L13 Frame Materials Flashcards Preview

Opthalmic Lenses and Dispensing > L13 Frame Materials > Flashcards

Flashcards in L13 Frame Materials Deck (11):

Cellulose Acetate (plastic)

-fairly light - density 1.27
-always has reinforced sides
-adjust at 57 degrees celcius
- 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
- can be cut from a block or poured semi molten into a mould - this is stronger as the molecules arent cut
- solid colouring - thicker frames, bolder colours, can laminate with clear sheet for transparent colours
- lacquered and polished for shine
- discolours with age - can react with skin - white deposits and materials become rough to touch
- to recognise - colour all through and where sides meet frame front you can see it has been cut - rough edge


Optyl (plastic)

- epoxy resin registered by safilo
- side only reinforced for first 12mm - not really required, more decoration
- can be laminated or dyed then polished
- joints are injection moulded
- 30% lighter than cellulose acetate
- memory plastic - softens at 88 degrees - need to hold adjustment in place until it has cooled or itll return to its original shape


SPX (plastic)

-nylon based super-polyamide made by silhouette - always marked SPX
-sides always reinforced
-joints are injection moulded
- can be dyed or lacquered
- adjust at 95 degrees C - SHRINKS if overheated, cold glaze only
-impact resistant


Carbon fibre (plastic)

-nylon composite (20% carbon, 80% nylon) often with metal sides
-joints always pinned
- cant be heated - so cant adjust and diff to glaze
- v inflexible
- strong


Cellulose Nitrate (plastic)

-blocks of nitrate sliced into sheets
- sides always reinforced
-joints always pinned
- laminated or crystal (yellows quickly though)
- 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


Gold (metal)

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


Nickel Silver (metal)

-most common metal for frames - inexpensive
- contains copper, nickel, zinc and manganese
-parts assembled by soldering
-colour can be electroplated or lacquered (can wear off)
-easily adjusted
- some corrosion resistance
-nickel can react to skin


Nickel Titanium (metal)

-memory metal
-50% titanium
- only used for bridge and sides (not joints)
- 23% lighter than silver nitrate


Stainless Steel (metal)

- assembled by welding
- strong and flexible
- coloured by electroplating
- hypoallergenic
- corrosion resistance
- often no end tips
- rigid and flexible
- can be welded



- less widely used
- rigid so hard to adjust and repair (can only be laser soldered)
- shiny and can be coloured by anodising
-parts for frame all cut from one piece of material


Titanium (metal)

- mined as an ore - expensive. Then cut, pressed and laser soldered
- colour galvanised or ion plated
- hard to repair (needs computer controlled laser soldering at 1280 degrees)
- usually marked
-corrosion resistance