Method to manufacture a composite product with micro contoured surface layer

A method to enhance a surface roughness of a composite product, the composite product comprising:

• matrix material and organic natural fiber based material,
• the matrix material comprising a thermoplastic polymer,
• the composite product comprising micro contours on the surface having a depth of less than 10 μm, and
• the composite product having a surface layer capable to comprise at least 10 non-overlapping surface portions having a circular shape with a radius of 2 mm, wherein the micro contoured surface layer has an averaged colour variance (DE1) according to CIELab colour chart values in the range of 0.3 to 5 in a stained state or in the range of 0.2 to 5 in an unstained state, said stained state referring to a K&N or NP stained surface layer, when measured as a averaged colour variance (DE1) according to CIELab colour chart values from the at least 10 non-overlaping surface portions, the method comprising:
• providing the composite product comprising matrix material and organic natural fiber based material having a primary surface layer with a primary surface roughness level, a primary gloss value and a primary friction coefficient
• softening said primary surface layer of said composite product material by heating and,
• providing a secondary surface layer of said composite product material surface layer of said composite product material surface with a secondary surface roughness level, a secondary gloss value and a secondary friction coefficient by cooling said softened surface layer, wherein the secondary surface roughness level is different from the primary surface roughness level and/or a secondary gloss value is different from the primary gloss value and/or a secondary kinetic friction coefficient value is different from the primary kinetic friction coefficient value.