Cracking grout

[Gazzer]

I think that would be the cause of the Efflorescence then. The washboy takes getting use to, i made the same mistakes when i first used one. Sponges seem better if left in water for a few hours to pre soak IMO. It makes the sponges easier to wring out when running over the rollers.

 

[DHTiling]

Most of all john you will need to address the cracking as well......

Was there much movement in the floor before you sheeted it..?..

Don't want you raking the grout out if it will happen again.....You could try a stronger latex grout mix but you need to determine how much deflection there was .....thats why you should have maybe used a thicker sub-floor........

 

[tileman]

There was some movement, but I don't feel that is the problem, I think it's to do with the washboy and me, do I need to rake out the joints or just go over them again.
I will stay clear of the Granfix Ultimateflex in future, it stick like hell to everything.

 

[sWe]

Hi Dave,
Joint 4mm.
I haven't used the washboy a lot for the reason below.
Yes I used a wash boy on this job, it is a Karl Damm, I run the sponge over the rollers many times (as per the instructions)and also try to force the water out with my hands but cannot get the sponge as dry as I think it should be, always water going into joints.
I was doing a floor today and changed to a new sponge and that was better, but still not good.
john

It's either a really bad sponge, or it's your technique.

I've got a link to a grouting guide I wrote in my signature. I couldn't be arsed to go out and fetch my washboy, so I drew a picture on how you're supposed to get rid of the last bit of water in the sponge.

Look at the pic. Place the sponge float the same postition, and then squeese it down on the rollers while tilting the float up to a 45 degree angle. Repeat on the other side of the sponge. With new sponges you generally only need to do this once. With older, worn sponges, you might have to repeat a few times.

If this doesn't work, it's a really bad sponge.

If done properly, this technique will result in the sponge being only damp. There will be not be any excess water, at all.

 

[tileman]

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

 

[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.