Sauna Wood Slats Darkening or Blackening on a Yacht

In yacht saunas, the wood of benches, walls, or slats can darken, blacken, or develop stains. This often indicates that something is not functioning correctly or that the cabin environment is excessively humid. In the marine environment, where humidity, salt, and long periods of inactivity are common, wood deterioration can accelerate. Below are the main causes and recommended solutions to keep your sauna in optimal condition.


1. Humidity and Salt Accumulation in the Sauna Cabin

If a sauna remains off for weeks, marine humidity and salt can penetrate the cabin, causing the wood to become damp, darken, stain, and lose its natural color. To prevent these effects, it is important to ventilate the sauna after each use, turn it on at least once a month for 10–15 minutes, and avoid leaving towels or other damp items inside.

 

2. Insufficient Ventilation

Poor internal air circulation promotes condensation and wood darkening. To ensure adequate ventilation, check that:

  • the lower air intake is unobstructed
  • the upper air outlet is free
  • no slats or panels cover the vents

 

3. Localized Overheating Near the Heater

If the heater is too close to walls or benches, or if stones are positioned incorrectly, heat can blacken nearby areas. This is noticeable when darkened slats appear near the heater or burn marks/brownish areas are visible.

Solution:

  • verify heater placement
  • maintain minimum safe distances from walls and benches
  • improve ventilation around the heater

 

4. Wood Unsuitable for Sauna Use (Common on Yachts)

Some yacht saunas installed by shipyards use soft wood or wood not certified for high temperatures. This can cause rapid color changes, higher absorption of sweat, humidity, and salt, and early darkening of slats. The solution is to replace slats with sauna-specific wood, such as:

  • Abachi
  • Hemlock
  • Cedar
  • Thermally treated poplar

 

5. Cleaning with Unsuitable Products

Using harsh cleaning agents can penetrate the wood and, when heated, cause blackening and unpleasant odors. To avoid these problems, it is essential to use only gentle, sauna-specific detergents and avoid perfumed products, alcohol, or multi-purpose sprays.

 

6. Sweat, Sunscreen, or Cosmetic Residues

On charter yachts, guests often enter the sauna with damp skin, oils, sunscreen, or after-sun products. These can penetrate the wood, causing stains and odors. To prevent damage, it is necessary to:

  • clean gently immediately after each charter
  • lightly sand slats if necessary

 

7. Incorrect Wood Treatment

Never treat sauna slats with protective oils, varnishes, or impregnating agents, as heat can darken the wood and release unpleasant or potentially toxic odors. To restore darkened slats, perform:

  • light sanding with fine-grit sandpaper (180–240 grit)
  • cleaning with a sauna-specific detergent
  • complete drying of the cabin
  • turning on the sauna to remove residual moisture

 

Centro Italia Yachting Technical Assistance and Spare Parts

Contact technical support if sauna slats show:

  • significant blackening
  • burn marks
  • deformation
  • excessive darkening (over 50%) near the heater

These issues may indicate installation or ventilation problems requiring a qualified technician.

For assistance or spare parts, Centro Italia Yachting provides a dedicated service. You can contact the toll-free number 800 931 931 from Italy, or +39 327 612 0605 from abroad. Alternatively, submit a request via the Contact page. A specialized team is always ready to provide fast and professional support.