How to paint a wine cellar properly: specification, hygiene and taint risk

A working cellar is one of the harshest interiors in South African property, and almost nothing about it resembles the rooms trade paint is designed for. Surfaces sit cold for months. Humidity stays high in barrel halls all year. Tanks chill the air around them so condensation forms on walls and ceilings and simply stays there. Floors and walls are washed down with hot water and with caustic and acid cleaning agents. Then, during ferment, the room fills with carbon dioxide and the smell of fruit, and the air moves in ways nobody planned for.

Put standard interior PVA into that room and it will not last two seasons. It peels above the tanks first, because that is where condensation collects. It grows mould in the corners, because the film cannot be scrubbed. And it comes off in sheets where the wall is an old solid one without a damp course, because moisture moving out through the plaster has nowhere to go.

Wine takes up aroma from the air around it. That is the whole basis of cellar hygiene, and it is why a coating decision inside a cellar is a wine quality decision, not a decorating one. Strong smelling solvent-borne products, slow curing systems and anything still off-gassing when a tank is filled or a barrel is topped are a genuine risk to the product in the room.

This is where cellar-specific ranges matter. Sabre Paints, a Cape Town manufacturer, publishes a wine industry range for cellars and wine storage facilities and states that those products have been tested and approved by Thales Services as safe for use in a wine cellar or wine storage facility. Williams & Co has no relationship with Sabre and is not an applicator for them. We point at it because it is the clearest published example of what a cellar specification should be able to show: documentation, not assurance.

Ask one question before any coating goes into a cellar: what does the manufacturer publish about using this product around wine? If the answer is a shrug, that is your answer.

• Cellar walls in wash-down zones: a washable, hygienic, low-odour water-based system over a primer suited to the substrate, built to take repeated cleaning rather than just to look clean.
• Ceilings and soffits above tanks: the same washable system, specified with condensation in mind, because this is where failure starts on nearly every cellar we survey.
• Old solid lime plastered walls: a breathable system. These walls have always managed moisture by evaporating it, and a low-permeability film traps it, blisters off and brings salts to the surface.
• Barrel halls and maturation rooms: washable and mould resistant, with attention to ventilation and to any moisture entering the structure from outside.
• Corridors, tunnels and thresholds: check for water entering the building before coating anything. Painting the inside of a wall that is being fed from outside is money spent twice.
• Cellar floors: a separate trade. Trafficked floor systems have their own products, their own preparation and their own risks, and a wall contractor should say so.

1. 1Strip back every failed, flaking and mouldy coating. Painting over a lifting film simply moves the failure date.
2. 2Fungicidal wash and full rinse, then allow the surface to dry to a measurable point rather than to a guess.
3. 3Repair cracks, patch plaster and seal open joints, especially at wall-to-ceiling junctions where condensation runs.
4. 4Prime to suit the substrate, not to suit the price. Old plaster, new plaster, fibre cement and steel all want different primers.
5. 5Apply the specified number of coats at the specified build. A thinned coat in a wash-down room is not a saving.
6. 6Ventilate and allow full cure before the room goes back into production. A soft film in a washed cellar fails within the season.

In the Durbanville valley the calendar decides the job. Nobody should be preparing walls during ferment, and no cellar master wants a contractor in the building during bottling. The window that works is usually after bottling and well before the next harvest, with enough slack that cure time is not the thing that gets compressed when it rains.

Phasing also lets the spend be split. Walls and ceilings in one season, corridors and outbuildings in the next, one specification held across all of them so the cellar does not end up looking like three different repaint eras.

• Measured areas per surface, not a single lump figure.
• The wash and cleaning regime the coating has to survive, stated as a fact of the job.
• The named primer, the named topcoat, the sheen and the number of coats.
• What the manufacturer publishes about use in a cellar or wine storage facility.
• Where the coating is breathable, and why that surface needs it.
• Any water ingress work, quoted as its own separate line.
• Protection of tanks, lines, barrels and floors, and who moves what.
• Ventilation and cure time before the room returns to use.
• The dates, agreed against harvest, ferment, bottling and functions.

A quote that will not commit those points in writing is not a cheaper quote. It is a smaller job with the risk left on your side of the table.