On 2007-08-14 17:27:25 +0100, "No Kidding" idontlikemond@ys said:


"Andy Hall" wrote in message
...
On 2007-08-13 23:47:51 +0100, "The Medway Handyman"
said:

Had two jobs this/last week involving grouting wall tiles, one where I
have
tiled a wall and one where I raked out the old grout on existing tiles.

It's been really hot & humid in sunny Medway this/last week and both
bathrooms have been short on the ventilation front.

In both cases I've noticed that the grout in small areas has dried with
small 'pinholes' in it.

The newly tiled wall should have been dry, tiled on Saturday, grouted
Monday. The raked out grouted wall showed the same symptoms.

Used a proper grout float on both walls, proper grout finisher, different
make of adhesive/grout in each case, both newly purchased. Not seem this
before.

Is it the humidity & temperature that causes this? PITA as I had to
regrout
in both cases to get a good finish.

BTW is there actually any difference between a 'grouting sponge' and a
'sponge' - apart from the price? I cant see any.

I've just completed a tiling job using large format (305mm sq.) limestone
tiles. I went to a lot of trouble contacting the major adhesives
manufacturers and talking to their technical departments. Probably the
two significant ones in terms of coverage of applications are Ardex and
Weber (used to be Howtex).

Ardex were especially helpful in terms of choice of fixing system and
procedures to use and their web site has a lot of useful information for
different applications. I was especially concerned about fixing to
different surfaces - in the same room there are plasterboard, ply,
plaster. Ideally, one should use a different fixing and sometimes
grouting approach for each of these (can be more if it will be a wet
area), but I wasn't going to buy three different sets of materials -
especially when each comes in minimum of 11kg bags. Equally, the
premixed materials that are sold under some of the manufacturer's other
brand labels such as Dunlop are not well suited to the applications I had.

Ardex came up with a solution that could be made to cover the entire
requirement of fixing and grouting by choice of commercial adhesive, admix
and primer and then grout and admix for that part. It also ended up
being the least expensive approach to the complete job. A primer was
used for the plywood to assist bonding to that. The admix for the
adhesive both makes it flexible but also extends working time. The same
was true for the grout. Professional tilers often use faster setting
adhesives because they can work faster or have an assistant doing part of
the work. Often there is a requirement to walk on the tiles fairly soon
after laying.

For the occasional tiler, they told me that short open time can be risky
and that especially in warm conditions can waste a lot of material because
the adhesive has gone off too quickly. Crucially, for grout, the
suggestion was to use a slower setting one and also to seal the tiles
after fixing but before grouting using Lithofin MN Stainstop. For stone
tiles, especially softer ones like limestone, this is critical to avoid
staining, but also significantly reduces absorption of water. I was
warned that rapid drying causes pin holes and potential cracking, as does
mixing to the wrong consistency. I wonder whether ceramic tiles absorb
water through the sides of the tile.

Regarding the grout mixing, it was recommended to proceed slowly and after
the initial addition of powder to water and the first stirring, to allow
the adhesive to slake for a few minutes and then stir again, adjusting
consistency if needed.

I also bought a couple of books. Considering the investment in the
materials and time, I thought that that would be a worthwhile investment.
Of these, the best I found was one called Setting Tile by Michael Byrne.
It's a U.S. book, which results in measurements being in imperial, which
is unfortunate, but the techniques, materials and content are generic.
He gives a large number of hints, tips and methods that come from his own
experiences. For £11.50, it's a good buy.


What was up with "I was warned that rapid drying causes pin holes and
potential cracking, as does mixing to the wrong consistency" instead of
adding all the pretentious waffle?

There's no pretentious waffle - simply some additional information,
which in the context of tiling projects may well be useful.


The OP only wanted to know if humidity & temperature causes pinholes not
your life story.

Were you actually contributing anything or just pricking your own pinholes?