Hi Guys,

I'm a little curious about the grade of oxalic acid your using. Is it a crystal white powder or does it have a brownish color to it?

We did a job back east a few years back and we got some of the industrial grade oxalic ( brownish in color ) from a local supplier. I was unaware of it at the time but soon learned that the brownish color is because there is iron in the product. As some of you may know, iron, water and wood do not go together, you wind up with iron contamination. This can really screw up your finish.

If your oxalic acid isn't a pure white powder, please let me know, It could help me in answering a lot of questions.

Jim Bilyeu
Exterior Woodcare