Sunglasses: the materials of the frames

The choice of sunglasses is influenced above all by aesthetic preferences and only sometimes by functional reasons (for example polarized lenses, UV protection, sports models, etc.), but the more attentive consumer also wants to know the "substance" of what he is wearing. buying.

For this reason it is useful to know the characteristics of the materials used, in order to evaluate what best suits your needs and expectations of comfort.

So, what are the materials usually used to produce sunglasses frames? Which are the most classic solutions and which are the most innovative?

Most of the materials used to manufacture glasses can be traced back to two main "families": metal and plastic . However, there are other more "natural" solutions although not very widespread on the market, such as wood, bamboo and the even rarer horn.

The metal frames

The prerogative of these glasses is the resistance to mechanical stress and impacts which allows the creation of thin and robust frames . These are generally more durable glasses than plastic ones, on the other hand, being colored mainly through galvanic baths or particular lacquers, they are more subject to paint peeling.

The most "classic" metal is steel , sometimes enlivened with colored profiles in acetate or other plastic material (in these cases we speak of combined material). Steel is in itself very resistant, but to emphasize these characteristics, the addition of nickel is usually used, another element which can however generate skin allergies in predisposed individuals. In quality glasses, the potential problem is solved by coating the frame with special paints that prevent the metal from coming into direct contact with the skin. Alternatively, some manufacturers make frames using so-called " nickel free " alloys, i.e. steels where nickel is replaced by manganese or chromium.

Titanium is the alternative that is increasingly used for high-end glasses, also due to its higher cost compared to steel. In nature, titanium is dark grey, very light, hypoallergenic and extremely resistant. Compared to steel, however, it is less flexible and requires more complex processing; it is more difficult to weld and color, so the color range of these frames is quite limited. Lately, the use of Beta-Titanium has been spreading, an alloy that guarantees greater flexibility and workability, whilst maintaining excellent mechanical characteristics and notable resistance to corrosion.

Although used rarely and only for "special" models, gold and silver can also be used to make glasses, even if almost exclusively prescription glasses.

All types of plastic

The most used material nowadays is plastic, in all its variants: plastic is cheap, easily workable and in any case resistant enough to obtain glasses capable of withstanding most stresses.

Among plastic materials, acetate is certainly the most used to make frames, because thanks to its high workability it allows fashion houses to indulge in the shape and color of glasses. With acetate it is in fact possible to create a vast range of colours, textures and patterns, with bright and lively colours; it is also the only material with which it is possible to obtain the tortoiseshell effect so appreciated by many. As well as being resistant, it is also easily repairable with the appropriate tools; however, with heat it can slightly deform and over time it tends to undergo a progressive "aging" process.

Contrary to what one might think, it is also an "almost" completely natural and biodegradable product, as it is obtained from waste fibers from cotton and/or wood processing. The "almost" is due to the fact that the production process still involves the use of solvents and plasticizers (as well as dyes) to create the finished product. The growing environmental sensitivity of many consumers has recently promoted the development of 100% natural variants which, using exclusively natural additives, are totally biodegradable in a few months.

Decidedly less eco-sustainable is polyamide/nylon , sometimes also referred to as " injected plastic ". In this case it is a totally artificial product, very light, cheaper, resistant to mechanical stress and solvents.

It is a thermoplastic resin with a similar appearance to acetate. It is a very light material and resistant to most solvents. The appearance is similar to acetate, but the material is less resistant to impacts and with limited color variations. Consequently, to obtain particular colours, polyamide frames are painted and can therefore lose color more easily than acetate for which the color is usually added to the mixture. Due to its lightness it is very often used in the production of sports glasses.

Polycarbonate is also particularly suitable for sports or children's sunglasses because, in addition to being resistant and lightweight, it offers intrinsic protection against UV rays. It is a transparent and light-permeable material obtained from carbonic acid and therefore more eco-sustainable than polyamide.

Even if it is not strictly a plastic material, among the synthetic solutions we also mention carbon fiber , an extremely resistant and flexible fabric obtained by weaving a very thin graphite thread. The frames made with this material are very light and almost "eternal", but unfortunately quite expensive.

The materials "of the past"

Some materials traditionally used in past centuries maintain their own niche market. Among the most particular we find, for example, horn , a natural and hypoallergenic material, which allows you to have exclusive glasses as its color shades are unique and different from each other. However, it requires considerable maintenance to prevent dryness and cracking.

Another elegant material is certainly wood, in its many color variations: from cherry to oak, from walnut to ash. Wood is light and eco-sustainable, but rather delicate and not very resistant to impacts and humidity.

Used in Asian tradition, bamboo is the natural material most resistant to mechanical stress and completely impervious to water. However, it has limited workability and is often used in combination with other materials.