Our South-facing pergola was originally stained with a white Cabot oil based solid stain then re-stained years later. Eventually the stain started flaking off and we had a bad mildew problem. We have now sanded, treated with Concrobium to kill mold (which is already beginning to return), and will be using a mold stain remover (hydrogen peroxide, ph adjustor, etc). There are still some vestiges of white in knotholes and crevices that have resisted sanding and stripping efforts but we don't really mind them and would probably like to keep the pergola close to the color it is now - a light wood tone. Our main priority is not to create a maintenance nightmare - we can tolerate something fading gently but need to get some years out of this job. Is there a semi-transparent or other product that fills the bill and would help to prevent mildew? We already tested a dark, semi-solid, and that looks bad over the white. Also, after all these steps, do we need to still use a deck cleaner and brightener or can we move right into staining? TIA.
A deck cleaner and would brightener will help the stain to penetrate better. As for a stain, look at a penetrating water-based stain to help with your mildew issues. Restore A Deck Brand or Defy Extreme.
The white solid stain will show through unless you remove it all.
@administrator Thank you. I'm seeing good reviews for Defy Extreme. But do I need to apply two coats with that product?
@administrator After yet more staining and stripping, there are tiny vestiges of the white solid stain in some crevices/knotholes in the pergola. It is barely noticeable, so I'm not worried about the aesthetics, but will that caused the water based stain to fail? Or might it just look imperfect in those spots?
Depends on how much. If a tiny amount, it should be fine. If large patches (inch or larger) you may have issues.