Can I apply new putty over old putty that is rock hard and has been overpainted without stripping out the old putty on Bay Window Mullions??
You can but the putty will not adhere properly. It is good practice to remove old putty first.
Sharp implement at least scrap of paint.
Make sure you apply a layer of new putty
So long as the old putty is secure it should be fine
Hi no you need to remove old putty if you put new putty over the old it will not bond
Yes you can use new putty over old
Sharp chisel and chip old putty off ( new putty won’t bond to old hard putty )