Gloss - A Perception of Surfaces Part 2

Unlike other physical measurements, gloss measurement is not as straightforward. But it isn't difficult either, once one understood how gloss is perceived and interpreted by the human eye.

Gloss is an aspect of visual perception of objects, and it is an attribute of surfaces. With this in mind, any material could be made to meet the requirement of any gloss level as long as the technology exists and the method economic. 

What in this picture makes you think that the car's exterior is "glossy"? What causes this term to come to mind? (image taken from Ziebart)

Gloss - A Perception of Surfaces Part 1

You take a look at the shiny metallic surface of a sleek sports car and you immediately thought of it as "glossy". You saw another car with a body which reflects none of the ambient lighting, absorbing everything like a black hole, and you think of it as "matte".

The glossy surface of an Audi TT (image taken from DeviantArt).

As easy as the word comes to your mind, how does one define "glossy"? This would be important to an engineer, since there has to be some way to control the quality of a surface, and control will not be possible without measurement, and no measurement without a solid definition.

Analog vs Digital

One might have easily heard this hundreds of times - "We are now entering the realm of the digital age" or something along that line. What does that mean, and how much did "digital" influence our life?

To put it simply, a digital system presents data by using discrete or discontinuous values. In other words, there are only yes and no, 0 and 1. Or it may be 1, 2, 3, 4 and so on, but nothing is envisioned or accepted between the numbers, so there is no such thing as 1.4 in a discrete system. If the system is 1.1, 1.2, 1.3, 1.4 and so on, then 1.27 is not accepted within the system as well. You get the picture.

On the other hand, its counterpart, an analog system, uses continuous values for data presentation. Within this system, the data could be divided down infinitesimally. Not satisfied by the data value of 1.2, feeling that it is not accurate enough? Drill deeper and you may get 1.26. Deeper more and you may get 1.257. And so forth the value goes.

Resin Identification Code

If you were to flip over most everyday items made of polymer, especially those which are disposable, you would have noticed the triangular sign with a number within and maybe some alphabets below. This is the Resin Identification Code, and unless you were working with a disposable consumer item and your company is committed to label their product accordingly, you may not have given it  a second's thought.

Image taken from Flickr (by holeymoon)

In order to address the recyclers' rising need for a clear indication of polymer used, Society of Plastics Industry, Inc (SPI) developed and introduced the identification code in 1988. This code is usually found in packaging and containers since these are the main targets of municipal recycling programs, seeing that they are one of common items encountered within residential waste.

The code is used solely to identify the plastic resin in a manufactured item. In fact, the triangular label with 3 twisting arrows along with the number within are commonly misinterpreted. The number within is an arbitrarily chosen number to represent the target plastics, and has nothing to do with ease of recycling. A higher number does not mean that the plastics is harder to recycle.

Folding Plug

Ever thought of the fact that however portable and sleek your laptop or latest gadget is, the huge rectangular plug with its 3 bronze pins sticking out totally diminishes the definition of "sleek"? No matter how innovation is done on every part of an electronic device, the plug is the one with almost nonexistent change as far back as anyone could recall.

Folding Plug can, as its name suggests, be folded and carried with greater mobility (image taken from The Guardian).

IP Rating - Immersion vs Water Jet

Followers of this series of articles on IP rating will recall that a higher number on the 1st numeral will satisfy the requirements of a lower number (i.e. IP6X will mean that it passes all requirements from IP1X to IP6X, revisit here if the reader is interested). It would be prudent to note that such is not the case for the 2nd numeral.

An IPX4 test in progress. The semicircle apparatus sprays water through tiny nozzles lining the inner circumference. The apparatus is designed such that the water spray will reach the product from all directions. Notice that the spray is constrained to the top of the product, and the bottom is free from its direct effects (image taken from Qualilab).

The reason behind this is the difference in test requirement: 

• IPX1 to IPX6K, and IPX9K requires the product to be subjected to a flow of water impacting on the product 
• IPX7 and IPX8 requires the product to be immersed in a body of water.

In order to understand the test requirements, it is essential to first understand the application of the product in an environment prone to water ingress. Water ingress into the product could come in two different scenario - the product could be sprayed on by water jets, or it could be dropped into a body of water for a determinate period of time. It is possible to be subjected to both scenarios throughout the product's application lifetime as well.

IP Rating - Waterproof

Just as it would be difficult to judge the level of protection of "dustproof" products, the same applies to the term "waterproof" - it gives no indication the level of protection the product affords apart from the fact that it is protected against water ingress.

A waterproof iPod Stereo Case - how would you judge the term? Will the casing be free from water ingress if submerged for more than 1 hour? How will an engineer judge the term "waterproof" for critical engineering equipment? (image taken from Marine Audio and Stereo)

The 2nd code element of the IP rating helps shed some light on the level of protection, which is listed in the below table. The technical term usually associated to this code element is "protection against liquid ingress".