News, Newsletters, August issue Picture framing: irreversible, but preventable
Picture framing: irreversible, but preventable
"Picture framing" is the term used to describe discolouration around the edge of an individual piece of stone, sometimes repeated many times in a single installation. The discolouration creeps in from the edge of each piece of stone, and it looks like a water ring (or a picture frame). Once picture framing occurs it can't be fixed, and can only sometimes be disguised, so it's worth taking the time to prevent. |
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Picture framing inside, on sandstone Picture framing is generally the result of a failure to correctly pre-seal stone before it is laid. Pre-sealing is often completed on site, and usually – at best – is done only on the back and sides of each piece of stone. However picture framing can even occur on stone that has only been surface-sealed after installation. Picture framing occurs when the moisture penetrates through the side of the unsealed stone, leaving a moisture migration line that is visible on the surface. As the colour change takes effect right through the body of the stone, even diamond grinding won’t remove the damage – it will simply expose the exact same picture framing, all the way through the stone. It might sound like an outdoor-only problem, but picture framing can equally occur indoors. If very wet grout is used during the tiling process, the stone will suck the water out of the grout. As well as potentially causing picture framing, this dries the grout and means it can sometimes crack. Picture framing can also be worsened by over-wetting an existing floor, and this can easily occur when excess water is used in day-to-day cleaning. |
And occurring outside, on basalt Picture framing is almost impossible to fix, so the best solution is to disguise the damage. Darkening agents or dyes can achieve this on darker-coloured surfaces, however won’t yield as much of a result on lighter surfaces. It is possible to minimize the occurrence of picture framing by ensuring that porous stone is pre-sealed (on all sides) before it is laid, using a high-grade sealer that will allow re-sealing. Full dip-sealing provides the best results, and is particularly important on high-value stone or outside areas where efflorescence may occur. Using semi-waterproof grout where picture framing is a potential issue will also reduce chances of it occurring. Even stone that hasn’t been pre-sealed is unlikely to suffer from moisture migration if surrounded by a semi-waterproof grout. The best solution is a combination: use a semi-waterproof grout and pre-seal the stone. A small amount of cost at installation can save the cost of replacement if picture framing becomes a problem. Slique can test and pre-seal your stone at our laboratories – contact your local branch if you’d like to discuss this as an option. |
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