Why is a scratch coat recommended to be applied to the tile back during installation?
Why is it recommended?
For improved bonding between the tile and substrate.
A good adhesive contact and coverage will ensure better distribution of impact and stresses received by the tile finish, thereby reducing possible tile damage.
How is it done?
After applying a notched coat of the adhesive mix onto the substrate, use the flat side or notched side of the trowel and comb a thin layer of adhesive onto the back of the tile, then quickly lay the tile.
Ways to achieve improved bonding
(1)
Choosing a suitable notch-size trowel to apply the adhesive mix.
Selection criteria of the notch size include factors such as
(i) size of the tile / stone,
(ii) substrate accuracy and
(iii) area of final use.
(2)
Application of adhesive onto the substrate and the tile back with a notch trowel
(3)
Press in the tile to ensure that the adhesive layer is well compacted and rid of air voids. Excess adhesive to ooze out at the sides.