PropionateHome Propionate material meaning Opticians Support Staff. Promotions Links News Archive. No material can meet all these requirements perfectly however and so f rame manufacturers are working hard to keep up with lens technology to provide us with the best choices of features and benefits for both function and fashion. As newer materials are introduced, there is an ever growing choice for every patient, from the person looking for lightweight simplicity, to the sports participant in need of increased flexibility, safety propionate material meaning fit. Rolled gold, invented by jewellers, describes a material created by bonding a layer of 14Kt gold to a durable base alloy on to which a propionate material meaning coating of 24Kt gold is applied.
Eyeglass Frame Materials - writingdesk.pw
When looking at supplying a frame to a patient, not only must we take into account the fitting, the style and the cosmetic effects, we must look very carefully at the material that is used. The art of ensuring the best pair of spectacles is dispensed does not stop with the lens choice; it must be extended to the design and the material of the frame.
It is imperative, particularly with many modern day materials being notoriously difficult to adjust, that the patient is appropriately advised and measured to ensure a good fitting frame at the end of the dispensing process. It is therefore as important to assist with the choice of frames as it is to assist with the lenses. When offering advice on lenses, we do not give the patient a catalogue and say take your pick. Strictly speaking, precious metals such as pure gold and silver fall into this category and have been employed as frame materials.
These will be dealt with under metals. There is a wide array of non-metallic natural materials, some undergoing something of a renaissance as manufacturing and stabilising techniques improve. Here are just a selection;. Materials used for the manufacture of spectacle frames are therefore generally thermoplastic. Some materials such as the epoxy resins Optyl are said to be thermoelastic. Other plastics materials used in frame manufacture include nylons, composite materials and silicon.
This was one of the first plastics developed and was widely used in frame manufacture until its use was prohibited in many countries, including the UK, due to flammability issues. It is characterised by its toughness, high shine and the ability to retain its shape and stability in hot, humid climates. The material can be softened and adjusted but with a flash point of 90oC, just above its softening point, extra care has to be taken. It yellows with age and some practitioners claim that it smells of moth balls when heated.
Although practitioners may still make adjustments to frames manufactured using cellulose nitrate, the dispensing, glazing or re-glazing of this material is now prohibited. This is a non-flammable thermoplastic polymer. It was developed in response to the problem of flammability with the nitrate. It is comprised of a base of cotton fibres, mixed with acetic acid figure 6. It is used for spectacle frames in one of two forms:. The colour of the frame is a solid colouring that is achieved by water-based dyes figure 7.
Thicker materials therefore have a denser colour to them. Light colours can be assisted by the use of two sheets of acetate, one coloured and one crystal, being fused together. This is a common technique used on sides, with the two parts grooved ready for the reinforcement wire such that when they are fused together the wire is contained within. After the frame is constructed, it is polished using a barrelling technique. Modern frames are treated with a high gloss polyurethane lacquer to give an increased resistance to scratching.
The frame is not hypoallergenic, with many patients experiencing a mild allergic reaction. These responses may cause a minor rash or irritation, and lead to frame discolouration. Prolonged wear of cellulose acetate frames can cause the frame to whiten, and appear cracked and rough to the touch.
This will happen most frequently where there is direct contact between the skin and the frame, typically over the bridge and along the inner surface of the sides. The material, if used without the reinforcement, is fairly soft and can warp quite easily, especially if maltreated or left on window sills or car dashboards. This is due to the lack of shape-memory.
The older the frame becomes, the easier it will warp. This warpage needs correcting and this will required more frequently the older a frame is. An older frame, say beyond 12 to 18 months old will need regular maintenance. It will not burn. The reinforced sides of this material give a clue to its identity.
The end of the side that rests on the front is rough to the touch, due to the side being cut to fit, and the colour can be seen all the way through the side. The density of this frame is 1. This is a thermoplastic material made by mixing cellulose flakes with propionic acids. In its raw state this material is in the form of small transparent beads that are heated in order to fuse them together. It is then poured into a mould, which usually has the joints and reinforcements pre-placed so giving added strength.
The material is therefore classed as injection moulded. The colouring is by dying but the material will only accept the dye to a depth of a few microns so it is only a surface dye. When folding the side down, and looking at the end which touches the front, the side can appear clear.
The colouring technique enables intricate designs and patterns to be added. When the side is folded down, the area that is rough on an acetate frame is smooth on the propionate frame due to the lacquering taking place after the frame has been cut and shaped.
It offers greater stability than acetate and is much more resistant to warping and fading than acetate, so ages far less rapidly. It is less allergenic than acetate, but not entirely so due to the nickel content of the reinforcements and joints. The hypoallergenic properties are assisted by the lacquer. If this coating is cracked during adjustment, then allergies may increase. Propionate has a density of 1. When working with this material, the initial fit of the frame needs to be very good, as there is little useful adjustment that can be made later.
This was used to produce lightweight, transparent or dyed frames that were stable and yet flexible. With a relatively high softening point the material was not as easy to work with and shrank or distorted if overheated. This material was popular in the s and s when it was used to manufacture supra frames. This thermosetting material is probably the most versatile of all frame materials but, alas, one that is out of fashion as it is wrongly perceived as one that is difficult to work with.
It is a form of epoxy resin that is made by injection moulding during which the polymerisation takes place. Some will tell you that the reinforcement is only applied for the first 25mm of the side, whilst others argue that it has no reinforcements at all. In truth, the material does not need reinforcement, but some frames have this as a decorative addition. The main advantages of this material are its hypoallergenic properties, making it dermatologically safe, and its thermal memory.
This is an extremely useful aspect of the material as, once Optyl has been correctly adjusted, it should never need readjusting. It holds the shape at which it has been set. Heat renders the material extremely pliable. If, however, the frame is reheated to the same degree and allowed to cool naturally and without being held in place, it will return to its original shape. Quite useful if you make a mistake!
The coloured dye is a few microns deep on the surface which then has a lacquer applied for a highly polished look such that, when you look down the length of the side, no colour can be seen. This lightweight material, with a density of 1. It is quite resistant to scratching. Optyl should not be cleaned using spirit based materials as these can and often do break down the lacquering. Optyl is the only material that was designed specifically as a spectacle frame material prior to being used in other areas.
This thermoplastic material is mainly used in the production of sun-spectacles and industrial safety spectacles. The main production is by injection moulding and the colour can either be added into the base material or painted after the frame is finished.
Dyeing the base material will have a longer lasting effect. The finished frame is then lacquered for a high quality sheen. The material has good tensile strength and pliability. Pure nylon is usually only available in single solid colours and with a limited shine due to the nature of the material.
However, a mixture of nylon and carbon fibre can be used to improve the surface finish and also assist with tensile rigidity. Metal sides are preferable to give easier adjustment which will be longer lasting than trying to adjust nylon which springs back into shape too easily.
It is not advisable to heat nylon due to excessive shrinkage that will result, at the very least, in the material undergoing a breakdown of the fibres so reducing strength considerably. Nylon has a good plastic memory and this also reduces the chance of getting a good adjustment. A density of only 1. All forms of nylon will shrink and lose stability if overheated.
Nylon, along with any material that can be powdered, can be used for 3D printing of frames figure This is a co-polyamide nylon derivative, which is exclusive to Silhouette.
However, not all Silhouette frames are SPX. Any temperature below this means the material is too cold and becomes brittle. Above this temperature, the molecular structure starts to degrade.
This starts with the molecules separating, and elongating into strands. The material takes on a furry appearance as it starts to shrink and will eventually pull apart. However, like Optyl, it is hypoallergenic and it neither corrodes nor erodes. The nylon aspect of the material makes it very flexible and also hard to scratch.
The colour is introduced by dyeing the base material followed by painting and lacquering the outer surface. In the early days of production, SPX fronts often had SPX sides, which resulted in some awful adjustments and uncomfortable spectacles. Extruded acetate and cellulose propionate are both now used.
This material was originally called Grilamid, and is a derivative of amorphous co-polyamide. Due to its high tensile strength, a sofyl frame requires less material and is therefore thinner and subsequently lighter. It is flame resistant and hypoallergenic.