The sanded mould usually get a very smooth and shine surface finish, I am wondering how does those matte surface coming from, sand after done? or sand the mould with small grit sand paper before laying? Thanks alot! Any information is welcomed.

You would get a matt finish from a matt mould, however the finish is not always even so very rarely does it look great.  Also many release agents will add a gloss finish to the surface thus ruining the matt effect even more.

The most reliable way, in our experience, is to use a matt or Satin lacquer sprayed onto the part after manufacture. The lacquers generally go down very evenly with a good even finish to them.  Also most lacquers are UV stable so you have the added benefit of further UV stability. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant