1st stucco house, great - except a residual streak?

Just did my first large face on stucco and had a bit of a learning curve but in the end, I think it came out great, except one thing. I first used about a 4% SH solution which cleaned some but not all of the black mold. Some areas it didn’t even flinch it. Then applied a 6+% solution to the very difficult areas cleaned up all organics. I just hate that there is a streak down the front in front of the window. The homeowner was very pleased. The streak is NOT organic. I did a test spot on the stucco with some OA, dwelled and then rinsed. It seamed, at first, not to have a signifcant affect on color, however, after everything dried there was a noticable lightening to me. I was glad to have decided to call it a day (which was long).

I thought that it would be residual iron oxide from the atmosphere collecting as the water concentrated/consistently ran down from the window. That is why I had tested OA. What do you all think that is. What are your suggestions on cleaning that streak? Would you then just have to clean the whole face to have even coloring/shading if applying a chem? Thanks for your advice as always.

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Looks good. That streak is from water draining across the surface over the years. It’s probably oxidized hence the color difference. You could try some One Restore to bring it back around but I’ve never used that stuff on Stucco.

I Second trying the OneRestore. I’ve used it on about every surface, my go to for stains.

It could also be rubber from deteriorating seals, or the result of wear and tear of the opening and closing of windows.
I need to get me some one restore to keep on hand, plus some double eagle, groundkeeper and prosoco products.