Tuesday, 23 February 2016

Dealing with Efflorescence.

You may have seen a white powdery substance on brick and tiles. This is a natural phenomenon called efflorescence. Under certain circumstances, a white powder can form on unglazed terracotta type floor tiles. This is due to soluble salts rising to the surface from the concrete slab. When they dry out on the surface, the remaining salts appear white and powdery.

Efflorescence often occurs in the cement joints of new brickwork or grouting between tiles, especially shortly after they have been laid. Numerous studies have been made around the world to try to determine why it can appear in one location and not another under seemingly identical conditions. The only things that we do know are that it happens when Portland Cement is present and there is no real solution for it. Efflorescence does clear up over time unless there is an ongoing issue with rising damp from the substrate. It is defined as the 'migration of soluble salts.'

This is not due to substandard tiles, adhesives, or grout; and generally there is nothing to worry about.

The only real solution is to brush the grout with a stiff bristled brush and vacuum away. Commercial efflorescence removers are also available, these are generally acid based.

Repeat this from time to time and generally, it should eventually stop recurring.
Some people advocate brushing the salts away and then applying a penetrating tile sealer. While these are great products, and are worth using because they will keep your grout and tile clean and seal out dirt, these products generally won't stop efflorescence.

In most cases, penetrating sealer applied with a lambswool applicator will help as it works by allowing vapour to transfer through to the surface, but not moisture. It allows the tile to 'breathe' and can reduce the problem, although it is not guaranteed to always work, especially in outdoor areas.

You can also wash with a 50/50 mix of water and phosphoric acid. Leave the solution on the tiles for two minutes, then thoroughly wash off with clean water.
Always take care with stone (marble, granite, and sandstone) and acid sensitive products. First test in an inconspicuous area.

Tuesday, 16 February 2016

The Curious Case of the Gridlines on Tiles.

We encountered a very curious case recently which mystified us for days but we are pleased that it has now been solved after some careful detective work.
A commercial space had been tiled with large white porcelain tiles and it was reported that the tiles had discoloured and that white gridlines had appeared.

Now as I wrote last week, tile just don't darken or fade. Almost the only explanation for the darkening could be moisture seeping into the tiles. However this seemed very unlikely as porcelain has a very low water absorption (<0,5%).

The appearance of the white gridlines was even more mysterious. At first we could only conjecture that somehow moisture had entered the tiles from below and some form of efflorescence was taking place, transporting dissolved salts through the tile body from below replicating the grid pattern on the underside of the tile. As it turns out however, we were entirely wrong!

When we examined the tiles on site we discovered firstly that the tiles were simply dirty and that explained the dark patches. The floor had been cleaned but not rinsed. Over time soap residue had built up and attracted dirt which appeared as darker patches on the tile. This in turn led to the faint white gridlines to become visible. Previously the gridlines were invisible against the white surface of the tile.

But where did the gridlines come from and why did only some tiles show this pattern? We found some boxes of spare tiles around the back.

I mentioned that the tiles were larger than normal. As a result they were packed three to a carton rather than four. As you can see two tiles were packed face to face but the third tile's face was packed against the grid-patterned underside of another tile.

I'm sure you will have noticed a fine white powder on the underside of tiles before. This is a release agent applied to unfired tiles to ensure they don't stick to the rollers in the kiln. This powder had been transferred to the face of every third tile during transportation!

So some simple solutions. Firstly, clean the tiles with heavy duty cleaning agent to remove the white deposits and properly clean and rinse in future. Secondly alert the factory of the problem and pack the tiles with foam dividers or at least with the faces turned away from the base.

Although we were wrong about efflorescence, I'll write in more detail about that problem next week.

Tuesday, 9 February 2016

My tiles are becoming darker.

Quite simply... No, they're not. Tiles cannot change colour. Tiles are an inert product like stone. They do not fade in sunlight and neither can they tan, or turn a darker shade.
If a tile is contact with water however, it will absorb water. When the body or biscuit of the tile absorbs water it will appear darker. All tiles absorb moisture to some degree, depending on the type of clay biscuit. And then, just like wet chalk, or a sponge, the biscuit will appear to be a darker colour or shade. Even porcelain will absorb water, by definition less than 0,5% of water by volume. If the glaze on a wet tile is white or a very light colour it tends to be translucent or see-through. The darker background biscuit will then make the tile look darker than other dry tiles.

Water damage that originally came from above but then seeped below the tiles and caused discolouration and in this case also caused the tiles to lift.

In extreme cases, even when the tile has completely dried out, the biscuit can be stained by impurities that have entered with the water and the colour of the tile will appear to have changed.
Water absorption is really the only way that a tile can appear to have changed colour. If water has penetrated behind the tile, or is caught behind the tile it will soak into the biscuit of the tile. Water can penetrate behind the tile through holes in the grout, missing grout, or poorly applied silicone joints. Especially, if there is a partly blocked drain and slow draining waste and any silicone joints in the internal corners are not intact. This is particularly common in wet areas like showers.

It is not a problem with the tile, but the installation, or perhaps a serious water leak.
If you notice that the tiles in your wet area, especially in the shower recess have changed to a darker colour, the situation needs attention as soon as possible. It is an indication of a problem that can cause long term structural damage if left unattended. Call a plumber to test for a leak in the water supply system.
Check for any obvious visual faults or weak points in the grouting and silicone joints. If it appears suspect, remove the grout in the affected areas. Dry the tiles out slowly, using a fan heater on low. This should bring them back to normal appearance. Regrout the tiles using grout mixed with a 'booster.' Apply silicone to all corners in the shower.

It can also occur in apparently dry areas. If the tiles were laid before the concrete underfloor was dry and properly cured moisture will percolate upward into the tile body. This will cause the tiles to look darker. In fact they are simply waterlogged. Even a small amount of water can have this effect, especially with very pale tiles.

Tuesday, 2 February 2016

Flint - New large format porcelain.

This is 'Flint' a true porcelain with a measured water absorption of 0,28%, well below the 0,5% standard. Available in large format 120 x 60cm (4' x 2') and square 60 x 60.

The colours shown above are a pretty accurate reflection of the shades it's available in. This photo taken in our showroom this morning. It really is a stunning tile with a very modern industrial raw concrete feel that can work in a modern apartment, a boutique or even a commercial space like a restaurant.

Below is a detail shot showing the face design and variation. It's a hi-res inkjet tile so it comes in several faces.

For enquiries and prices contact

Visit our recently updated KREM website to see other new inkjet designs.