Determine How Old That Knife Is

Determine How Old That Knife Is!

By Bill Rudich

This article was written for a knife publication but the same principle can be used for firearms as well. ~ You should certainly be able to tell an 1890’s era Colt Single Action from a Second Generation.

Recently I had the opportunity to visit a metals analysis laboratory. While there I saw dozens of tests performed on some new stainless steel alloys. Testing is often performed on a metal sample to determine its properties, strength, and malleability and corrosion resistance. Even polish or the ability to be polished can be determined.

In the instance that brought me to the lab the alloy needed to be determined. It seems that some Chinese stainless is, as an example, marked T-34 but its magnetic properties are not the same as the American made alloy.

While we were waiting to get test results, which take only minutes, we discussed just how much can be determined about a sample. The people at this particular lab had recently tested an Indian ax for a customer prior to him paying big bucks for a potential fake.

“The Optical Spectrometer can date a metal sample to within 10 years of manufacture.”

They now have a pretty common Optical Spectrometer which can test metals nondestructively. The instrument needs a 1/8 inch diameter test spot. This can be in a hidden area on the item or sample. I was told the cost of the test runs about $45 to $60 dollars and it could save you a lot of trouble and money for something that wasn’t right. 

If the lab has a reference library, they can look back at alloy make-ups and determine when the item being tested was made. It seems alloys have changed over the years and although the Optical Spectrometer dating method cannot give you a specific year, it can date a metal sample to within 10 years of manufacture and often determine country of origin as well. The lab you use needs to have a good technical archive to determine the match of alloys to date. This dating is not to a specific year, but to within 10 years of manufacture.

A ten year span is close enough for our needs and will certainly be able to determine if it was made in 1860 or 1960. Or confirm if that the stiletto you are hoping to add to your collection is really from around 1958 or a later production 2000 model!

I should also mention that this equipment can test all metals including precious metals, copper, bronze, brass and the alloys of all these metals.

Working principle of a stationary metal analyzer

The principle of the analysis method of SPECTRO´s stationary metal analyzers is optical emission spectroscopy. Sample material is vaporized on the spark stand by an arc or spark discharge. The atoms and ions contained in the atomic vapor are excited into emission of radiation. The radiation emitted is passed to the spectrometer optics via an optical fiber, where it is dispersed into its spectral components. From the range of wavelengths emitted by each element, the most suitable line for the application is measured by means of a photomultiplier.

The radiation intensity, which is proportional to the concentration of the element in the sample, is recalculated internally from a stored set of calibration curves and can be shown directly as percent concentration.

Bill Rudich is a member of the Arizona Arms Association and the Editor of the Automatic Knife Association publication, AKA Switchblades. 

From the Arizona Arms Association Newsletter - February 2005