The name “Sweet Iron” originally comes from the Spanish and is used in the manufacture of the mouthpieces of Bomber’s Bits. This involves techniques that are practiced by very few bit makers today.
The benefits of “Sweet Iron” are many. First of all “Sweet Iron” feels warm to the touch when compared to stainless steel. This will aid in the initial acceptance of the bit with the mouthpiece feeling warmer than stainless steel. Then there is the oxidizing, which produces the slight fizzing sensation experienced by the horse, which encourages acceptance and salivation. It is this sensation that sets it apart from inert stainless steel. Copper on the other hand produces a much more intense sensation that can lead a horse to becoming immune to the over stimulation.
Note that the blue finish of Bomber’s Handmade Bits is not a coating but a side effect of the manufacturing process. The blue finish will eventually oxidise to anything between a nutmeg colour and a chocolate brown.