Scratching sills is something I've been checking recently, after all we don't even see above ground floor now!
I was cleaning ground floor of a property a few weeks back and I noticed the sills were badly scratched, it worried me, I thought "is that the damage I'm doing?" I've been wfp ing this particular property for almost 4 years, so I thought it must be me.
Here is what I did: When I'd finished the whole place I got my brush head (Gardiners dualtrim supalite) and rubbed up and down the sill with the stock in my hand pressing harder than I ever would when cleaning, guess what? No scratching at all! So I went back round drying all the sills so I could look more closely, it was a sunny day so a good opportunity.
Here's my conclusion: Unless they are top quality upvc windows then they were probably scratched already, either in handling, inferior upvc, or installation. It's just that the scratches themselves were so fine and the products so clean and new that they were never noticed. But over a period of time, years, the dirt gets in, and the scratches appear. If they really upset someone they can easily be removed with a pvc cleaner, but I'm not offering...
