Shadowing on moleanos limestone

[Alberti]

Hello fellow tilers

im new to the forum and have joined because I have a little problem.

i would prefere for the time being not to mention any particular source/companies.

after using a standard set white adhesive on 600X400 moleanos limestone a shadow affect where the adhesive was making contact to the back of the tile appeared. At first I thought as it was standard set there was still moisture on the face of the tile. The customer was then on holiday for three weeks and on the return they informed me that the tiles hadn't dried. Since I have damp metre tested it and it's drier than our turkey will be this Xmas.

I have have contacted the adhesive manufacturer and a well known chemical manufacturer and they have both come up with different conclusions. One says the polymers in the adhesive have come through to the face of the tile due to using a standard set. The other says it has nothing to do with the adhesive and is because the limestone has traces of iron pyrite which have come through to the face of the tile....guess which one blamed the tile?

just wanted to know if anybody else has seen anything like this and which of the two explanations seem more realistic.

thank you

 

[beanz]

Did you back-skim the tiles?

 

[Alberti]

Did you back-skim the tiles?

I did. Some are completely discoloured. Some are random. Some are even perfect.

 

[Concrete guy]

It's the polymers in the slow set causing the problem.

There was an identical situation discussed on another forum only a month ago. I'll find the solution and post it up.

 

[Concrete guy]

Johnny - (who also posts on here) came up with the following explanation and solution for a similar problem:-

ok im going to make some observations and this is only from me , not a qualified tiler .
i hope that the latter part of my post will sort out the current thread problem.
i am self taught but have made this profession my life career choice for last 28 years.
so i will take no offence if you shoot me down .
this thread has thrown up a stone face stain problem that i have been seeing for more than 20 years .
the reason i am going to make this statement is that i hope i can help others understand how to avoid problems in future.
I will try to keep this as short as possible.
twenty plus years ago everyone i knew was using x7 white(not fast set ) and ardion 90 or similar when fixing limestone over underfloorheating .
we soon found out that even though we solid bedded the tiles, especially moleanos the stone remained mottled or dark long after we had fixed it.
you could wait six months and the stone would not change colour .
this did not make sense .
i did a lot of tests and soon realised that the stone may look wet but it could well be dry!!
what i believed was happening was that the polymers in the adhesive were migrating through the stone and bringing through mineral content of stone that might otherwise be unaffected by rapid set adhesive.
the face of stone had a furry texture that could be easily removed with wexa or similar.(provided the adhseive has had time to dy out )
at this point in time no one really knew what we were meant to do.
obvious would be S16 and ardion 90 .but what did we know about rapid sets in those days with limestone so they they would not let the moisture leech in to stone face!
I have seen this umpteen times before and been able to remove with a simple wexa scrub and if it is on a wall .
all may not be lost.
I have saved walls and floors like this many times .



sorry i missed an important point.
twenty odd years ago i was obsesssed with the problem of staining of limestone .
my problems were a fraction of the example in the thread .
but still if i had a 10% void under a tile it would be shown when using a non rapid adhesive.
I actually did not know at this stage that i really needed a fast set that would dry by hydration and pull the moisuture within itself.
i will always remember a eureka moment when i met (jason of universeal ) who was then a rep for weber and we met up on site to discuss the new stoneset weber range.
he gave me some samples and quite bizarrely i found that weber had formulated a non fast set flex adhesive that did not stain sensitive stone faces .
they had no idea that they had this great fromula for stone till then i think .




as a test to see if it works mix wexa with water 1:6 . apply with sponge to half an affected tile
try not to let the cleaner run down tiles( difficult)
keep stone wet for 5 mins and dont let it dry in. agitate and scrub with a green nylon scour pad(dont scratch stone) or white pad for a minute.
wash off with water and dry off with a hairdryer.
may need to do it a few times if it is a very porous moleanos.
the longer you leave stone to dry out the harder to clean stains off.
if you touch the affected areas that are blotchy they will probably feel a bit furry whereas unaffected lighter stone will feel smooth.
this type of marks are no different to picture framing when grouting limestone .
it always happens on jobs we do where the stone is very porous and we have had to use a water based sealer because did not have time for stone to be bone dry before kitchen went in.
the moisture from grout eeks in to side of stone.
you should leave for a couple of days to dry before wexa clean down joints.
we usuallly leave two weeks whilst kitchen goes in and then clean and final seal with mn stainstop or similar.
the onlyy time i have come across problems are when stone is left over a month before cleaning.
let me know how you get on

 

[Lee@emctiles]

You beat me to it Alan @ATS !

Yes, tiler has simular problem a month or so, used the Wexa and job has now been rectified.

(do a text patch first.)

 

[jonnyc]

Lee haven't seen the photos of the other problem after cleaning.can you get the toiler to post them up sometime

 

[White Room]

Lee haven't seen the photos of the other problem after cleaning.can you get the toiler to post them up sometime

I thought you was from Surrey not Ireland :lol:

 

[jonnyc]

Are we not toiling all our lives .
sorry need to use spellcheck

 

[Lee@emctiles]

Lee haven't seen the photos of the other problem after cleaning.

I have requested pics but tiler hasnt got any Jonnyc

product he used was LTP Power Stripper (Not Wexa as originally stated.)