I have a large internal surface area of riven blue lias flags laid c17th century. There are some which have been poorly pointed with liberal use of cement which is now crumbling. Any advice on removal of the cement pointing and repointing (using what?) appreciated.
There are others which have cement smears virtually covering the entire flag, and/or residue of rubber carpet underlay and adhesive. Any advice on chemical/manual removal also appreciated!
Finally, what would be your advice on sealing/polishing said flags once this has been done? The flags, as far as I can gather without lifting, are laid direct to soil.
All advice gratefully received!
Wurzelwolf
Internal flags - Re-pointing cleaning & sealing/polishing
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Tony McC
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I'm not sure what type of rock these Lias flags might be. When I was studying rocks at Uni, Lias was a geological period and a type of clay laid down in those times. The reason for me waffling on is that, if these are a limestone or calcareous stone, then using a cement-cleaner could do more harm than good.
The best way to cut out the existing pointing is to use a nangle grinder with either a stone cutting disc or a mortar-raking disc. It's messy; it's dusty; it's a pain in the arse, but it's quicker than owt else.
Cement stains are typically removed using an acid-based cleaner, but, as I said, the acid reacts with calcium carbonate and so you really must test it on a discreet area first, before sploshing it all over your flags. You can buy the acid at Builders' Merchants, but check the dilution. Ideally, use 2-5% strength, diluting with clean water if necessary.
The rubber underlay is more problematic. I'm not sure what would be best, but if there's any of it left after the acid treatment, then maybe white spirit would help loosen its grip on the flags.
As for sealing, one of the most popular treatments for internal stone flagged floors is Golvpolish from Hagesan. You can buy it at Topps Tiles. It's a waxy joillop that's rubbed into the surface and it can be re-applied as and when required. It brings out the colour, but also protects the surface to some degree from minor stains. If you wanted a more heavy duty sealant, then MN StainStop, also from Hagesan and available from the same outlets) may be more to your liking.
The best way to cut out the existing pointing is to use a nangle grinder with either a stone cutting disc or a mortar-raking disc. It's messy; it's dusty; it's a pain in the arse, but it's quicker than owt else.
Cement stains are typically removed using an acid-based cleaner, but, as I said, the acid reacts with calcium carbonate and so you really must test it on a discreet area first, before sploshing it all over your flags. You can buy the acid at Builders' Merchants, but check the dilution. Ideally, use 2-5% strength, diluting with clean water if necessary.
The rubber underlay is more problematic. I'm not sure what would be best, but if there's any of it left after the acid treatment, then maybe white spirit would help loosen its grip on the flags.
As for sealing, one of the most popular treatments for internal stone flagged floors is Golvpolish from Hagesan. You can buy it at Topps Tiles. It's a waxy joillop that's rubbed into the surface and it can be re-applied as and when required. It brings out the colour, but also protects the surface to some degree from minor stains. If you wanted a more heavy duty sealant, then MN StainStop, also from Hagesan and available from the same outlets) may be more to your liking.
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