Q: I have old urine stains on my hardwood floors. There is no odour or buckling, just dark marks. When the moisture is high these areas become damp. How do I stop this?
A: If I understand you, during high humidity these old pet stains become damp? I don’t have any clue why that would be. If you want to apply something over these spots to stop odour, I would suggest the Universal Sealer, which is shellac based and made by Zinsser.