This ‘flaking’ of some slates is perfectly normal, and should settle down after a while (once all the loose/friable material has come away). Slates come in all sorts of colours, and in many viarieties also, some much younger (geologically speaking) than others. Slates are metamorphic rocks, that means they ‘were’ somthing else before being changed (morphed) into slate. Basically most slates began as a sedimentary rock, laid down in layers (this layering of deposits is important in the formation of layers that can later flake away) of fine-grained materieral like clay, silt and mud etc. These sedimenatary rocks are then subjected to pressure and heat are compressed toghether. This compression, and folding and heat can cause things to break-down and or fuse, and also change and some minerals form cyrstals . This process takes time, lots of it, the longer the time taken (the older the slate) the less likely it will be flakey and have loose layers at the surface. Some of the more colourful slates I have seen coming from Africa can be quite flaky. Unless your slate is really friable, and almost more like a shale or mudstone than a slate, then once the loose parts have come away you should see the stone settle down.

If it is rain water causing the delamination, then I would think the the stone is very soft and have easily split cleavage planes, the expansion and contraction of the slate as it gets wet, and dries out etc, along with extreme changes in temperature could have an ongoing weakening effect. Sealing the slates with a waterrepelling sealer will definatley help but it may not stop it altogether,

My gut feeling is that if you cut-out the worst ones and replace (if they are that bad) and clean and seal them, you should see less of this happening.

Hope his helps

Ian

If you are asking, will a slate wal and floor be harder to keep clean than a glazed white tile, then yes, it could be, but should not be a major problem.

Sealing the slate is recommended as it will make the surface of the slate easier to keep clean. However, keeping the grout clean and like new has more to do with good management of the moisture in the shower area. A sealer will help keep contaminants at the surface, of both the grout and the stone, go for a good premium imprgnating sealer. THis will help reduce the amount of moisture able to get into the grout. ON top of this clean the tiles and grout reularly and also dry them down periodically, like once a week for sure. Doing this will keep moisture and contamination under control.

Not sure if I answered your question so let me know if not

Ian