Frame Flashcards
What do we have to consider when looking at plastic materials?
- Consider how this will affect the fit- specific bridge styles
- Consider how it will affect adjustments – side length
What are the most dersiabrable properties of a frame used for the manufacture of a spectacle frame ?
Ease of production Lightweight and strong Non-flammable
Easily glazed and adjusted Good lens and shape retention Flexible
Inert to external agents and body fluids Cosmetically acceptable
What are some types of plastic frames?
- Cellulose acetate
- Optyl
- SPX
- Cellulose propionate
- Acrylic/PMMA
- Carbon Fibre
What are some properties of cellulose acetate?
- Inexpensive
- Fairly light- density 1.27
- Always has reinforced sides
- Adjust at 57degrees
- Needs reinforcement or can warp and become soft
- Joints can be heat inserted, pinned or screwed
- Can react with skin- can be metal joints so can lead to rash.
How can cellulose acetate frame be cut?
Can be cut from a block or poured semi-molten into a mould- this is stronger as the molecules are not cut.
What are some more properties of cellulose acetate ?
- Solid colouring- thicker frames bolder colours, can laminate with clear sheet for transparent colours
-colouring achieved by water based dyes
- Lacquered and polished for shine.
To recognise- colour all through and where sides meet frame front you can see it has been cut- rough edge.
What is a disadvantage of the cellulose acetate?
- Discolours with age- Can react with skin- white
deposits and material becomes rough to touch
How is the cellulose acetate plastic adjusted / fitted?
- forced in a semi- molten state into a mould. This latter method gives a stronger frame, as the fibres, or molecules, are not cut through, but bend around curves.
What are some properties of optyl?
-Epoxy resin registered by -Safilo- always markedΩ
- Side only reinforced for the 1st 12mm- not really
required- decoration.
- Can be laminated or dyed then polished.
-Joints are injection moulded
- Hypoallergenic
- 30% lighter than cellulose acetate
-Memory plastic- softens at 88degrees- need to hold adjustment in place until it has cooled or it will return to its original shape
What are some properties of SPX?
-Nylon based super-polyamide made by Silhouette- always marked SPX
- Sides always reinforced
- Joints are injection moulded
-Can be dyed or lacquered
-Adjust at 95oc- beware!
-Shrinks if overheated- ‘cold glaze only’.
- Impact resistant
- Flexible
-lightweight
What are some properties of cellulose propionate?
-Often marked with CP
- Sides always reinforced
- Joints are injection moulded around hinges
- Can be dyed or lacquered after cutting so where side meets front is smooth
- Adjust at 67-70oc Beware! Shrinks if over heated so ‘cold glaze’
- Good stability- but hard to adjust
- Lightweight
-Hypoallergenic
What are some properties of Acrylic/PMMA?
-Sides unreinforced, often metal
- Joints are pinned
-Frame front usually laminated, sides dyed- bright colours used
- Very brittle so only used for supra styles (often upswept)
- Needs to be heated to a high point before any adjustment therefore hard to adjust
What are some properties of carbon fibre?
Nylon composite (20% carbon, 80% nylon) often with metal sides
Joints always pinned
lacquered
Cant be heated- so can not adjust and difficult to glaze
Very inflexible
Strong
light
What are some properties of cellulose nitrate?
Blocks of nitrate sliced into sheets
Sides always reinforced
Joints always pinned
Laminated or crystal (yellows quickly though)
Beware- highly flammable!! DO not adjust
Smells of camphor if scratched (if in doubt test in an inconspicuous place)
Joints can rust and turn green
Brittle- can crack with age
What do you consider when looking at metal frames?
- Consider the fit- the style of bridge
- Consider possible adjustments
What are some properties of gold?
Gold filled- Fraction of gold content marked in parts per 1000 marked on the bridge.
Rolled gold- Has a base metal (nickel silver/ bronze) core. Gold content encircled and marked on the bridge or the sides.
Keeps colour well Soft
Resistant to corrosion
Hypoallergenic unless underlying base metal exposed.
What are some properties of nickel silver?
Most common metal used for frames- inexpensive
Contains copper, nickel, zinc and manganese (no silver!) Parts assembled by soldering
Colour can be electroplated or lacquered (can wear off) Easily adjusted
Flexible
Some corrosion resistance
Nickel can react to the skin
What are properties of nickel titanium ?
Memory metal
50% titamium
Only used for bridge and sides (not joints) 23% lighter than silver nickel
What are some properties of stainless steels?
Assembled by welding Strong and flexible Coloured by electroplating Hypoallergenic Corrosion resistance Often no end tips Rigid and flexible Can be welded
What are some properties of aluminium ?
Less widely used
Expensive
Lightweight
Rigid so hard to adjust and repair (can only be laser soldered)
Hypoallergenic
Shiny and can be coloured by anodising
Parts for frame all cut from one piece of material
What are some properties of titanium?
Mined as an ore- expensive. Then cut, pressed and laser soldered. Colour galvanised or ion plated Up to 50% lighter than silver nickel Hard to repair (needs computer controlled laser soldering at 1280 degrees!) Hypoallergenic Flexible Usually marked Corrosion resistant
What re some properties of tortoise shell ?
Now illegal! But still seen occasionally Natural material made from Hawksbill turtles Stable Adjusted using steam If broken- can be spliced using another piece of shell and steam Joints always pinned Sides unreinforced Metal joints
