***Anti-reflective coating (AR)
A number of subscribers were curious to find out more about
'reflectiveness' of watch crystals and anti-reflective coating
solutions. Before we go any further: I am not an expert in the field of
optics. Like yourself, I am just trying to figure out what may work and
what could be improved. In other words, in the same boat as any other
watch brand and watch enthusiast.
The core of the problem lies in the geometry of modern sapphire watch
crystals: flat glasses are less reflective than domed ones, and double
domed are double the trouble.
Traditionally, in the early days of wristwatches, watch glasses were
just that - made of polished glass. Its main and only function was to
protect the dial and fragile hands - and clarity, low distortion and
reflectiveness were secondary properties. Also the glasses were much
thinner and watches were of smaller diameter. But in just a decade or
so later a novelty kicked in: covers which were made of natural rubber -
known in the trade as kautschuk. A watchmaker would simply buy 'cured'
see-through sheets and cut and mold his own covers. By the 1940’s, a
synthetic polymer methyl methacrylate (better known under the commercial
name plexi glass) kicked into fashion: it was cheap to produce. It
was almost unbreakable, it never shattered, and was incredibly
glare-free. However, one incredible property of plexi glass was it was a
perfect self-sealant to stainless steel cases, and it was thanks to
humble plexi glass that waterproof watches were really possible. An
example of 1950’s plexi glass development – probably the two best known
are Rolex Submariner 5513 and Omega Speedmaster (yes, hesalite is just a
fancy word for plastic).
Plastic only had one negative property which is it is very easy to
scratch. By the early 1970's plastic covers were, once again, out of
fashion, being rapidly replaced by modern domed and double dome mineral
crystals and later sapphire crystals - a modern attempt to offer
customers that elusive 'scratch resistance' experience.
So we got back to where we started: having to, once again, deal with distortion, glare and reflection.
There is no such thing as 'spray on' anti-reflective coating. The
applying process itself takes a few hours, as sapphire passes through a
number of cleaning/coating/curing steps.
The photo on the top shows non-coated crystal on the left and AR coated
on the right, both subjected to the same light source. The difference is
day and night! The trick is to have just the right amount of coating
which will not 'tint' the dial (turning the black to purple or blue)
while having the coating layer of sufficient thickness which will
'stick' to perfectly polished crystal for as long as possible.
Based on my experience, Breitling and IWC are trying hard to solve
this problem, while Omega has reached a stage where AR coating is as
close to perfect as we can expect with available technology. The new
Seamaster crystals look just stunning, offering a glare-free view of
dial and hands.
In our case, finding the best AR solution means sending our crystals to a
few different coating specialists, then comparing the results. Yet
another R&D project for the smallest watch brand in the world.
Costs? USD$175 per batch of 100 - meaning $175 to coat just one - or 100
crystals.
Exciting project for sure. Will keep you informed.
In case you missed our earlier announcement for Mark 1 orders
40mm automatic), click on the link below. And in case you have put your
name down on the waiting list but have not received your confirmation
email and your assigned number - please contact us again.
Mark 1 - Taking Orders Now
