Hello and thanks for reading.
Does anyone know a product which will remove the rust from a very old old internal flagstone.
It's from where an earth rod rotted away? Pic attached.
Many thanks for any help.
I would try bleach just on the rusty coloured area. To be honest it looks to me as if the discolouration has permeated into the stone. Also if there is any metal left in there then even if you do manage to get rid of the discolouration it will come back. There are other products you could try such as patio/ drive cleaners but I haven't much success with those, (oil on my block drive). I eventually got that off using a wire brush on a grinder. I had to dig quite deep though as that had penetrated the stone.
It has probably soaked in. Bleach and ordinary cleaners won't work. Bleach may later turn to yellow stain. There are special acid cleaners that remove rust stains, but if your flags are limestone, will dissolve them. You could try scuffing the surface with a small wire brush, such as the brass ones used for suede shoes, which will abrade deposits off the surface.
Don't use a steel brush or wire wool, because they leave iron particles that cause more rust staining in future.
If you fill in the hole with sand and cement mortar, you can let it smudge over the stain and it may hide it.
Stone flags can also be turned over, but the other side may be no better. If they are all the same size you can swap them around