hi im after some advice on sand for internal rendering after a dpc, when i did a local dpc course we were told to use a clean washed sand so not to have salts and contaminates in, so ive been using washed river sand from a local merch but they only sell it in 40kg bags and they are doing my head in aswell as my back!!!! is it ok to use plastering sand from tp or b&q ??? thanks si