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.

--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257