On Sat, 24 Oct 2009 12:55:32 +0100, Bill wrote:

Use dilute phosphoric acid, which is all Kurust is, to treat the
rusty
areas with, first.

There is 85% 125ml available on Ebay but this is way outside my comfort
zone. Where as Kurust maybe out side my finances for the amount
required!

Today bought some HG "Cement grout film remover" 1l for £8.43 this
according to the Safety Data Sheet is 15 - 30% Phosphoric Acid. For
it's intended use you dilute 10:1 with water.

http://www.homecareessentials.co.uk/...g/Cement_.html

--
Cheers
Dave.