Understanding "Denier"and Weave Catagories

 Normally this terminology is used when talking about stockings and pantyhose products that are 10 denier or below. They are normally used in the summer months as they are light and airy or for very special evenings out. This product is designed to make your legs look as if you're not wearing hosiery at all but is aimed at smoothing your legs and giving an even skin tone.  

You might be lucky to get more than one wearing out of these, as they are the most prone to snagging and running.  However, the newest and more expensive designer brands, have incorporated "run resistant" weaving technology, to prevent running, but they can develop small "snag holes" that can ultimately develop into runs if stretched.

They are constructed with the thinnest of nylon filament (think in terms of "silk" thread), and once normally ultra-sheer hosiery is designed to be worn with sandals or very strappy shoes. This makes them ideal for the summer months or for those gorgeous strappy sandals that you purchased for that big night out!  

This hosiery is generally between 12 and 20 denier, and most of the modern working women who desire some all day support, or a professional and business-like look, will choose this look. Obviously, the 20 denier products will be more durable than the 10 denier and will lend themselves to greater wear and tear. If you are undecided as to which finish to chose why not try matte for a flawless natural look or go for the glossy look if you want to get your legs on show!    
Most modern designer "luxe" pantyhose are in this category, and are generally 12 to 15 dernier, like Hue, Falke,  Wolford, Natori, as well as mainstream hosiery manufacturers like Hanes and Berkshire.   Spanx

Again these products lend themselves to be worn with sandals or strappy shoes given that they normally have a sheer toe, or the modern toeless pantyhose. 

 Products that are between 30 and 40 denier are usually termed as semi opaque. They are strong and will last a lot longer than sheers and yet your legs will remain quite visible. This hosiery is designed to give great coverage and can be purchased in an array of colors. 

 Between 40 and 70 denier, opaque hosiery gives a girl great coverage. You'll find it hard to see your legs through this fabric as it's thick and warm.

This product is perfect for chilly Autumn days. Coming in the most fabulous colors that can truly enhance your wardrobe. This product looks sensational with boots and skirts and can be worn for smart or casual.

 Normally 70 denier upwards, now where would a girl be without these? Winter brings with it all the frosty mornings and cold evenings. We all need to keep our pins warm at this time of year and never better with a product such as this. These opaque's are perfect for protecting your legs against the weather and are very durable and strong. 

Worn with boots, will be a stunning and stylish combination for fall/winter fashion.  

 These are worn for compression support for a variety of medical reasons, they've been found to reduce blood-clots in the legs during, and after surgeries, for prevention of varicose veins, etc.   

The choice of glossy, shiny, or matte finishes, depends on the occasion, event, or simply every day wear, as a reflection of the wearer's personal style.  

Shiny hose is a little more sexy or formal, and matte finish provides a flawless bare-leg look-- which is a matter of the personal taste of the beholder, as well as the wearer.  It is also, often a conundrum  as to which choice, so a a rule of thumb, if you want the "dress-to-impress" seductive look, go with the glossy/shiny, and for business and or daily attire-- matte is sufficient.

Also consider that shiny/glossy hose, is a thicker denier, so a little more durable, and less prone to snags and runs.

"Dernier"- is the key to measuring the sheerness, thickness, and opacity of tights and hosiery.  

From  Sheer to Opaque, a measurement and rule-of-thumb:

Unlike other garments, tights are conveniently classified by their material thickness, which is specified in the unit of measurement denier, or DEN for short. Think in terms of density-- the denser the material the more opaque, and the smaller the "D" rating, the sheerer the hosiery.  

See the scale of the classifications below-- from Ultra-Sheer, to warm thick opaque winter tights, or support or compression hose. 

The density of the stockings, pantyhose, or tights is cited in dernier (measured in density), which in other textiles, are referred to as thread count, etc.  

It consists of multiple (twisted) filaments that are thinner than the diameter of a human hair, to result in a thread, of varying thicknesses, comparable to anywhere from perhaps trout fishing line filament, to a nylon thread. Such thicknesses of different filaments and twisted yarns, although measureable in microns (micrometers) like a human hair or a silkworm silk strand, is easier measured in the established measurement methodology of the resulting weight per 30,000 linear feet of the filament or yarn-- in a roll. For understanding what a 30,000 foot roll of 1 dernier filament would weigh, what would you guess? That's almost the altitude that commercial jets fly! It would only weigh 1 gram (or 0.03527396 oz.)  

Such nylon yarn (the twisted filaments of nylon) generally between 8-10 dernier, can be a woven into the ultra-sheer[est]hosiery-- which although the absolute sheerest and transparent -- are unfortunately the most prone to snagging, and running. 

Every stocking wearing woman knows the agony of taking a brand-new pair out of the package, and snagging or running them before even having a chance to wear them!

In modern textile technology, the next consideration would be to twist multiple filaments into a more versatile elastic yarn, while still preserving the transparency, and sheerness.  These are blends of nylon twisted with other stretchable fibers like spandex, lycra, elastane and other polymide fibers to create a more durable yarn less susceptible to breaking by increasing the tensile strength. These yarns are dyed, and then woven into a gauzy transparent, or even a heavier opaque material  

From Wikipedia

Denier (/ˈdɛniər/)   or den (abbreviated D), a unit of measure for the linear mass density of fibers, is the mass in grams per 9000 metres of the   fiber.[The   denier is based on a natural reference: a single strand of silk is   approximately one denier; a 9000-metre strand of silk weighs about one gram.   The term denier comes from the French   denier, a coin of intrinsic value. Applied to yarn, a denier was held to   be equal in weight to 1⁄24 ounce (1.2 g). 

There is a difference   between filament and total measurements in deniers. Both are   defined as above, but the first relates to a single filament of fiber   (commonly called denier per filament (DPF)), whereas the second   relates to a yarn. 

Broader terms, such as fine  may be applied, either because the overall yarn is fine or because fibers   within this yarn are thin. A 75-denier yarn is considered fine even if it   contains only a few fibers, such as thirty 2.5-denier fibers; but a heavier   yarn, such as 150 denier, is considered fine only if its fibers are   individually as thin as one denier. 

The following   relationship applies to straight, uniform filaments: 

DPF = total denier / quantity of uniform filaments

The denier system of   measurement is used on two- and single-filament fibers. Some common   calculations are as follows:

1     denier = 1 g /9,000 m  

                        =  0.11 mg/m 

In practice, measuring   9,000 m (30,000 ft) is both time-consuming and unrealistic.   Generally a sample of 900 metres is weighed, and the result is multiplied by   ten to obtain the denier weight. 

• A fiber is generally considered a microfiber if it is one denier or less.
• A one-denier polyester fiber  has a diameter of about ten micrometres Micron: One millionth   of a meter, or one thousandth of a millimeter; about one-fourth the   width of a strand of spider silk. 

In tights   and pantyhose, the linear density of yarn used in the manufacturing process   determines the opacity of the article in the following categories of   commerce: ultra sheer (below 10 denier), sheer (10 to 30 denier), semi-opaque   (30 to 40 denier), opaque (40 to 70 denier) and thick opaque (70 denier or   higher).

The numbers are not chosen arbitrarily but represent the weight in grams that a thread has per 9,000 meters of length. For example, a 50 DEN tights weigh 50 g/ 9,000 meters. Fortunately, you don’t have to do any complicated calculations when choosing your tights, you just have to know how each DEN looks like and which DEN number is suitable for which temperature.

The most popular tights include thin tights in 20 DEN, semi-opaque in 40 DEN, and opaque for colder days in 80 DEN. In between there are many other variations that make it possible to choose the perfect tights for really every season.