I did ours sometime ago using washing up liquid solution and came up almost like new, to avoid damage it really needs to be a 2 person job, one doing the sponging and the other outside holding something suitably flat and the right size so you don't tear the mesh and also to give you something to rub against, tried doing it on my own and was a complete waste of time, time consuming but well worth the effort or it was on our caravan.
BP
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