Disclaimer: This information is offered with NO liability or responsibility on the part of PITCA.
The following information is either from our personal experience, gleaned from various conversations and meetings, or from reliable Internet sources. It's emphasized that heating a trivet can remove existing enamel or loosen glitter. Also, vigorous cleaning techniques used on Cast Iron can scratch Brass. The preservation of patina is always a consideration when dealing with antique metalware. Be sure to read through the entire article first before proceeding.
Method #1: Cleaning, then seasoning the trivet
You’ll notice a slight odor while the trivet bakes; open a window during this process.
1: Wash the trivet well in warm soapy water. NOTE: If the trivet is plated or has traces of paint, enamel or glitter, STOP HERE.
2: Scrub until the trivet is free of rust, using *Bon Ami powder (see below) & a steel brush, steel wool or Brillo Pad.
3: Dry the trivet with paper towels.
4: Coat the trivet with vegetable oil and let sit for 15 minutes while you ...
5: Preheat the oven to 300 degrees F.
6: After 15 minutes, carefully wipe off all the oil with paper towels.
7: Bake the trivet on a rack in the oven for 1 hour.
8: Allow to cool on a baking rack.
* Note that Bon Ami is not interchangeable with Barkeeper's Friend. Bon Ami has no oxyalic acid or chlorine and is less abrasive than other cleansers.
Bar Keepers Friend has oxalic acid and is slightly abrasive. Oxalic acid dissolves rust and will take the color out of fabrics just like bleach. Barkeeper's Friend Cleaning will strip a cast iron pan of seasoning.
Method #2: Glorifying Antique Polish
The citrus and beeswax formula in this polish is designed for wood but it's also great for polishing and protecting the decorative cast iron you display. Just gently clean a trivet, apply polish, let sit for about 15 minutes, then wipe off and buff the to a beautiful shine. It's especially useful for cast iron trivets with enamel or japanning, finishes that could bake off if seasoned in a hot oven. Jim Ellwood (Trivets & Stands) recommends this polish and Lynn Rosack (The Expanded A-Z Guide To Collecting Trivets) also uses and loves it. WARNING: not to be used on cast iron used for cooking.
Wash the trivet well in warm soapy water. Clean until the trivet is free of dirt and grime, using a soft dental toothbrush, nylon brush or soft sponge. Dry the trivet with a cloth towel.
Following the directions on the product, polish with a brass polish. There are special considerations when working with brass:
Advice from the Henry Ford Research Center:
“Historic cast bronze is usually 90% copper, 6% tin and 4% zinc. It has been widely used since antiquity for weapons, sculpture and decorative objects. Bronzes are traditionally patinated and usually appear anywhere from light green to dark brown. Patinas are sometimes described as any controlled corrosion that imparts an aesthetically pleasing color and/or texture to the artifact. Patinas may be applied with chemicals or may have accumulated over time naturally; in either case, owners should be aware of the potential value of these finishes.
"Stable or painted surfaces should be kept dust free. Vacuum-clean all stable artifacts regularly, using the nozzle attachment with a brush. A bristle brush or a toothbrush may help to raise dust from crevices."