Honed limestone weathered banding problem

[philbur]

Hi, I'm new here, of course I've pitched up because I have a problem, see the attached photo. The tiles are random length Limestone Jura Mix. The banding appears to be due to the ends of the longer tiles (stacked vertically) being exposed to the elements during storage. The tiles are now laid and sealed and I have a large number with the banding issue. Any suggestions on fixing the problem would be most appreciated.

Best Regards
Phil

 

[Qwerty]

Do you know if they were washed down thoroughly prior to sealing?

 

[philbur]

Hi Geoff,

I don't know but I suspect not as the surface was very grubby after sealing, but that's another story!

Regards
Phil

 

[Qwerty]

I would be looking to strip back the sealer, cleaning the tiles thoroughly afterwards to see if it is grime or if something has etched the stone.

 

[philbur]

Hi Geoff, thanks for the input. The two current theories are: some kind of etching due to being exposed to the elements resulting in a difference in the absorption of the sealant or, the ends were dry and the centre surfaces in contact tile to tile were still damp after laying and due to the porosity the sealant wasn't absorbed uniformly.

This raises an interesting question. No matter how aggressively I remove the top surface of sealant I am unable to change the underlying colour. Which would seem to make sense as the pores in the tiles are filled with dry sealant? However the general recommendation is to reseal in high traffic areas once every six months or so, in order to avoid accidental staining. These two situations seem to be contradictory?

Regards
Phil

 

[jonnyc]

phil

i have seen this numerous times when stone stacked in crates like this.
it is particularly common with jura and bateig.
it is to do with that part stone being exposed to sunlight i believe.
I have tried many cleaners on stone even before fixing with not much luck.
jura changes colour over time after stone has been fixed through oxidation but it usually goes darker not lighter.
i have recently seen a jura grey floor i did 18 months ago and it had changed from grey to brown.
this was not because it was dirty just oxidating.
your problem seems to be the reverse with the exposed pieces being lighter.
could this be because you have sealed the floor before the stone had time to dry out properly .
the exposed bits had maybe alot of time exposed to sun and bone dry and rest of tile was damp from cutting and packing .
jura can take quite a number of days to dry.
if this is the case the darker part of stone should dry even through the stainstop .
but what you might find is that what you thought was the lighter part of stone on exposed edges becomes the darker because this part has been affected by being exposed to light.
you wont know this until the stone has thorughly dried.
it can be very confusing especially if the stone had been stacked outside for a while uncovered .those exposed parts have dried but then it could rain again before delivery and when you receive it all looks the same ie wet.
when floor starts drying out after laying you start to see what you have now ie lighter edges

 

[jonnyc]

if you want to find out quicker what real problem is , you could buy a litre of lithofin asr.
i use it if i have restoration job and too much stainstop applied and streaked on stone.
it should help release some of the stainstop .
clean half the dark part and half the light part on an inconspicuous tile with this problem.
then dry tile out with a hair dryer but dont be too hot and burn the face of tile.
dont leave the asr on too long .
when you have dried out the tile this may reveal whether the middle of stone was still damp when sealed and now lightened up or may also reveal that the edges now look darker than the middle.
call casdron and ask for bob who i know and maybe send him a photo and see what he thinks.
i know of a stone floor recently that a stone supplier paid to be ground back and rehoned to get rid of this problem. it is a common problem that a supplier while not repeat a second time round if they are deemed responsible
by all means give me a call if you want to discuss

 

[Concrete guy]

As jonny says, this is UV light exposure (with possible acid etching from acid rain).

Jura is very dense as far as limestone goes, it's almost a marble and is often referred to as Jura Marble.

Are there any spare tiles left from this batch with banding? If there are then I'd suggested grinding and re honing the surface to see how it responds. I can't see you getting any joy with chemicals to be honest.

This looks likes a grind and finish job to me.

Take it up with the supplier of the stone also.

EDIT - Just noticed Jonny has already suggested this - I'd only read his first response.

 

[jonnyc]

As jonny says, this is UV light exposure (with possible acid etching from acid rain).

Jura is very dense as far as limestone goes, it's almost a marble and is often referred to as Jura Marble.

Are there any spare tiles left from this batch with banding? If there are then I'd suggested grinding and re honing the surface to see how it responds. I can't see you getting any joy with chemicals to be honest.

This looks likes a grind and finish job to me.

Take it up with the supplier of the stone also.

EDIT - Just noticed Jonny has already suggested this - I'd only read his first response.

what do you think of fact that the edges are lighter than middle of stone ?
it should the other way round .
do you think the unexposed edges in middle could still be damp.
i cant think of any other possibility.
the only other time i have seen this was on the jura job i mentioned i did 18 months ago.
i had a very serious problem with jura grey polished sweating under floor covering which builde put down. it got zebra stripes all over it and could not get off. marble shine ground and reploished whole ground floor to cure that problem.
but on the landings and stair cases which i did not do because i did not want to supply because of potential problems in this original post, some areas were covered and some not for many months.
when the final clean was made and all covers taken off the areas of stone up to say 6 inches off the skitings were lighter than the area that had benn covered and was still that way 18 months later.this is the opposite of what you would expect .
can you shed any lihght on this?

 

[Concrete guy]

I think the OP's issue is UV exposure which has "Bleached" the surface, in much the same way you used to get these markings with Saltillo terracotta. This would have occurred at the quarry when the tiles were cut and stacked. But it's more than just UV, it's probably a chemical process such as acid rain that combined with UV exposure has created the lighter areas.

Another alternative is moisture content, covered areas in the one you discuss above and the OP's has created a reaction when the sealant was applied, the drier areas of stone have soaked up more sealant.

If a re grind solves either of these issues then it can only be 1mm or so deep into the surface.

We would occasionally get issues of this nature with granite slab, in most cases it was a dye or other chemical reacting with UV light.