There are different types of materials that are usually used for feature wall tiling. Natural stones: Is probably the most common used feature wall finish and also the most temperamental. Stones are not like other tiles, they come in different grades depending on the quarry and at most times are moisture sensitive. So knowing your stone and adhesives compatibility is crucial to ensure warranty on your work.
With all stones the application method is always the same, back butter and trowel to ensure full coverage (No exceptions).
That is why there cannot be imperfection in the tiling, as it will really stand out. Since there is no give with tiling mosaics due to the small size tiles and the 3mm notched trowel application method then it is crucial for the preparation of the wall to be completely plump. It is highly recommended to render walls on brick and properly sheet timber-framed walls including setting.