In this regular column, Consultant Barry Hunt answers reader enquiries. If you have a question, email it to: [email protected] marked for Barry’s attention

Q: A limestone shower tray has become slippery, what can I do to make it safe again?

I never want to discourage the use of stone but the selection of limestone for a shower tray must be regarded as entailing a labour of love.

There are a variety of issues that it may not be possible to overcome and one or more of these will almost certainly have caused the shower tray to become slippery.

Limestones, even those classified as ‘hard’ due to their low porosity, soak up moisture and react with the great variety of lotions and potions we subject our bodies to. Then there is the problem of the chemicals used for cleaning the shower.

There is a belief that applying surface treatments to stone that reduce the ingress of moisture can resolve many of the problems faced, but in a shower even the most painstaking application of such treatments and subsequent maintenance may still be insufficient.

A stone treatment may even be a significant factor in making a shower tray slippery.

Some of the most widely used and effective stone treatments are based on the silicone group of materials, which can be susceptible to attack from detergents.

Showers are frequently wetted and often remain warm for long periods. This promotes the growth of fungi, bacteria and other microscopic beasts, which can find the organic base of the stone treatments a smorgasbord of nutrients. They can strip away the protection and leave staining in its place.

Sealing a limestone with resin so there is no pore space can alter its appearance and reduce slip resistance to an unacceptable level. And the limestone will still be free to react with anything acidic, rapidly altering its appearance as it begins to dissolve away to leave the inert resin standing proud.

Limestone is relatively soft and scratches easily, so you cannot use abrasives to remove deposits. It is prone to attack from anything acidic, such as descalers (which no amount of treatment can prevent), so you cannot dissolve deposits away.

If you live in a hard water area, one of the few things you can do to minimise such problems is soften the water before it comes out the showerhead.

Texturing the stone can improve its slip resistance, but it can also harbour dirt and residues, making cleaning more difficult. The porosity of limestone will worsen this problem and eventually slip resistance begins to reduce despite the texture of the surface.

If you have the time, good funding and are a glutton for punishment, the limestone could be re-finished in situ.

However, this would have to be repeated on a regular basis and other problems may arise from dusts released or insufficient stone available for the process to be repeated too many times. Thus I really could not recommend this as a sensible option.

What this problem boils down to is the selection of a not very appropriate material in the first instance and then a design that has not minimised the potential problems such a choice has created.

The best option would be to have the limestone of choice given a macroscopic texture such as grooves or raised dimples that continue to provide sufficient slip resistance regardless of how slippery the main body of stone becomes.

Always have a chamois leather or other highly absorbent cloth to hand to wipe down the shower after each use. Regularly use a plastic bristle brush to remove any other residues that may be building up. Use a copper wire brush carefully to remove deposits, which should not scratch the stone.