Yellow Stains

Got called back out to a job due to customer complaining of me leaving yellow stains (shown in photo) on their deck overhang after softwashing. There’s a few more spots but they all look just like the spots in that photo. I have no idea how I could’ve done this or how to remove it. Please help. Thank you all in advance.

(Not sure what material it’s made of)

looks like seepage, and the color is from the wood underneath. just use mix out if a pump up and light mist rinse.

1 Like

What % SH should I hit it with out of the pump up? When I was there I hit it again with the house wash mix then gave it a rinse with a bit of pressure but it only faded it a little.

Try oxalic.

I’ve had that issue before from not rinsing enough. Oxalic fixed it.


i was gonna say it could very well be rust. it didn’t look like much, can it be wiped clean?

I agree with qons. The place I see it at the most are the smoker’s houses, they sit and smoke on the porch all year long. Reminds me of when we cleaned drop ceiling tiles in the 80’s. If you see like 9 ashtrays on the porch, bring a soft brush or clip a towel over a 2’ broom and hit the solid ceilings. Takes maybe 5 extra minutes and no one will call you back, just be careful around the cans and don’t forget the seams/grooves.

1 Like

Thank you. What ratio would you recommend for this?

1 cup of ox to 1 gallon of water. Warm water will dissolve it better.

I’d do a test spot first by wiping a small area with a rag dipped in the solution.