most thorough approach is to remove all distemper back to bare plaster before applying any modern coating. This is done by wetting the surface section by section and scraping. It is time-consuming and messy, and it can disturb lime plaster surfaces -- the plaster beneath needs to be sound and stable before any new paint is applied.

For properties where a full redecoration is planned and high-quality results are wanted, removal is the correct approach. It gives the cleanest substrate and eliminates future adhesion risk entirely.

Consolidation

Where removal is impractical (very large areas, fragile plaster, cost constraints), consolidation can stabilise distemper sufficiently for modern paint to be applied over it. This involves applying a diluted solution of bonding primer or specialist distemper stabiliser, allowing it to penetrate and harden the distemper layer. The result is not as reliable as full removal but is significantly better than painting over untreated distemper.

Specialised products for this purpose include Zinsser Gardz, which is formulated specifically for sealing powdery and chalky surfaces. Multiple coats may be needed on heavy distemper build-up.

Preserving Distemper with New Distemper

Where a period-accurate finish is desired -- in conservation area properties, listed buildings, or where original finishes are being preserved for heritage reasons -- new soft distemper can be applied over old. The products available for this include Earthborn Claypaint (which behaves similarly to soft distemper), Edward Bulmer Distemper, and Craig and Rose Traditional Distemper. These breathe like the original, sit correctly on lime plaster, and produce finishes that look genuinely period.

This is increasingly specified in higher-end London period property restorations, where the intention is authenticity rather than simply a clean white room.

Listed Buildings and Conservation Areas

In London listed buildings or properties subject to Article 4 directions, changing historic distemper finishes to film-forming modern paints may have implications. The use of breathable, vapour-permeable coatings -- including new distemper, limewash, and clay-based paints -- is typically preferred or required on historic lime plaster. We advise on this as part of our service for listed and conservation-area properties.

If you have discovered distemper in a London period property and are unsure of the best approach, we are happy to assess the surfaces and advise on the options during a site visit.