Picture Framing
The term,’ picture framing’ is used to describe the visual effect of staining around the edges of some types of paving, especially sawn natural materials including granite. It appears as a damp patch around the edges, and is caused by self-hardening pointing mixes containing resin.
These stains are not permanent, and require no cleaning, as they will reduce with weathering. Some paving slabs may require pre-sealing, especially around the edges, depending on the manufactures specification prior to laying.
A second type of picture framing occurs when bonding mortar has not been fully applied to the back of the paving slab, leaving an uncoated border around the perimeter. This type of picture framing is again, prolific on granite as well as sandstone. Whilst this is similar in appearance to reflective staining (see Reflective Staining) it will require a full lift and relay of the paving slabs.
When applying exterior flexible grouts, often used with porcelain, should the grout not be cleaned off the face of the paving slab correctly and properly, this can leave a ‘picture frame’ of grout. This type of staining may be cleaned with a haze remover.
Photo credit – Global Stone Ltd.
