The honed finish is produced in the initial stages of the polishing process taking the surface to a smooth finish but without producing a shine, that is, a matt finish.
On completion of installation, we recommend that a honed natural stone feature walls be sealed with a penetrating sealer, (see attachment or refer to website for list of recommended sealers).
Penetrating sealers do not change the appearance of the material or leave a film on the surface. After application of the sealer any excess sealer residue should be removed by buffing with a white nylon pad. This buffing process will leave the wall with a low sheen which will return to a more matt finish after a short period of exposure to the elements. Generally external feature walls call for minimal maintenance in terms of cleaning; however one may consider periodic cleaning with high pressure water only to remove dust.
As an external surface, some weathering is likely and may result in some fading of the colour, corrosion from acid rain and some veins or fissures may open to some extent becoming more accentuated. The manner in which this occurs varies from one material to another as the structure and behaviour when exposed to the elements is unique to each individual material. The ageing process may be more becoming on some materials, however, if there is a requirement to rejuvenate the general colour and appearance of the stone after some years, one may consider applying an application of a colour enhance sealer, (see attachment or refer to website for list of recommended colour enhance sealers).
If on a masonry background, the substrate should have been waterproofed prior to installation. This will minimize weeping of moisture with impurities from the background, (bricks, render or concrete panels), through to the stone surface resulting in efflorescence. Fresh or loose efflorescence is usually removed easily by high pressure cleaning with water and possibly buffing with a white nylon pad.
If the efflorescence is hard or baked on the surface, removal will require treatment with an acidic cleaner and re surfacing or re honing of the surface, (that is, any acidic cleaner will etch the stone surface).
A safe household option for an acidic cleaner is Apple Cider Vinegar. On some materials some slight etching of the surface may not detract from the overall appearance of the feature wall due to colour, patterning or veining which make the surface more forgiving. If using Apple Cider Vinegar or other acidic cleaner for removal of efflorescence we suggest a trial on a small sample or inconspicuous area to be clear about the impact it will have on the surface.
If the feature wall stone is mechanically fixed, inclusive of cavity then any risk of efflorescence is unlikely.
We recommend that sealing, re surfacing or use of acidic & industrial cleaners for removal of efflorescence be carried out by a recommended sealing contractor or stonemason, (see the attachment or refer to website for list of contractors).