EJ's Reference Guide
EJ's Suggested Use Specifications:
To better help you compare models and find glasses for particular uses, we've developed a list of specific keywords for "suggested use" of each model we carry. Please be aware that these are just suggestions and particular models may work well for other uses besides those listed, and your own personal preference for usage may be different than ours. That's OK!
Just be aware of your own safety when choosing sunglasses for particular purposes (We couldn't recommend a model with stiff metal frames and glass lenses for high speed sports like skiing or racing motorcycles...). Here are the keywords you can search for and the definitions we use for each:
Lens Types and Materials:
Here is a list of definitions used in EJ's "Lens Type" specifications.
Polycarbonate-
Polycarbonate is a light weight lens material that has the highest impact resistance
of any lens material available in a sunglass. In fact polycarbonate lenses are 10
times more impact resistant than conventional plastic or glass lenses.
Polycarbonate lenses are also much thinner and lighter than glass or plastic
lenses. If you use your sunglasses in any situation
where there is any chance of an impact to your eyes, polycarbonate should
be your only choice! Gargoyles, Smith, Adidas and Wiley-X lines are made exclusively with polycarbonate lenses.
Melanin-
Melanin is a natural substance found in our skin, hair and eyes that provides a powerful defense against harmful exposure to sunlight. It goes beyond uv protection by also significantly reducing the amount of high energy
visible (HEV) light, thereby reducing the risks of macular degeneration. Problem is, it breaks down over time, leaving you less protection.
Melanin lens system replaces your eye's Melanin
which is lost with age. It will not wear out, rub off, or lose its
protection value over time.
CR-39-
CR-39 is the trade name for the plastic that has become the standard
in the optical industry. CR-39 lenses are much lighter and less breakable
than glass lenses, but not as impact resistant as polycarbonate. Be sure to check out the Costa Del Mar line for more information.
Glass-
Glass is the heaviest lens material available, but it also has the
best scratch resistance available. Glass must be hardened by chemicals
or heat tempering to meet U.S. Food and Drug Administration standards for
impact resistance. Glass has the best optical clarity of all the lens materials
and many purists swear by it. Many of the leading polarized sunglass manufacturers
such as Maui Jim, Ultrasol, Action Optics and Hobie use glass lenses in some or all
their lenses.
Interchangeable-
Frames with interchangeable lenses allow for easy switching of the "in-use" lens with a replacement lens. This could be done by simply popping out the lens from the frame (Wiley X has a few models that do this), or by designing the frame to allow the lenses to slide in and out (check out the Smith Slider series or the Gargoyles Legends series).
Most models with interchangeable lenses come with additional lenses already in the price of the sunglasses, or you can typically find "Replacement Lenses" as an accessory item for these models.
Anti-Fog-
Usually associated with ski and swim goggles, anti-fog lenses have a special clear coating which dissipates the water droplets that form the "fog" on the inside of your lenses during strenous activity. Some goggles will also have a venting system (usually in the form of small openings along the side) to aid the no-fog process. Many of our ski goggles are no-fog (Killer Loop, Bugz and Bolle are prime examples),
while all of Barracuda's swim goggles are anti-fog, and Coyote makes a few active wear sunglasses with a no-fog coating.
Lens Polarization-
Polarized lenses have the benefit of filtering out reflected light
and glare off water, pavement and snow. This lens works great for fishing,
boating, driving or any other glare intensive activity. Polarized lenses
are the best way to eliminate both glare and UV light. The principle of
a polarized lens can best be described by observing the use of a venetian
blind. The blind blocks light at certain angles, while allowing light to
transmit through select angles. Polarization is achieved by shutting out
100% of undesirable light and allowing 100% of desired light through the
lenses. Many polarized lenses feature AR coating on the back of the lens
for even better clarity and reduced back glare
(Anti Reflective (AR) Coating is an extremely thin layer of film that is
deposited on either the front or the back surface of the sunglass lens
that virtually eliminates reflections from the back of the lens). Be sure to check out the nice polarized lines from Maui Jim, Native, Costa Del Mar and Ocean Waves
Photochromatic Lenses-
Photochromic lenses have an adjustable tint that changes with the amount
of available light. In bright sunlight they darken; when light conditions
are not as bright, they lighten in color. Note that the photochemical response does not happen instantaneously. It normally takes (on average) one to two minutes for photochromatic lenses to adjust from very low levels of light to very bright and vice versa. Also, the tint change is usually not very dramatic. Photochromatic lenses usually range from 10% light transmission in bright light to 20% light transmission in low light. A difference of 10% transmission is not always noticeable, but over long periods of time, you should notice a significant reduction in eye strain.
As a general rule, photochromatic lenses are almost always glass lenses due to the nature of the photochemical application process. Hobie and Action Optics both make a photochromic-polarized lens, while Serengeti makes all of their Drivers lenses photochromic.
Mirror-Coating and Mirrored Lenses-
Mirror coating is like the name indicates, is a mirror coating applied
to the front surface of the lens. A special treatment is applied to the
front surface of each lens through a vacuum process that allows the lens
to take on the properties of a two-way mirror. Mirror coatings can reflect
the light rays that are emitted from surfaces such as water, snow and ice
therefore making the lens darker than an average un-mirrored lens. Many
Mirror coated lenses may also feature AR coating on the back of the lens
for improved vision and reduced back glare. Mirror coating can be applied to almost any kind of lens material. Check out these lines for more lenses with mirror coatings Bugz, Bolle, and Adidas
Ultraviolet Protection:
You may have already heard about the horrible effects of overexposure to ultraviolet radiation: Melanoma and skin cancer, increased risk of cataracts, etc. Thankfully, ultraviolet radiation is a high-energy, lower-wavelength radiation (higher than that of visible light, hence the "ultra-" in ultraviolet) and as a result, it is easily reflected. The ozone layer of the earth's atmosphere reflects most of the UV radiation from the sun back into space. Closer to the ground, we can rely on glass windows to reflect up to 90% of direct UV radiation, and special chemical coatings can
increase this to virtually 100%. Thus, it is relatively easy to protect one's eyes from the damaging effects of UV radiation, just by wearing sunglasses! Almost every model we carry will deliver a near 100% UV protection rate. More specific information is available depending on the manufacturer and model.
Frame Types and Materials:
Here is a list of definitions used in EJ's "Frame Type" specifications.
Metal Frames
Monel-
This is the traditional metal used for most sunglass frames. Monel
is an alloy containing nickel, copper, iron and other trace elements, with
nickel being the primary component (at 63-70%), followed by copper and
then iron (at only 2.5%). This material is pliable making it easy to adjust.
It holds its finish well, however, it is more susceptible to corrosion
and more apt to cause allergic reactions due to its high nickel content.
Many of the sunglasses at EJ's Sunglasses feature Monel frames, due to
its great durability.
Stainless Steel-
Stainless Steel is made primarily from Iron and Chrome. It is a very
strong metal alloy. Stainless steel frames can be made very thin
and still maintain their strength and great flexibility. Like Titanium,
it contains no nickel, therefore it is virtually hypo-allergenic and resistant
to corrosion.
Titanium-
This is a premium frame material. Titanium is stronger, with twice
the tensile strength of traditional metal frames and is 48%
lighter. Titanium is also 20 times more resistant to corrosion and is hypo-allergenic,
due to the fact that it has no nickel. Check out the Maui Jims line for a large
selection of titanium sunglass frames.
Aluminum-
While aluminum was once very popular, and is strong and light, it is
not used quite as much, as it does not weld or solder easily and is somewhat
difficult to adjust. Aluminum does have a very unique look and feel to
it. Be sure to check out the Gatorz line, as all of the their frames are made
from aluminum.
Plastic Frames
All of the plastic frames at EJ's Sunglasses can vary from brand to brand. (Some manufacturers don't even list the kind of plastic that the frame was made from) If you need to know exactly what the frame is made of, simply contact us and we will do our best to find out for you.
Optyl-
Optyl is the trade name for an epoxy resin which is drawn into molds
while in its liquid state to make frames. This material is "thermoelastic"
meaning it will bend when heated but will return to its original shape
when heated again. This quality does make the frame more apt to come
out of adjustment if exposed to hot temperatures.
Zyl-
This is a term used for a variety of plastic materials used in
making frames, the most common of which is Cellulose acetate. Cellulose
acetate is made from a cellulose material extracted from cotton or wood
pulp mixed with anhydride acetic acid, plastisizers and aging stabilizers.
This material can be shaped into frames in two ways. It can be formed into
sheets from which frames are stamped, or it can be injected into frame
molds. It comes in a very wide range of colors with good color
stability and is easily adjusted. Some people have allergic sensitivity
to zyl frames. This is less likely with high quality zyl frames, which
usually have an additional protective coating that prevents fading and
UV damage to the frame material.
Polycarbonate- (frames)
Frames made from polycarbonate are primarily associated with sport
or safety glasses. Polycarbonate is also used for nonprescription shields,
where the lenses and frame are molded in one unit. It is also the material
used in the type of sports frames held on with elastic straps. In combination
with polycarbonate lenses, this material offers optimum impact resistance
and eye protection. This material can not be adjusted very well.
Carbon fiber-
This material is made by weaving carbon fibers and nylon togther and while
this creates a thin very strong material, it is not very adjustable.
Carbon fiber does have a very distinct look and feel to it. Many sunglass companies make a faux carbon fiber frame, to acheive this
they use a painting process to give the frame that "carbon fiber" look.
Check out the Bugz
soft touch line to see an example of this.
Co-Polymide-
This nylon based material is quite strong, can be made thinner and
is approximately 30% lighter than traditional zyl frames. Co-Polymide is
available in a wide range of colors. It is resistant to chemical damage,
and is hypo-allergenic, however it is also somewhat resistant to adjustments.
Hinge Types:
Here is a list of definitions used in EJ's "Frame Type" specifications.
Barrel-
The most commonly used type of hinge. Interlocking pieces found on the inside face of the frame are kept together with a small screw.
Some adjustability is available with some models. Be careful not to lose the screw!
Interlocking-
Very similar to the barrel hinge, but the hinge is actually part of the frame itself. Usually found in plastic frames, the joint is molded into the frame pieces and
there is no separate hinge pieces holding the frame together. Once again, try not to lose the screw!
Spring-
Spring hinges use a spring tension to press the temples of the frame closer to the sides of your head. This allows for a closer, more
customized fit. As a result, models with spring hinges are usually more expensive, but they are probably the most advanced hinges money can buy.
Many high-end models like Maui Jim and Revo have
spring hinges.
Break-away-
These hinges are made from interlocking plastic parts that "break away" or separate when a significant impact from the outside occurs. If you've ever been
hit in the face when wearing a pair of glasses, you may already know the damage the frame may cause to your face during impact. These hinges, found mostly
on sport sunglasses, will prevent that damage from happening again, and in fact, allow the frame to absorb some of the impact to lessen the blow directly upon
your face. Adidas is the largest manufacturer of models with breakaway hinges.
Stainless Steel-
If the hinge is made out of stainless steel, we will try to indicate so. You can expect a longer life out of steel hinges over plastic, but less flexibility as well.
