Surface Finishing

Surface finishing refers to different processes used to change a product how it looks and feels like. Different techniques are used to improve the appearance, adherence, solderability, resistance to corrosion, hardness, conductivity and many other characteristics of industrial components.

Our Surface Finishing Capabilities

PProto Expedited offers professional and high quality surface finishing service for our customers. We have more than 10 experienced experts who only do surface finishing job, therefore, you don’t need to worry the quality.

Choose The Right Finish For Your Material

Different surface finishes can be applied to different materials. You can easily find what you need for your material in the below sheet.


Name Material Compatibility
Smooth surface (1.6 Ra μm/64 Ra μin) All plastics and metals
Bead blasting All metals
Powder coating All metals
Anodizing clear (type II) Aluminum alloys
Anodizing color (type II) Aluminum alloys
Anodizing hardcoat (type III) Aluminum alloys
Brushing + Electropolishing (0.8 Ra μm/32 Ra μin) All metals
Black oxide Stainless steel
Chromate conversion coating Aluminum
Brushing All metals

What you can get from us

Here is a list of standard surface finishes. Please contact if the surface finish you need is not one of the below.

As machined

“As machined” is our standard finish for all metal and plastic parts. It has a surface roughness of 3.2 μm (126 μin). All sharp edges are removed and parts are deburred. Machine marks are visible on the surface.

Smooth surface

This can reduce part’s surface roughness and look smoothly. The standard smoothing surface roughness (Ra) is 1.6 μm (64 μin). Machine marks are less evident but still visible on the surface.

Bead blasting

Bead blasting is the operation of propelling, typically with compressed air, a stream of abrasive material (blast media) against a surface to affect the surface finish. Our standard grit is #120 unless otherwise specified.


Requirement Specification
Grit #120
Color Raw material color

Anodizing color or clear (type II)

Type II anodizing is a process done by placing the aluminum in a sulfuric bath which builds up the aluminum oxide on the surface as well as into the aluminum material too, about half and half. The fact that this process builds into the aluminum material also creates an interesting property of the aluminum oxide making it a great electrical insulator.


Requirement Specification
Thickness 8 – 12 μm (clear), 4 – 8 μm (color)
Color Black, clear or any RAL code or Pantone number

Anodizing hardcoat (type III)

Type III (hardcoat) anodizing is an anodizing process that forms an extremely hard, abrasion resistant, porous oxide on aluminum.


Requirement Specification
Thickness 50 – 125 μm
Color Black or clear

Powder Coating

The powder coated part is then placed into an oven to cure. The polymer resin within the powder begins to adhere with heat on the surface of the part, resulting in a thick coating that is incredibly durable compared to other surface finishes.



Requirement Specification
Thickness 18 – 72μm
Color Black or any RAL code or Pantone number.


Electropolishing is an electrochemical finishing process that removes a thin layer of material from a metal part, typically stainless steel or similar alloys. The process leaves a shiny, smooth, ultra-clean surface finish. 


Requirement Specification
Color Natural metal color.

Black Oxide

Black oxide is the conversion coating formed by a chemical reaction with the iron in metal to form an integral protective surface…contrasted to an applied coating which bonds to the metal but does not react chemically.


Requirement Specification
Color Black

Chromate conversion coating (Alodine/Chemfilm)

Chromate conversion coating for aluminum and other types of metal is a chemical immersion process that is used to passivate and convert the surface properties of the substrate.

Requirement Specification
Color Clear


Brushing is a surface treatment process in which abrasive belts are used to draw traces on the surface of a material. 


Requirement Specification
Surface roughness 0.8 – 1.5 μm
Grit #80-120

Let’s Quote Your Project!

Please contact us if you need other specific finishing.