White barns and fences aren't for aesthetics. Lime whitewash is one of the most practical coatings ever invented.
Recipe
Slaked lime — 5 kg. Water — 15–20 liters. Salt — 1 kg (for durability). Mix to thin yogurt consistency. Let sit 24 hours.
Properties
Antiseptic. pH 12–13 kills bacteria, fungus, mold. The Amish whitewash cowsheds and chicken coops — disinfection, not decoration.
Reflects heat. A white surface reflects up to 80% of solar radiation. Inside a whitewashed barn it's 5–8°C cooler in summer.
Breathable. Unlike paint, whitewash doesn't seal wood. Moisture escapes, preventing rot.
Application
Large brush or sprayer. 2–3 coats with drying time. Each coat looks transparent when wet — dries white. Dry weather, 5°C and above.
Cost
A 25 kg bag of lime — $10–15. Covers 100–150 m². Paint — $40 per 10 liters. Refresh every 1–2 years — 20 minutes of work.