Japanese Eyewear Manufacturing: Everything You Need To Know from Start to Finish

 

japanese eyewear manufacturing

 

How did Japan end up making eyewear?

Production of eyewear in Japan was traditionally done in Tokyo and Osaka. Fukui, now the primary eyewear production center in Japan, is on the west coast, the “backside” of Japan (as is Niigata, where we are located as well). The backside of Japan was very isolated (and in some ways still is), the mountain range that runs down the middle of Japan distanced it from the economic centers of Tokyo and Osaka, that same mountain range also stops the clouds which form by cold/dry air currents coming down from the north and pick up water from the warm northern flowing currents of the Japan Sea. Snow is deep, winters are gray and long. The area was mainly farming and fishing, in order to lift the people from poverty and give them something to do in the long, gray, snow covered winters. Craftsmen were brought from Osaka at the turn of the 19th century to teach eyewear production to keep people busy and provide extra income. The industry grew and constant advancements and drive for perfection gave rise to the Japanese eyewear manufacturing industry of today.

 

What are the main key differentiators in Japanese frames? Materials, process, etc.

What makes a “Japanese” frame special/different? Attention to detail. The polish, the fit and finish–things that are hard to measure. Current manufacturing equipment and processes can do extremely precise work.

Equipment sets in China and Italy are often newer and better than those found in Japan, but it is the endless drive for perfection, never being satisfied with “good enough”, that brings Japanese frames to life.

There are other differences as well. “Japanese” acetate is harder, it contains less plasticizer, the material in acetate which makes it flexible. Your screwdriver handle is made of acetate. Pulp and cotton which has been reacted with acetic acid to form a polymer forms the base, the plasticizer is added to make it more flexible and adjustable, which is important so it can be properly fit. Too much plasticizer and the acetate is soft and picks up a lot of water making it unstable and speeding its surface degradation which is often seen as whitening as times go on. The lower plasticizer/harder acetate also takes and holds a better polish. There are currently two “Japanese” acetate manufacturers, one still manufactures in Japan, the other has moved to China but is still made to Japanese specifications. A bit more heat is necessary in adjusting Japanese acetate frames. There are other differences as well with regards to how/when the acetate is bent which turns into a long discussion, but which can give more stable results.

Other differences between Italian and Japanese acetates include imperfections, something which doesn’t effect the end product as they are usually thrown away, but from a manufacturers standpoint makes a huge difference…it is frustrating to see a particle or air bubble show itself during the final polishing stages, it happens with acetate from anywhere, but is less likely with Japanese made acetates.

Finally, the color pallet. This is a matter of taste. The Japanese do a wonderful job with deep rich subtle colors, the Italians do better with bright colors designed to fit the latest fashion trends.

The Japanese also perfected titanium soldering and welding. There are many different ways to solder/weld titanium. The most commonly used practice uses a super high temperature solder to form the intermetallic bond between the two titanium parts. It requires a huge amount of energy; we will run 800~1000amps through a hinge to achieve this bond while blanketing it with argon gas. When something goes wrong, results can be spectacular!

 

titanium soldering
Titanium Soldering

 

 

The Japanese also have tremendous titanium plating technology. Typically, to get good adhesion between plated metals or paint and titanium, a nickel under-plate is used, for those with nickel allergies this can cause problems. The Japanese nickel free plating/painting processes are unparalleled.

 

Made in Japan?

And now for the bad news. Not all frames that say “Made in Japan” are really made here, actually, only half. Raw material suppliers know how much is being sold, the number of frames made is tracked, the amount of raw material is about 50%.

 

eyewear made in japan

 

If you contact many manufacturers they will give you an option, 100% made in Japan, or made overseas, “finished in Japan” (ie stamped or assembled) – this option is usually 25% cheaper or more…we get phone calls to do a final adjustment/polish and print, they get “the Japan salute”…this is not unique to Japan – same goes for Italy, France, and other countries I am sure. There is nothing wrong with made in China or elsewhere, but it is misleading at best, dishonest, and ends up hurting the manufacturers here as it drags down market price and doesn’t allow for re-investment.

 

Steps in making acetate frames, the short version.

 

1. Design:
This is where the magic starts. Some draw by hand (one of our designers is a talented artist and does preliminary design by hand) and others use design software or CAD (my hand drawings look like a baby writing with a crayon for the first time, I use CAD).

 

 

Changes in the frame size and look upon bending must be taken into account. Programs are written (for CNC cutting) or patterns are made (for pantographs). And one of the most important steps is the decisions on color. We have boxes of color chips from various manufacturers and settling on 4 or 6 combinations takes a lot of deliberation.

 

2. Cutting and Thicknessing:
Acetate comes in many forms depending upon which company makes it and how it is made. Slabs can be anywhere from 1kg to 10kg (~2~22lbs) and are typically 4~8mm thick. These slabs are cut with either a band or circular saw then if necessary will be thicknessed in a special machine. It is here where proper gradient position must be decided as well as working around defects in the acetate (some makers have more than others). As acetate frames are manufactured using a subtractive process, 90% of the material can be removed during processing. Shrinkage can actually vary upon direction you cut the acetate from the slab (most don’t know this) and cause problems later.

 

3. Machining Front and Temple:
Fronts and temples are then shaped. This is now done with CNC machines, though smaller shops often will use “pantographs” (a machine which traces a template and cuts the material). Our fronts and temples are often thicknessed in 3 dimensions (you see little of this outside Japan), it makes for a better balanced, lighter, and more comfortable frame but adds to the complexity and production time.

 

4. Core Insertion:
Probably the most difficult step of the entire process. The old school method is to actually laminate acetate around the wire – very time consuming, we have a proprietary process where we can laminate 3 dimensional wires, it is rarely done now.The vast majority of frames take a temple core (with or without hinge) and heat it to high temperature (>300C), heat the acetate with special HF heaters, and place it in a mold/jig, press the temple and “shoot” (push in) the core using a piston. Acetate hardness, production method, color, humidity, and room temperature can all impact results, cores can bend, wander, curve, breach…this process is as much about feel as technology…very few shops in Japan insert their own cores – we are one of 4 that I know of.

 

5. Front Bending and Stabilization:
Fronts are bent using heat and a mold. This is where the bridge shape as well as frame curve is pressed in. A relatively simple process on the surface, however, if not done properly can lead to frame instability later. There is a Japanese process that does this earlier (before shaping) which can lead to increased stability, we use special heat treatment processes after bending to remove internal stress and improve stability (this is very rare).

 

 

6. Barrel Polishing:
Once the parts have been cut, they are rough finished by hand using files and scrapers. Hinges are capped (covered with resin as to not cause scratches or wear) and the parts are run through polishing barrels or tumblers. These horizontal barrels hold media made of either plastic, wood chips, or bamboo chips varying in size and shape. Polishing compound and/or oil is added and the parts will tumble for between 6 and 24 hours or longer. We typically run 3 or 4 grits. Conditions are varied to give the appropriate roundness. The frames will come out scratch free with a sheen (to get a true mirror finish, frames must be polished by hand later).

 

7. Hinge Attachment:
We attach the front hinges after polishing, they can also be attached before polishing and capped. Hinges are either heat sunk (a hinge with an anchor on the bottom is heated and pressed into a hole in the acetate to the appropriate depth) or riveted (pins are pushed through holes in the frame and the hinge on the back, the pins are then “headed”).

 

8. Temple/Front Cut:
In this step the back corners of the front, and the compound angle on the temples are cut so they fit seamlessly. On high quality frames the temple is ground flat to the front (if you feel bumps on the outside of the front it means the manufacturer cut corners by just hitting it with a polishing wheel.

 

 

9. Polish:
Great finishes take care and attention to detail. This is the most time consuming step of all – it actually can happen at various points in the process, sometimes before or in between tumbling steps. Polishing wheels of various materials and construction are used with different compounds or “grits”. Compounds which cut metals are used to flatten rivets with heavier fabrics and super fine compounds are used to get the final sheen. Too much pressure and you melt the plastic, too little and you don’t remove scratches. We have wheels specially made for us using various fabrics sewn in different manners to control scratch size and depth. Good polishing is more of an art than a science and can really impact how the frame retains its shine over time.

 

10. Print, Temple Bend:
After polishing, temples are printed. There are many different printing methods, pad and silkscreen are the most common, however, the printing can rub off over time. We typically use hot stamp (a metal die with the inverse of the printing is heated and pressed through foil into the acetate) or laser printing. Temple tips are then heated and bent in a special machine (or by hand).

 

11. Lens Insertion, Final Adjustment:
Frames are then heated and adjusted and lenses are cut and fit. Frames go over final inspection and are packaged up ready to go.

 

What is hand made?

The image of a craftsman creating a frame using only a coping saw, a file, and a few hand tools is romantic and honestly far from the truth. I do know one or two craftsmen who can do it skillfully, relatively quickly, and repeatedly, however, the vast majority of frames (99.999%+) are made using equipment of some sort or another.

 

 

Some argue that hand made frames are not CNC machined, I would disagree. The time to produce an acetate frame is measured in hours not minutes or seconds, the time a frame spends in CNC machines is maybe a couple of minutes. The rest of the time frames are manipulated and worked by hand. Tracers/Pantographs are guided by hand but honestly, take less experience, skill, and know-how to use than a CNC machine – I can teach a novice to use a pantograph in 15 minutes and they will get reasonable results, a good CNC operator takes significantly much more study and skill. At the end of the day, it is the amount of attention to detail that determines a frames quality.

 

Christopher Esposito

 

 

Creator, designer, craftsman, chemical engineer. A bit of a “Jack of All Trades” as it were. Born in a small town in Massachusetts, educated at Tufts University, he graduated with a degree in chemical engineering in 1992. Captivated by the Japanese culture he moved to Japan in 1994 for a 2 year stint as a research scientist. “Kidnapped” by the then company and his now wife that 2 years turned into more than 25. Christopher is the owner of E&E LTD and creates furniture and the eyewear brands Say-Oh and Ethnicity.

 

You can directly contact Chris