We have a gorgeous Bath stone cottage with very old windows at the front. At a distance the windows just look a bit tired but up close whoever painted them last did a really poor job - black masonry paint has been applied to the stone mullions really sloppily often going 'over the lines' etc. I can paint over the existing black paint no problem but can't work out how to remove the brush strokes which are in the wrong place. I had a quick go at sanding and made no impact at all - wondering if there's anything I can do myself to strip it back or if I need to wait until we can afford to get it sandblasted? Any advice or experience would be very welcome!