Baked on Oil Finish

Cast Iron Boof Sun 12x12 grate

Baked on Oil Finish

Nothing beats cast iron for permanence, raw strength and beauty. However, not everyone likes the initial orange rusting period and waiting one to two years for the natural patina to develop. Trench Drain System’s Baked on Oil Finish (BoOF) is a pre-rusting process that seals in a natural chocolate brown weathered appearance that bypasses the initial rusting stages.

When exposed to the elements, raw cast iron will quickly (sometimes within hours) turn from silver to an orange-brown as the exterior weathering oxidation begins. Over time, a stable oxide exterior patina forms that result in the dark brown appearance we are accustomed to seeing on old cast iron commonly seen in streets and parking lots. The complete natural process does require time and the unsightly rust runoff can potentially stain nearby surface areas.

There are many factors that determine how long it will take for the color to change to a rustic brown patina. One factor is regional conditions in which inland areas don’t see the harsh salt water that is experienced in coastal areas. Other climate conditions such as rain and snowfall amounts also play a role in how quickly oxidation occurs.

Shown is an Interaken grate when received raw (natural) from the foundry, after exposure to moisture and after the Baked on Oil Finish is completed.

Typical Applications:

  • Pool and Deck
  • Sidewalks
  • Courtyards
  • Playgrounds
  • Plazas
  • Memorial
  • Resorts


  • Variations Occur
    A variety of factors effect the color of the end product. Grates may vary in colors ranging from a chocolate-like brown to a dark, nearly black finish.
  • Baking Time
    The BoOF process is a lengthy and extensive procedure. Stock grates with BoOF may vary based upon pattern and size, we recommend calling for availability to allow for processing.
  • Benefits of BoOF
    Grates with a Baked on Oil Finish are pre-aged to provide a look that skips the bright orange phase of rusting that can be unsightly in some cases.


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