Limewash and whitewash

Overview

Limewash is slaked lime (calcium hydroxide) or chalk (calcium carbonate) in water. Wikipedia says it cures by carbonation as it absorbs carbon dioxide, is compatible with masonry because it is absorbed and hardens, has low opacity at first, needs damping down before application, and is mildly antibacterial. Whitewash is the traditional name.

The sources checked document limewash for masonry. Romabio's Classico Limewash is for absorbent, unpainted brick, stone and masonry; use on wood is not a documented use in anything reviewed here. If you want a white, lime-like look on wood, use Liming wax and cerusing on open-grained wood, or thin white paint (pickling, per Fine Woodworking), or Milk paint.

Pros

• Absorbed by masonry and hardens in place (Wikipedia).
• Low VOC claims (maker).
• Dilute 50 to 100% with water; brush or spray; one coat (Romabio).

Cons

• Wood is not a documented substrate.
• Caustic wet: calcium hydroxide.
• Low opacity at first; may need several coats.

Suitability

Brick, stone, plaster. For woodwork see the alternatives above. See White oak for the open-grained wood that takes liming wax.

Coats and application

1. Dampen the surface (Wikipedia, Romabio).
2. Dilute 50 to 100% (Romabio).
3. Brush or spray; one coat.

Compatibility

Only absorbent masonry per sources. Not compared on wood.

Care and repair

Reapply as needed.

Safety and environment

NIOSH: calcium hydroxide REL TWA 5 mg/m3; OSHA PEL 15 mg/m3 total, 5 respirable. Eye and skin burns and respiratory irritation; eyewash and quick drench. Absorbs CO2 to form calcium carbonate. Incompatible with maleic anhydride, phosphorus and nitroparaffins.

Related

• Liming wax and cerusing
• Milk paint
• Chalk paint