Cracking grout

[Gazzer]

Hi sWe, if you look at the Karl Dahm demo on Trade Tilers web site, thats the way I do it, I am not clear about your method, if I run the sponge over the rollers at a 45 deg angle the sponge will only run on one roller, the other side of the sponge is stuck to the handle.
john

:lol::lol::lol:


That made me laugh

I think you will find sWe means rotating the float (sponge side down) and then pushing it over the rollers.
As long as the rollers or roller squeezes the water out of the sponge then its fine. sWe is spot on with technique, most people struggle with a washboy because they dont try to adapt to this technique. Its a wonderful tool when you get it right.

 

[Turkish]

I`ve got a Karl Dahm and as Sir Ramic stated above move the sponge along both rollers flat to squeeze out the water but as you come to the end of the sponge tilt the sponge up by 45` so the very end of the sponge goes across the rollers.

Turkish

 

[grumpygrouter]

I also have a Karl Dahm washboy. I recently bought a couple of new spongeboards - Rubi. The sponges are very good but there is a problem with the board itself. The strengthening ribs of the plastic do not allow surface water to run off easily, you have to have a separate action to pour the water back into the bucket otherwise it spills onto your nice new grout! Very irritating!

 

[sevman]

Dont suppose these tiles were from B&Q? I have the same problem, however I believe the cracking is due to the tiles lifting from the edhesive therefore allowing the tile to move when walked on thus causing the crack in the grout. I am about to lift the whole lot up and start again with a different adhesive.

 

[MICK the Tiler]

Just a few questions on your grouting techniqe.

did you use sanded or non sanded grout (ultra smooth)?

how much of the floor did you grout before washing down?

Did you seal the tiles before or after grouting?

Black grout has a high content of white sand in it (Believe it or not) and using too much water while washing down will wash all of the black oxide pigment out of the grout leaving the white sand at the top of the joint. Also washing the floor down too early before the grout has had time to harden off a bit will also cause this to happen.

If your new to using a washboy only use it when you grout a floor with grey sanded grout to start with this type of grout is far more forgiving to mistakes than black grouts will ever be. The colour will also make a complete mess of your expensive equipment. When doing black I always do it by hand to save my expensive gear.

The cracking may not be all the way through the entire depth of the joint just on the surface the fine white sand will pull back from the edge of the joint once the excess water has had time to evapourate from the surface. Sealing the tiles before grouting will also cause this as there is no bonding capacity left in the grout after all the fines have been washed away through over watering. The sealer will actually repell the water along with some of the fines in the grout hence the surface cracking.

These are just some senarios that could cause the problems outlined. A solution may be a simple matter of re-skimming with black grout and washing off with a damp not wet sponge by hand. Always try a test area first to determine appropriate course of action.

 

[dock]

Sorry to hear of your dilema with the cracking grout.

Unfortunately it may well be down to the substrate prep. as it should be braced sufficiently to provide a stiff, rigid and stable floor FYI;

1 Overlay should be minimum of 18mm screw fixed at max. 300 centres.
2 Fix tiles in at least an S1 adhesive such as Keraquick
3 Grout with a CG2 grout such as Ultracolor Plus (26 colours)
4 Perimeter Moovement Joint and at 6M centres fill with Mapesil AC same colour as grout.

best of luck with remedial works................................hope it goes well

dock