Damp/Wet Patches On Wall Tiles - Tile Advice

[Prateek]

Hi !
After laying of the wall tiles of the size 13" x 10" (Joint-Free) patches have started to appear on them and don't seem to be drying up. Is there a problem with the tiles or in the method of laying of the tiles ?
Could you please suggest a solution for the drying the patches along with the precaution we need to take before laying these tiles, to prevent such patches ?
Do let me know if you require any further information.

 

[White Room]

What was the substrate, what adhesive was used, was the substrate dry before tiling....and why did you not have any joints.

 

[Just Rizzle]

what are the tiles made from?
did u back butter the tiles?

 

[Tile seller]

All I can see is dry/damp grout on the tiles.
Does it look ok when the grout is sponged off?

 

[Dougs Third Go]

weird...my guess is a dispersion adhesive has been used and it's showing through towards the centre of the sheets where it hasn't set, no joints seems a bit strange too.

 

[Spare Tool]

Are they mosaic sheets or tiles with a mosaic print, look like the latter to me, if so could be the combination of lack of joint and bucket addy...no where for the moisture to go but into the biscuit, strange how its only in patches though