The X-Tiles Video Series: CNC Machined Metal Finishes

Watch part 4 of our video series, the X-Tiles, to help you distinguish between Xometry's 25+ CNC machining metal finishes—including common finishes, "clear" finishes, and conductive finishes—and choose the best finish for your project.

By Greg Paulsen · October 22, 2019

Xometry offers over 25 finish options for parts machined through its network in the Xometry Instant Quoting EngineSM. These finishes and more are also offered through Xometry Finishing Services for parts that have already been machined through other suppliers. Our latest X-tiles video series answers various questions our customers often ask about CNC Machined Metal Finishes.


Lightning Round: Common Metal Finishes

The first video on our list briefly highlights different surface finishes for aluminum CNC machined parts. In this case, a 1.5” X-tile was machined out of 6061-T6 aluminum. While the standard finish is left as-machined, we compare other tiles which show chromate conversion (chem film), anodizing (Type II and Type III), and nickel plating.

Take the next 4 minutes to see several common finishes from chem film to anodize to metal plating.

Managing Expectations for “Clear” Metal Finishes

A very common misconception when choosing additional metal finishes is that the base surface is unaffected by treatments like clear chem film or clear anodize. To the contrary, there are noticeable visual differences as well as an increased surface roughness after these finishes are applied. Check out the video below to see the results of clear metal finishes.

What does milled aluminum look like after applying a clear finish such as chem film or anodize? This 3-minute video will show you.

Bonus: Yellow and Clear Chromate Conversion

Xometry typically applies a chromate conversion per MIL-DTL-5541. Clear chromate (chem film) can also be specified to RoHS (Restriction of Hazardous Substances). Gold chem film is also described as yellow or Iridite and is a very popular surface preparation treatment. Not only do these methods prevent corrosion, but also they are excellent as a foundation for secondary treatments like anodize (with masking) and powder coat finishes.

Check out the differences between clear and yellow chromate conversion coatings in this video.


Metal Plating and Chem Film, Keeping Conductive Surfaces

There are two primary ways of treating a metal surface for corrosion resistance while maintaining a conductive surface: metal plating and chem conversion coating. The video below shows the differences in the finishing processes as well as why one may be chosen over the other.

Conductivity is important for PCB ground planes, surface prep for additional finishes, and electrical connections..

About the X-Tiles

The X-Tile series takes a show and tell approach to manufacturing outcomes using various platforms, materials, technologies, and finishes. You can check out the other posts in the series here:

What is an X-Tile? We took the ‘X’ from our Xometry logo and designed a custom part that is about 1.5 inches square. It has flats as well as angled surfaces. The tile is producible in multiple manufacturing processes and acts as a good comparison part for material finishes and cosmetic features like layers.

Xometry’s X-Tile

Xometry's X-Tile

If you have a suggestion for an X-Tile spotlight or comparison, let us know! Subscribe to Xometry’s YouTube page to get the latest video content as it comes out!


Xometry offers a variety of common and custom metal finishes on parts machined through the Xometry Instant Quoting EngineSM. For parts that are manufactured elsewhere, Xometry Finishing Services offers these finishes too.

The image to the right shows the instantly-quoted finish options for CNC machined aluminum, like 6061-T6 or 7075-T6. Xometry’s auto-quoted, turnkey finishes include:

  • Standard (As-Machined)
  • Bead Blast
  • Anodize
    • Type II Black
    • Type II Blue
    • Type II Clear
    • Type II Gold
    • Type II Green
      Type II Orange
    • Type II Purple
    • Type II Red
    • Type II Yellow
    • Type III Black Hardcoat
    • Type III Clear Hardcoat
    • Type III Gray Hardcoat
  • Chem-film
    • Clear Chromate Conversion
    • Gold Chromate Conversion (Iridite)
  • Metal Plating
    • Electroless Nickel Plating
    • Gold Plating
    • Silver Plating
  • Electropolish
  • Passivation
  • Powder Coating
  • Heat Treatments
    • Annealing
    • Temper
    • Through Harden
  • Custom Finishes and Combinations
21 finishes offered in the online quoting platform dropdown menu

Posted in Machining Manufacturability Tips Videos