CHAPTER 1: FRAME ANATOMY
Below we define the Anatomy of a Sunglass and Eyewear Frames. Today, frame technology is as advanced as lens technology. The choice of design, size, material options, colors, and quality levels are vast. The structures, materials, and components used in the making of eyewear frames are many and each provides specific unique features and functionality.
There are countless frame designs having specific and unique features, we share below some key elements:
FRAME FRONT:
Frame fronts are categorized into three types that define the frame body.
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- Full frame fronts cover the entire edge of a lens. Lenses are fitted using an angled recess in the frame which is the lens groove.
- Half Rim frame fronts are half-frame, meaning the bottom edges of your lenses are exposed.
- Rimless frames have no frame front. Lenses are joined together via a metal or plastic bridge. The bridge connects and secures the lenses together to make the frame front. The lens is connected to the temples through the end-piece.
RIM:
Full-rim and half-rim frames have a rim. It can vary in thickness and is the home of the lens groove.
LENS GROOVE:
The lens groove is a continuous recess within the rim of the frame front and it holds the edge of a lens in place. Standard rim groove shapes are V and U.
END PIECE:
The end piece is where the temples are connected to the frame and the outermost side of the frame front.
BRIDGE (NOSE BRIDGE):
The bridge is a part of the frame and space that lean on the nose and allows the frame to rest on the face or saddle the nose. Of many, below are the most common:
- Saddle Bridge is a continuous, flowing shape that makes a U-shaped slot in the frame front. This style of bridge is very simple in appearance.
- Keyhole Bridges have a traditional style and look like a keyhole. This design distributes the weight of the glasses along the side of the nose instead of on top of it. This bridge style is more classic, originating with a full-rim eyewear design from the mid-century.
- Double Bridges first debuted in Aviator frames designed for military pilots. The bridge on aviators combined a saddle bridge with plastic nose pads between the lenses and a plastic or metal bar connecting to the top of frame creating the double bridge.
- Metal Bridges are used for either rimless frame fronts, full metal frames, or combo frames.
NOSE PADS:
The nose pads are the little humps or circular pads that rest on your nose. They are either incorporated in or added to the frame front. Nose pads can be fixed or adjustable.
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Fixed nose pads:
are nose pads that can’t be moved and are used in plastic and metal frames. They can be made of rubber or other materials and are part of or applied directly to the nose section of the frame.
- Integrated nose pads are part of the frame front. For acetate frames, the nose pads are laminated to the frame as separate clear pieces or they are sculpted as part of the frame. For injected frames, the nose pad area can be all one frame material with no rubber added or they are molded with a cavity that houses nose pads of various materials. Rubber nose pads can be flush with the frame or raised. For both frame types, other nose pad options are available.
Adjustable nose pads:
are just that adjustable. They are available in plastic and metal as a single unit mounted at the lower bridge area or mounted separately to each side of the nose.
- Sport
- Uni rubber nose pads are adjustable through an inner wire core and or thanks to a click system. The two main methods of attachment are by snap-on or by screw.
- Dual nose pad adjustability can also be achieved.
- Optical
- Pad Arms are little arms used to add nose pads to a frame front. There are a wide variety of types, shapes, and sizes to choose from. Nose pads can be set in with a small screw, snapped in, or slid in depending on the type of pad arm chosen. They are intended to allow for fit customization and comfort.
- Uni Metal is a U-shaped one-piece adjustable nose piece that houses the nose pads. It is attached to the inside lower bridge area of a frame or lens and can be permanent or removable.
TEMPLES:
The temples are commonly known as the branches or arms of your sunglasses. Most importantly, they keep the frame stable during use and play a key role in the fit and comfort of the frame.
- Paddle Temples or Bladed Temples are straight temples with no drop-end to hook behind your ear.
- Drop End or Hockey Stick Temples have end tips shaped like the end of a hockey stick. The drop-down occurs at the end portion of the temple (the temple tip) where it hooks downward to create a secure fit behind the ear.
- Curl or Cable Temples curl behind the entire rim of the ear providing a very secure and snug fit. They are more common amongst wire rim frames as the temples tend to be equally fine in thickness.
SIDE SHIELDS:
Side shields are half-moon-shaped parts that cup the end piece of the frame front extending to the temple and are most commonly used with 6 base frames. Essentially, they provide additional protection against solar radiation and elements such as wind, water, ice, and flying debris. Depending on the frame design and desired function, side shields can be removable or fixed as part of the frame.
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WIRE CORE:
Wire cores are one of the more discreet parts of a frame, often being entirely hidden within the acetate or injected temples. They are used to reinforce the durability of temples, and their shape, preventing deformation, and allowing for fit customization.
TEMPLE TIPS:
At the end of the temples are the temple tips can be in one with the temple or they can be integrated as additional parts providing specific functionality and or esthetics. Add-on temple tips are made in many forms, sizes, and materials.
- Acetate temple tips are usually part of the temple itself. However, they can also be added to the end of metal temples.
- Metal Temple Tips are usually covered or coated with plastic or rubber to make them more comfortable and easier to wear.
- Loop End Temple Tips are hollow loops that can be found at the end of a straight plastic or metal wire temple. These loops are to distribute pressure on the sides of your head and can also be used to attach a frame chain.
- Sleeve Temple Tips are slipped on the end of a temple becoming the temple tip. They are made from an array of materials and are formed in multiple sizes, shapes and textures, giving uniqueness to a frame. They provide fit comfort and adjustability depending on the material of the sleeve and frame design.
- Over-Molded Temple Tips – The first shot of an injected frame produces an eyeglass temple in a desired configuration having an entirely encased wire core. A second material can then be over-molded onto the temple tip. The over-molded material is usually a softer material that provides comfort and a more secure fit.
HINGE:
This mechanism connects the frame’s end piece to the temple and allows the frame to fold. Indeed, hinge hardware is a very important frame component because this is where most of the wear and tear on the frame occurs. Premium quality hinges usually mean quality products.
Metal:
- Barrel Hinges feature a series of figure-like (barrels) that interlock into each other with a small screw that slides inside to keep the barrels in place. The fingers of the hinge fit together to allow the hinge to open or close. The number of barrels used (three-, five- or seven-barrel hinges) refers to the number of interconnected barrels that comprise the hinge. The wider the temple, the more barrels the hinge needs to support its weight.
- Spring/Flex Hinges: There are two main types of spring hinges. The first is fully integrated, meaning the spring mechanism is hidden inside the frame. The second is external, with small springs that allow the temple to bend outward maintaining frame balance and a more customizable and secure fit minimizing.
- Interlocking Hinges are a lot like barrel hinges, except the hinge is molded directly into the frame and are also available with spring mechanisms. These hinges are commonly used in plastic frames.
Plastic:
- Pin Hinges connect the temple to the frame’s front end-piece via a screw or a pin.
- Pinless Hinges (Snap-in Hinges) are a lightweight alternative to metal hinges providing a smooth silent operation and have a flexible joint instead of a pin.
- CAM Hinges allow for a single or a double mechanical stop meaning that the hinge will close in one or two steps vs no steps.
RIVETS:
Rivets are cylindrical pieces of metal used to fasten hinges to the frame front or temples via a process called peening or staking and are parallel or tapered. They are usually made from soft metals such as steel, brass, or nickel alloy. If your glasses have tenon hinges, they’ll most likely be fastened via two or three little metal rivets. The rivets are in a tightly packed cluster on the frame’s front endpiece and the outside of the temple near the hinge. The number of rivets used varies between a two-cluster and a three-cluster formation, which is used equally for the frame and the temple.