Hi. I have a few exterior portakabin cleans to do. They are apparently wrapped in vinyl, with black streaks showing on the predominantly white background
I did a test area with wfp after applying a bit of soap and water, which is what the customer asked for, but the streaks were still there. Im a bit wary of damaging the vinyl using the wrong stuff (pressure washing is not an option)
Much obliged if anyone can help me out.