Help - Tile adhesive not set

[scubapete]

Hi,

Can you tell me if I've messed this up, please?

Tiled one wall of the bathroom last night, finished about 9pm. I randomly put mosaic tiles in amongst the normal cermaics.

This morning decided one of the mosaics looked rubbish and I went to cut it out. I thought this would be difficult as the adhesive would have set.

Wrong! It just popped off and the adhesive was a little powdery when I scraped it off.

Is this normal? Does it take longer than 10 hours to dry and set? (I really hope so).

Background. I took the old tiles off and a plasterer 'patched' up the wall when he was skimming some ceilings. I didn't PVA amd the adhesive is Unibond shower/wet room 5 star waterproof stuff.

 

[Jasonb]

Mosaics are not as absorbant as ceramics so the adhesive will take longer to set, most readymixed will be damp but firm after the amount of time you say. Next time use a powdered adhesive like BAL mosaic fix.

If you have had to put the adhesive on thickly where the mosaics are thinner, thats not a good idea with readymix as it will never set correctly if too thick.

Jason

 

[scubapete]

The mosaic tiles I got are 12 x 12 glass blocks (6mm deep). I cut them down to 8 x 4 to match the brick ceramic tile I'm using.

I layered the adhesive on too thickly for the first few rows and have replaced the affected mosaics with a tin layer of adhesive.

Should I reapply all the other ceramic tiles in these few rows also?

I was following the instructions and applying a 3mm (give or take) layer as its around the shower end of the bath.

Is there a rule of thumb for applying grout when using ready mix adhesive? 24 hours? 48 hours?

 

[Jasonb]

At least 24hrs

Jason

 

[grrinc]

Ready mixed adhesives tend to take a lot longer I find. Especially in the colder weather and with cerain tiles. We removed a flawed tile a while back and it the adhesive was still a bit stodgy after 2 days.

 

[scubapete]

Thanks all,

(Sorry for the length of this post)

I put the tiles up on Fri/Sat and haven't yet grouted (doing lots of plumbing work) so giving it plenty of time to set properly.

I had another mosaic incident on Sunday morning. I was scraping a little bit of dried adhesive out from between the glass blocks and it came loose again as before.

This time though, it was on a section of wall that had previously been painted (looked like that shiny bathroom wall emulsion). I'd scored into the paint pretty comprehensively with a stanley knife and also run a chisel over it to make sure it was scruffed up. When I scraped the adhesive off to reset the tile, the entire layer of paint came off also.

Now, either this is totally normal or I've discovered the easiest method of paint removal known to man.

The same thing must have happened under all the other tiles on that wall. Is it effectively like spreading adhesive on a clean flat wall, then rubbing a load of dirt into it, then fixing the tile? i.e. Are the tiles likely to drop off at some random time in the future? Incidentally this is the wall at the tap end of the bath where the power shower will be....

 

[mountford]

What adhesive did you say you have a used a bucket or powder adhesive?

If you have scored the wall you should have used a primer like BAL apd (this is is if you are using a powder adhesive or a bucket adhesive with out a self primer)

The ideal adhesive as said in a post before is BAL mosaic fix great stuff to work with and its brilliant white.

Never use PVA when tiling as you are creating a very weak substarte to tile to. Remeber when you were at school ( I can just about remeber that far back ) and you used PVA with newspaper, when the PVA had dried on your hands you could pick the PVA off in strips from your fingures, thats what you are doing when you apply PVA to a wall and use for tiling. Just something to think about.

 

[scubapete]

I didn't PVA anything as I had read a very articulate post on here explaining exactly what you just said.

Unfortunately, I didn't read (until it was too late) the sticky about what adhesives to use etc etc and so made my first mistake...

When I was down b&q getting the tiles I just picked up a big tub of 5* rated waterproof ready mixed Unibond wall tile combined adhesive & grout.

 

[mountford]

That was your other mistake never use a adhesive and grout in one. One product cant do 2 jobs and also never trust a big store like that, always go to a tile shop as this is what they are trained in.

If you are doing a bathroom you need a class AA adhesive which is water resistant. This is where some people get confused Class B adhesive is for dry areas as if water comes in to contact with it then the water will break the adhesive down, Class AA is water resistant which means water can still pass through it but wont break it down.

 

[scubapete]

Ok, my heart has sunk and my shoulders have slumped, but this was my first time so live and learn.

If I grout with some proper recommended BAL and then just cross my fingers, what is likely to happen? Will tiles start dropping off within a week, month, year?

I find it difficult to believe that the Unibond stuff I've used is utterly rubbish. I would have thought the difference between it and BAL was longevity.

There is a window of opportunity to pop all the tiles off and scrape the still stodgy adhesive off and redo properly, although this is quite a depressing thought as I've just put the new bath in. If I were to do this, would I be able to reuse the tiles even though there's a residue of the old adhesive?

(They are mostly glazed ceramic tiles with about 10 mosaics - all 200mm x 100mm)

 

[scubapete]

For your information...

I just rang the Unibond helpline and they said the adhesive dries by water evaporation and therefore can take some time if it's cold/humid etc.

The reason their instructions recommend a PVA coat is to prevent the water being sucked straight out of the adhesive which will make it difficult to apply to the wall.

If I use it to grout and make sure I pack grout into all the gaps, it should be left for a good few days (he suggested 4!) before using the shower.

He said as long as the tiles are fixed and solid and I fully fill the gaps with grout it will be waterproof and good for power showering. I shall be holding him to it.

Pretty incredible timescales.

For the remaining bathroom wall, I shall be following the sticky instructions to the letter...

 

[mountford]

It sounds like this bloke dosnt know what he is taliking about but hey I am only here to offer advice as I always tile to british standards.

You should ask him about PVA and show him how easy it is to peal of your hands once it has dried, remember you are now tiling to PVA not your original substrate.

Hope it all goes well.

 

[scubapete]

I had no intention of being rude, I'm just trying to fully explore my options.

Not worried about the PVA aspect as I didn't apply any. What I am worried about is water resistance. I was looking at the BAL website for a waterproof grout (i.e. barrier to water) and their product data sheets. They all say don't use the shower for two weeks after grouting. Is that for real?

I accept the A+ solution is to rip them all off, tank the walls and apply proper adhesive and grout. My biggest problem with that is my wife will probably rip my bo****ks off.

Is a B solution to apply a good specialist waterproof (i.e. barrier to water) grout and to be doubly-safe apply a liquid sealant to the grout?

 

[Spr0cket]

Be careful of your interpretation of the word water proof.

BAL for example don't use the word lighlty. It's water resistant in most cases, inferring it will not degrade if submerged in water. It will though still allow moisture to pass through - the amount varies by prodcut, but all the cement based adhesives or grouts will allow some porosity.

However to provide a true barrier to water you would need to either tank the surface prior to applying tiles, or ..... use a waterproof grout such as the epoxy based products from BAL.

Tanking whilst time consuming is likley a far easier DIY option for the type of use you describe.

Though to be honest, good grout, applied properly to a room which has adequete ventilation in daily use and does not get pounded by a power shower will most likely be water resistant enough.

Just my totally unqualified and personal view of things you understand...

 

[mountford]

As said in post before only 1 grout that is waterproof and that is epoxy you can only get it in white ivory and grey. That is the only way you can stop the water from getting through. It dosnt matter if you have tiled it right put enough groout in the joints and got enough ventilation water will still penetrate through e cementous grout.

The only other way you could make it waterproof is to use the aquamix products I have mentioned in posts before, they do a product called grout colourant this is a epoxy based liquid that you apply over a cement grout and it is as good as epoxy grout then. I found them at
www.trades-direct.co.uk these guys have there whole range.