Unit 1 Flashcards
before 1200s
used glass spheres filled with water to magnify thigns
1200
used rock crystal into convex shapes for reading. “lapides ad legendum“
Furthermore these craftsmen also made crystal discs which were called “roidi da boticelis“, i.e. glass plugs that were used to close jars containing precious ointments.
what did Luigi Zecchin do in 1200s
by putting the eyes near one of the discs, all objects became clearly visible. In any case, in 1284 the “roidi da ogli“, “round glass for the eyes“, are present in the list of routine production items.
1300
Reading glasses- craftsman allowed to make
-Discovered colorless glass
-the first eyeglasses were made with round biconvex lenses, to improve farsighted vision. They consisted of two lenses; each assembled with a rim of metal or of wrought leather, riveted together at the end of each handle.
1400
Biconvex lenses held w/ hand
-No temples
-Only for reading or hyperopia
1500
4 Materials were used to manufacture the frames; Whalebone, horn, tortoiseshell and leather
-Spring bridge type
-First guild regulations
1600
Development of the wire drawing, metal frames (especially copper) because the cost was so low.
-Greater distribution in the marker for shaping of the bridge.
-Ribbons were being tied from the end of lenses to the back of ears
-Bar that was attached that would be held up by a wig or hat
-In 1623 Deca De Valdes did the scientific table, diopters.
1700
Temples glasses (Edward Scarlett)
-Bifocals or Split lenses
-Upper half corrects myopia
-Lower half for presbyopia
-Used as an accessory by the French
Fun fact; Chinese frames don’t have a nose piece b/c of nose shape & made of tortoise shell; easy to work with
1800
Pince-nez was the most popular eyewear (1830)
-Thin metal temples
-Temples wrapped around the ears
-1873; John Wesley Hyatt
-Pattened Celluoid and Bakelite
-Different shapes due to frame materials
1900-present
Increase production and transportation which lead to more glasses being made
-1910s celluloid frames (flammable)
-Expression of styles and personalities
-Polarized lenses
-Progressive lenses
-Plastic frames created in 1950s-1980s
-Photochromic lenses
-Blue light lenses
-2000s italian eyewear = world leader
-Google glasses, sunglasses
snow goggles
-Protect your eyes from the reflection of snow (UV)
-Protect from snow blindness
Frame Materials - Plastic
Bakelite and Galalith – 1st (very brittle, especially with cold)
Cellulose Nitrate – banned by the FDA for being highly flammable
Cellulose Acetate – cotton or wood pulp, generally milled into sheets, but it can be used as granules for injection moulding (brittle with age)
Cellulose Aceto –Propionate - better than acetate for injection moulding
Optyl – Epoxy Resin, thermoelastic (bend when heated, and return to it’s original shape when reheated.
Nylon – Highly Flexible, but must be soaked in water overnight occasionally.
Polyamide/Copolyamide – Nylon based, very strong, 72% of the weight of Cellulose Acetate. Hypoallergenic
Grilamid – Nylon based, large variety of colours
Frame Materials - Metal
Bronze – Metal alloy copper and tin. Lightweight, corrosion resistant
Magnesium – lighter than titanium. Exceptionally durable. Exterior of the frame should be sealed, otherwise raw magnesium is very corrosive
Aluminum – Strong and Lightweight. Does not solder or weld well. Has no flexibility
Stainless Steel – Can be made very thin for springiness and flexibility. Relatively non-allergenic
true or false
people tend to be allergic to nose pads (silicone)
true
lens material
**Plastic
- CR 39 – Regular plastic lens
- 1.6
- 1.67
- 1.74
**Polycarbonate- most impact resistance lenses available
**Trivex – most impact resistance lenses available
**Glass (not many places sell it anymore) - 1.53- crown glass
- 1.6
- 1.7
- 1.8
- 1.9
*higher the index of refraction the thinner the lens.
