A particle mediated anodising process for white anodised surfaces

An aluminium anodising process to produce a white or substantially white anodised surface on an aluminium substrate, the process comprising the steps of:

• i. Pre-treating an aluminium substrate;
• ii. Immersing the aluminium substrate in an aqueous anodising bath comprising:
• a buffer,
• one or more particle sources,
• and one or more carboxylic acids;
• and
• iii. anodising the aluminium substrate by following an anodising current and voltage regime to provide an anodised substrate comprising the white or substantially white anodised surface.

An anodised surface configured on an aluminium substrate, the anodised surface comprising:

• i. an outermost substantially branched random nano porous layer having nanocrystalline walls located at an outermost position from the substrate;
• ii. a substantially nanocrystalline filled nanotubular middle layer;
• iii. a nanocrystalline bottom later in substantially in contact with the substrate and having greater density than the outermost and middle layer;
• wherein the substantially nanocrystalline filled nanotubular layer is positioned between and substantially in contact with the substantially branched random nano porous layer having nanocrystalline walls and the nanocrystalline bottom layer having greater density than the outermost and middle layer.