The Choice of Material for the Bird Cages
The first bird cages I made were of "mild" steel, not stainless, as this was an economical way to learn the craft. Over time, as the quality and intricacy increased, I began to search for superior steels to use. Fighting corrosion should not be an active part of owning artwork, if at all possible.
Galvanized steel was quickly determined to be unusable, as continued contact is toxic to both humans and animals, and is a wholly unattractive material. Likewise, powdercoated bird cages are also toxic, in time, as the powdercoat begins to chip off in small bits, revealing areas for corrosion to enter. Plating occurred to me as an option - as copper, brass, or gold plated wirework is very beautiful to look at. But again, for durability and longevity plating is questionable, especially with the possibility that these cages could house a living being. Even the best plating jobs are subject to the abilities of determined beaks and nails!
I was after a material that could be itself, that did not need to be cloaked with a thin layer of improvement; I wanted something that could really shine on its own terms: Stainless Steel!
Stainless Steel - Which Kind?
150 varieties or "grades" of stainless steel are available now, and about 15 are in common use. Grade 302 (used to clad the pinnacle of the Chrysler Building) and grade 304 (used to make many countertops, appliances, and other stainless bird cages) have long been the workhorses for many products, and they are fine choices. However in recent years another grade has become more available - grade 316. It is still considerably more expensive than 302 and 304, but its deep reflectivity and greater anti-corrosive properties have influenced leading designers' preferences. For example, the Patronas Twin Towers and the Jin Mao Tower both use 316 on their exterior.
Determined to use the very best stainless available for this application, considerable research and testing went into the decision to use grade 316L (The "L" stands for low carbon, explained below). This is the same grade of stainless steel that jewelers and watchmakers use owing to its luster, permanence, and compatibility with biological organisms: piercings are made of 316L, and also medical implants such as pins, screws, and orthopaedic implants like total hip and knee replacements. Pharmaceutical companies use this grade in their processing equipment. If it really matters that an item remains perfect, 316L is chosen.
The Science of Stainless Steel
Below is a Metallurgical Test Report (MTR). An MTR is issued with each batch of stainless steel that a mill produces, and relates the composition and tolerances of that batch. Following the MTR, several details of interest are highlighted and explained. Please scroll down to view these notes regarding the stainless steel that the bird cages are constructed of.
MO Molybdenum "Moly" is added for further corrosion resistance over grade 304.
MN Manganese (added in greater quantity over 304) adds to the tensile strength, and makes the chemical bond of the stainless more stable.
NI Nickel (added in greater quantity over 304) gives the same advantages as Manganese, but also helps to impart a smooth and polished finish.
CR Chromium must be over 10% to qualify as a stainless steel, and over 16% to qualify as grade 316.
L stands for "Low Carbon", which helps the stainless to be immune to sensitization, which is a form of corrosion that occurs after welding. A carbon "C" content of less than .3% is enough to prevent this problem.
RA denotes the average surface roughness. The lower RA numbers associated with polished stainless steel mean there are less places for bacteria to hide. This "more average" surface also reflects more light.
CM Country of Melt: US means that this stainless was produced in the United States. There are many reasons why this is important. Please see the page Responsibility to learn more. (Coming Soon)