how to age a mirror with limescale remover and old paper
first take the mirror out of its frame, and put it on newspaper or anything you want to stop making a mess.
then use nail varnish remover and a sponge and rub the back of the mirror this removes the paint, then if you use limescale remover or strong oven cleaner and leave on for a few minutes and rub it again with the sponge it will remove the silver mirror part off the glass, then you can use old newspaper or music sheet paper to back the mirror with, i used an image from graphic fairy. i used spray glue to stick it to the back of the mirror. this made the page look old.