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DISPENSING > Frame > Flashcards

Frame Flashcards

1
Q

What do we have to consider when looking at plastic materials?

A
  • Consider how this will affect the fit- specific bridge styles
  • Consider how it will affect adjustments – side length
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2
Q

What are the most dersiabrable properties of a frame used for the manufacture of a spectacle frame ?

A

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

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3
Q

What are some types of plastic frames?

A
  • Cellulose acetate
  • Optyl
  • SPX
  • Cellulose propionate
  • Acrylic/PMMA
  • Carbon Fibre
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4
Q

What are some properties of cellulose acetate?

A
  • 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.
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5
Q

How can cellulose acetate frame be cut?

A

Can be cut from a block or poured semi-molten into a mould- this is stronger as the molecules are not cut.

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6
Q

What are some more properties of cellulose acetate ?

A
  • 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.
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7
Q

What is a disadvantage of the cellulose acetate?

A

-— Discolours with age- Can react with skin- white

deposits and material becomes rough to touch

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8
Q

How is the cellulose acetate plastic adjusted / fitted?

A
  • 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.
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9
Q

What are some properties of optyl?

A

-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

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10
Q

What are some properties of SPX?

A

-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

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11
Q

What are some properties of cellulose propionate?

A

-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

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12
Q

What are some properties of Acrylic/PMMA?

A

-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

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13
Q

What are some properties of carbon fibre?

A

— 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

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14
Q

What are some properties of cellulose nitrate?

A

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

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15
Q

What do you consider when looking at metal frames?

A
  • Consider the fit- the style of bridge

- — Consider possible adjustments

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16
Q

What are some properties of gold?

A

— 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.

17
Q

What are some properties of nickel silver?

A

— 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

18
Q

What are properties of nickel titanium ?

A

Memory metal
— 50% titamium
— Only used for bridge and sides (not joints) — 23% lighter than silver nickel

19
Q

What are some properties of stainless steels?

A 
— Assembled by welding
— Strong and flexible
— Coloured by electroplating — Hypoallergenic
— Corrosion resistance
— Often no end tips
— Rigid and flexible
— Can be welded
20
Q

What are some properties of aluminium ?

A

— 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

21
Q

What are some properties of titanium?

A 
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
22
Q

What re some properties of tortoise shell ?

A 
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

DISPENSING (19 decks)

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