Do I need to use bleach on this refinish on a garden bench?

[Brian Kent]

Refinishing a bench. A light rain and good light shows the weathered areas as black. I am using scrapers first, then sanding. Should I also use a bleach to clean out the deep grain?

It is white oak, removing 5 year old Epiphanes and refinishing with Epiphanes. I have pictures, but I do not see how to add them to this post.

[Wayne Lomman]

The black could be mould. After you have gotten the old finish off, a good scrub with an acid cleaner destroys the mould and a following clean with bleach will bring it up looking clean. Oxalic acid cleaners should be fairly common and safe enough to use. Cheers

[John TenEyck]

Could be mold but could be decayed wood, too. White oak turns black pretty quickly once the finish is compromised. This is exactly what happened with a black locust bench I finished with Epifanes. I never did find a way to completely kill the black in the deep pores/cracks. I ended up scraping/sanding the old finish back to clean wood and then put on the new one. I did it twice over about 5 years before I smartened up and bought a cover to keep over the bench when I'm not using it. No additional maintenance has since been needed.

John

[Steve Kohn]

Would spraying with Wet-n-Forget help?

[Tom M King]

I put White Oak Board and Board siding on our house, and barn when I built them in 1980. It's never had any kind of coating on it. I pressure wash it about every ten years, and it looks just like it came from the mill. It will go completely black if left long enough between pressure washings.

The first time I ever pressure washed it, I used bleach, and it made the galvanized fasteners bleed stain into the wood. As we have built multiple additions onto the house, I've been pulling off the stained boards, and using them as the first layer, with stainless steel nails these days.

Pressure washing with just water works fine, and is what I've been doing ever since that first time using bleach. Here is some of the original part, that I've never swapped the outer layer, that I just pressure washed last week. Pressure washer is 4.4 gpm at 2500 psi, using 25 degree nozzle. It will take years for it to turn from the silver it will be for several years to black. It all comes right off, down to bare, clean wood.

Boards are vertical instead of like turned picture. This is 40 year old siding in the picture. I paid $100 a thousand for it back then.