Covering element, method for decorating a covering element, and machine for decorating a covering element
A set comprising a plurality of covering elements for floors and/or walls, wherein each covering element comprises an upper surface having a pattern and at least one distressed upper edge, wherein at least two covering elements of the set comprises substantially the same pattern, and wherein the shape of the distressed upper edge differs in each covering element of the set.
1 . A method for decorating covering elements for floors and/or walls, comprising the steps of:
providing a backing of green ceramic material for the covering element;
distressing all upper edges of the green ceramic material backing;
applying at least one coating layer on an upper surface of the green ceramic material backing after the distressing step, the at least one coating layer comprising a glaze; and
firing the covering element comprising the green ceramic material backing and the at least one coating layer in the same step after the distressing step,
wherein the distressing step is performed by a shaped grinding wheel that rotates about its own axis at a variable rotation speed such that each distressed upper edge has a different shape from other distressed upper edges,
wherein the green ceramic material backing is conveyed along an advance direction by a conveyor,
wherein during the distressing step, the green ceramic material backing is retained by retaining elements in a substantially fixed position relative to the conveyor, the retaining elements comprising a horizontal border that presses on a central portion of the upper surface of the green ceramic material backing,
wherein the horizontal border comprises a band or belt driven along the advance direction, and
wherein a width of the horizontal border is less than a width of the green ceramic material backing.
2 . The method according to claim 1 , wherein the at least one coating layer is applied on all of the distressed upper edges.
3 . The method according to claim 1 further comprising a step of applying a pattern on an upper surface of the green ceramic material backing after the distressing step.
4 . The method according to claim 3 , wherein the step of applying the pattern includes the application of the pattern on all of the distressed upper edges.
5 . The method according to claim 1 , wherein the at least one coating layer comprises a glaze.
6 . The method according to claim 1 , wherein the shaped grinding wheel is not flat.
7 . The method according to claim 6 , wherein the shaped grinding wheel has protuberances and/or pits.
8 . The method according to claim 1 , wherein the variable rotation speed is between 15 Hz and 70 Hz.
9 . The method according to claim 8 , wherein the variable rotation speed is between 20 Hz and 60 Hz.
10 . The method according to claim 1 , wherein the step of providing the green ceramic material backing comprises compacting powders of ceramic raw materials by discontinuous pressing to form a compacted green ceramic material backing, and drying the compacted green ceramic material backing.
11 . The method according to claim 10 , wherein the distressing step is performed after the drying step.
12 . The method according to claim 10 , wherein during the compacting step, a relief is formed on a central portion of the upper surface of the green ceramic material backing.