This rust remover was a game changer for me and Initially I only ordered 1Ltr as I only had a few rust spots. When I applied it to the rust spots and left it a while, after washing it off the slabs were two colours. Where the rust remover was applied the slabs were like brand new so it became obvious that all my salads had rust contamination probably from lawn fertiliser. From that point on I had to coat the whole of each slab so the 1 Ltr bottle didn’t go far so I ordered 4 more, I did try another product on next day delivery from Amazon but it wasn’t any good. This rust remover has brought my Kota Blue Limestone back to its original colour and I’m thrilled. It’s been expensive cleaning and sealing it but it was my fault for not doing it properly 5 years ago.