| Spectacle frame fashions undergo as many variations | | | | This material was developed and used for the |
| as hemlines have! | | | | production of glasses frames in the early 1920s in |
| Lens Materials | | | | France. Unlike its nitrate cousin this material was not |
| The mineral quartc is relatively weighty - another very | | | | flammable. It is a stable material and easily worked and |
| good reason for keeping the lens size down. These | | | | colored. It is still used today for spectacle frames. Over |
| days eyeglass lenses are generally made from | | | | time, if stored in overly hot conditions it will tend to lose |
| lightweight plastics called allyl diglycol carbonate. The | | | | its plasticity and elasticity, making it brittle and the |
| plastic's name is often abbreviated to CR-39, standing | | | | shapes to warp. |
| for Columbia Resin, and it is less than half the weight | | | | Perspex |
| of glass, which supplanted quartz in the early twentieth | | | | This very strong material gained popularity in the fifties |
| century. There are lighter spectacle lens option such | | | | and sixties for upswept cats-eye supra frames. These |
| as polycarbonate which is feather light and able to | | | | eliminated the lower frame rim, substituting a nylon cord |
| withstand heavy impact. Digressing slightly, it is the | | | | (like fishing line) which was held under tension in the |
| material of choice for vandal-proof light fittings. | | | | lower rim of the spectacle lens that had a groove cut |
| Unfortunately, although impact resistant, the material is | | | | to take the nylon cord. Although the nylon supra design |
| certainly not scratch resistant which is an important | | | | was strong, the material is very brittle, needing a great |
| quality to bear in mind when fabricating spectacle | | | | deal of heat before it can be adjusted to fit the |
| lenses. These days polycarbonate lenses, which are a | | | | person's face properly. If the frame is not sufficiently |
| feature of safety eyewear, are surface treated to | | | | hot it will snap and cannot be repaired. However it is |
| make them more resistant to scratching. | | | | actually relatively straightforward for the nylon cord to |
| Vintage Frames | | | | be replaced, should that break over time. |
| Most people want to collect vintage frames to wear | | | | There are various other materials such as carbon |
| them. There are a number of possible pitfalls to bear in | | | | fibre, which enjoyed brief popularity in the seventies, |
| mind. For example: | | | | but there is not enough space in this article to cover |
| What materials deteriorate? | | | | less popular materials any more comprehensively. |
| This is a slightly silly question as all frames deteriorate | | | | Are the frames safe to wear? |
| over time. Those the least susceptible to deterioration | | | | Well, with the exception of cellulose nitrate (see |
| are metal-rimmed frames. However with frames from | | | | above) yes, they are all safe. |
| around the mid twentieth century and onwards it is | | | | Can prescription lenses be put into a vintage frame? |
| common to find the end tips and the nose pads are | | | | Naturally every pair of spectacles must fit you |
| plastic coated. The core of such frames consists of | | | | properly. Some prescriptions are not suited to certain |
| nickel, which can set off marked reaction if it is contact | | | | frames, and the interpupillary distance (how far apart |
| with the skin (nickel dermatitis). End tips & nose pads | | | | your eyes are!) will influence how thin the lens can be |
| on such frames do deteriorate due to acid in | | | | at the edge. You will need to show your chosen frame |
| perspiration, but fortunately a good optical outlet can | | | | to your eyecare practitioner as it is possible to |
| generally fit replacement pads and tips - these may | | | | calculate the expected thickness of the lens edge for |
| not totally match the originals, but their positioning | | | | your prescription and frame chosen. |
| means they will be hidden behind your ears or behind | | | | Those frames with plastic rims need to be tough |
| the lenses. | | | | enough to be heated to stretch around the lens bevel, |
| Other eyeglass frame material fare less well. Various | | | | then able to shrink back to hold the lens securely. Your |
| plastics were utilised in the 20th century: | | | | eye care specialist / optometrist will be able to advise |
| Cellulose Nitrate | | | | on potential problems - glazing an old frame in this way |
| This material, first developed in 1850, was originally | | | | will probably only be undertaken at you own risk. |
| used for the production of movie film and for a short | | | | Opticians canot predict just by visual inspection how |
| while was used in spectacle frame production. | | | | fragile and brittle your vintage frame might be. |
| However it is essentially the same material as | | | | Reputable companies supplying vintage spectacles |
| guncotton (!) and it is now illegal to supply this, either in | | | | from the fifties will be able to give an indication on how |
| spectacle frames (or in films either). It deteriorates | | | | robust the frames are likely to be but it is likely that |
| over time, and with heat gives off an acid smell. Should | | | | they too will be able to offer any cast-iron guarantees, |
| it catch fire it produces its own oxygen and burns | | | | for the same reason. |
| really fiercely. This plastic decomposes over time and | | | | Vintage spectacle styles can undoubtedly give your |
| becomes dangerously inflammable. This material is so | | | | fashion sense a unique flavor. You may collect simply |
| dangerous that museums are not allowed to have | | | | for the joy of owning a piece of history, or for use in |
| examples stored or on display. You should defnitely | | | | costume drama, or to wear yourself, but whatever the |
| avoid nitrate frames! | | | | reason - good luck with your hunting! |
| Cellulose Acetate | | | | |