Recently, some customers have been inquiring about “baked oil finish”. This finish is produced by coating iron castings with used vegetable oil and then burning it off in a powder coating oven.

Oxidizing (burning) vegetable oil in the presence of iron at a temperature typically well above 300° F but below its flash point will result in a greasy golden brown residue which is a long chain organic molecule (organic polymer ). Anyone who has inadvertently left cooking oil too long in a hot frying pan will be familiar with this residue as it is exactly the same thing. Cooks have been “seasoning” their cast iron cookware this way for centuries creating a sort of do it yourself Teflon.

The purpose of this finish, ostensibly, is to create a surface that mimics an aged patina finish. This finish, which wears off over time, is promoted as a way to avoid the “orange rust” phase of the natural patina process.

At IRONSMITH, we feel there are some factors that should be taken into account before specifying this finish.

1. Baked oil is not a “Green” finish.

  • The finish requires energy to apply in the baking process. (More than a typical powder coat application. Temperatures in excess of 200°C (392°F) for as much as an hour may be required for complete cross linking. Temperatures below 140° C will result in minimal cross linking or polymerization) The energy for the ovens is typically natural gas.
  • The burn off of the oil produces pollutants of several kinds including green house gasses (CO2, CO,) and PM10 class particulates (10 micron particulates known to cause health problems and restricted by the EPA South Coast Air Quality Management Board etc.). One can see this for one’s self in the smoke from an over heated fry pan of oil.
  • Excessive vaporized by-products of heating used cooking oil require frequent changes of oven exhaust filter systems introducing more product into the waste stream which are possibly contaminated with known carcinogenic by-products contained in waste cooking oil.
  • Application of the oil before baking creates more contaminated waste products ( rags , protective clothing etc.)
  • Transportation of used oil creates additional environmental hazard spill risks.
  • Exposes workers unnecessarily to a known carcinogen, waste cooking oil.

2. Baked oil has no track record in the field

  • To date we know of no extended exterior field trial of this type of finish.
  • There is no standard for the application of baked oil finish in any industry. Nor is it used commercially in any other industry or any other product.
  • There are other safer proven options to accomplish the same result.
  • Cannot be touched up in the field.
  • No track record of rust protection

3. The end result is the same.
Over time both an unfinished grate and a “baked oil finish” grate will look the same. We feel this process, then, has no real benefit but has real economic and environmental costs.

4. Other options exist
For those who do not wish to wait for the natural patina process or are concerned about rust bleed into other surfaces we recommend our Rust Powder Coat or a Black Max rust conversion.

Natural aged unfinished iron grate

IRONSMITH has supplied baked oil finish on several projects. We have done extensive testing to try to improve repeatability and reduce environmental impact and we have come to the conclusion that BAKED OIL FINISH IS AN ENVIRONMENTALLY UNSOUND PRACTICE. We are very much in favor of recycling of all kinds and the safe and efficient recycling of waste cooking oil is environmentally important. There are many commercial uses for properly processed WCO from biofuel to soap and cosmetics. We don’t believe that a decorative finish for iron grates is a proper use of this resource.