When do you recommend to use a base coat or primer?
For Interior Use
Osmo Wood Protector is recommended for woods prone to moisture, usually in bathrooms or kitchens. It is not necessary to use on ingredient-rich hardwood species.
For Exterior Use
Osmo WR Base Coat is recommended for exterior coniferous wood species such as Pine or Spruce to deeply impregnate the wood and provide increased water protection. In addition it is recommended for use on all other surfaces prone to algae, fungi and mildew growth.