PVD and Alloy: Two Terms You Should Know Before Buying an Asian Wristwatch

Most of us speak at least two languages, we just don't realize it. For example. a medical doctor speaks English and then he or she speaks Medicine. The later is a subset of English, which only medical professionals speak. For example, a doctor might say, "you make my heart have premature ventricular contractions".  In simple English, that means you make my heart skip a beat. (From a film).

Now, imagine watch speak. Here's a tidbit: "the cannon pinion needs a ping to tighten it up. I could use a closing punch and stump". In regular English you might say, "I'm going to tighten the hour hand on your watch".

Here's one more and then we can move on to the next subject. "I have a headache, what do you recommend?" The pharmacist replies, "a Non-Steroidal Anti Inflammation drug". What? "An aspirin".

So you want to buy a watch and the listing mentions PVD

PVD stands for physical vapor deposition and describes the most current way to put gold over stainless steel. It allows someone to "coat" or deposit gold on stainless steel by vaporizing gold in a heated vacuum. Before PVD existed, we had to bind metals to put gold on a surface.

The best example of  binding gold with the surface of steel is electroplating. That process involved the use of electricity to mix molecules of gold and with a steel surface. With electricity molecules of gold became part of and weakened the surface. Yes, it weakened the surface.

Since 2007, gold has gone from a metal used for adornment (jewelry and watches) purposes to a medium of exchange. It's a commodity and used for investment purposes. It's too expensive to use in the making of watches.

PVD Bezel

Today, people use stainless steel to make watch cases. Precious metals are unaffordable and impracticable to use in making watches. But, many people still want gold watches. That begs the question of how to provide an inexpensive way of plating a watch with gold.

In 2010, NASA scientists at the Glenn Research Center in Ohio perfected the PVD process - a relatively recent development. If you're seeing watches and wonder if they're really gold, then you're probably seeing a gold film deposited on stainless steel. Don't jump to the conclusion that gold film is less than desirable.

Many advantages exist for the use of PVD in watch and jewelry making. First, while only placing a thin film of gold on the surface, it's actually much tougher that electroplating. Secondly, it's inexpensive. Third, it allows manufacturers to put out a better product.

It's worth knowing that PVD coatings are harder and more corrosion resistant than coatings applied by the electroplating process.

Sellers

I find it somewhat irritating that people offer watches with PVD stainless steel cases and have no idea what it means. It's a term they throw around as if it means something special. As in, "this is a great watch, it's PVD!"

As Bill Murray might say, "the term is lost in translation."

Alloy watches

Before you get too scientific on me, I understand almost all steels are alloy - mixed with other metals. In manufacturing watch cases, however, alloy cases have a different meaning. We tend to think of an alloy watch as one that uses a mold.

Alloy Case

Two different process exist for making watch cases - metal injection molding and metal stamping and machining.

To create a material to inject into a mold, you have to have use a process to bind metal powder. That's accurate, alloy cases are made of powdered metal, which is heated and injected into a mold.

Alloy injection molding actually degrades the surface chemistry of metal. Metal stamping takes existing metal and uses it "as is". Stamping does not require mixing up a bunch of metal powder, heating it, injecting it into a mold and then reheating it.

When you look for a watch, you might see a specification that says 316L marine grade stainless steel. What they don't tell you is that it's really an injected "alloy" case using high grade stainless steel powder. This is an important distinction.

When I do a visual comparison of watch cases, I can immediately tell which process the manufacturer used. If the case has intricate patterns, it's more likely than not made in a mold. Manufacturers don't stamp out and machine intricate patterns and curves on watch cases. It requires human intervention and it's too expensive.

Stamped Stainless Steel Case

If a watch costs less than $100 and has a stamped screw-on back, I'm less critical of the product. I'm far less critical if the case stamp from a slightly lower grade stainless steel. The two most common grades of stainless are 304 and 316. The latter is marine grade.

How do you know?

I use a rule of thumb. If a new watch cost less than $100, I tend to believe the manufacturer used an alloy case. Exceptions do exist. For example, Parnis watches can cost you less than $100. Parnis sells through distributors who in turn sell direct to consumers. If you're in China and see a nice Mall, stop and look for a tiny store selling Parnis watches. If you find one, take advantage of the opportunity to buy a excellent timepiece inexpensively.

Back to my rule of thumb. If a new watch cost less than $100, then spend some time and use caution buying it. If you don't care about the quality and consider it a throw-away, then have fun. I'm just a little more discerning about timepieces.