Because the Andy Sandy blocks do not tear or clog like sandpaper they work on any rough surfaces e.g. stone, even Yorkshire stonework. One of our customers renovated all the outside of their cottage!!Renovating garden furniture has never been so easy.Adopt a family and see the difference. HAPPY SANDING !!!TO ORDERemail patdarby@btinternet.comphone 01287 610183or post a cheque for £5.00p + £1.50p postage each to:ANDY SANDY4 BOLTON WAYGUISBOROUGHTS147AL