Marcus Hanke[PuristSPro Moderator]
11519
The big SuperLuminova luminance comparison test
Jun 14, 2012,15:08 PM
Let's test the performance of various SuperLuminova variants
by Marcus Hanke
Especially
on sports watches, luminance is a vital design element: even when we
are not diving in the depths of eternal submarine darkness
Some
six years ago, I wanted to compare the luminosity of the non-radioactive
SuperLuminova with that of the traditional tritium-activated phosphorus
and conducted a small test, with the Ulysse Nardin Marine Diver being
the the SuperLuminova candidate, and the classic IWC GST Aquatimer with
its infamous tritium-SL-combination dial representing the other
category. The outcome of the test was quite interesting:
ulyssenardin.watchprosite.com
During the following years, it has become a design trend to use
not only the “classic”, greenish SuperLuminova as luminous substance on
hour markers and hands, but to tint that in different colours. This
permits a larger freedom in combining colours on watches and therefore
offers a wider spectre of watch designs. Coloured SL is produced rather
easily, since the the original state of SL is that of a fine granulate
or powder, that is bound by liquid substance to be applied on dials and
hands. Any colour pigments can be added to the SL granulate in order to
achieve the desired effect. This can go so far as to add black pigments
that result in a black marker or hand that glows in the darkness.
Nemoto, the inventor company of SuperLuminova, and its main license
partner in Switzerland, Tritec, offer a wide array of colours.
Currently, the use of tinted SL became popular to simulate the
appearance of old and yellowed phosphor on vintage timepieces.
Luminova colour charts by Nemoto (left) and Tritec (right)
However,
this freedom of design comes at a price: the colour pigments reduce the
intensity and duration of the SL’s phosphorescence. In the case of
black-tinted SuperLuminova this even leads to nearly complete
ineffectiveness, which raises the question why someone would spend the
money for non-luminescent luminous mass?
Another development is
that of a bright white SuperLuminova. The well-known SL that is used
since 1993 is of a light green colour, with its current formula wearing
the technical designation C3. Despite its high efficiency, the greenish
tint is not popular among watch designers, since it is not a perfect
contrast with most black watches, or blue dials. Therefore, the
development of a bright white pigment, dubbed C1, was a real progress,
and currently a majority of sports watches is equipped with this
material. However, already the data sheets suggest a reduced
phosphorescence intensity of C1, compared with that of C3.
Another
aspect worth to be pointed out is that the colour pigments added to the
SL only marginally influences the actual glowing colour. Basically, all
kinds of SL are glowing in pale green, regardless of their appearance
in daylight. There is only a very decent colour tint when such pigments
were added to achieve, say, a bright blue or red SuperLuminova marker.
My
new test should now reflect these new design trends, by comparing a
watch with classic greenish C3 SL with others having white C1 and
brightly coloured SL. Of course it would be perfect to have three
watches of the same brand and line, with only the luminous material
being the difference. However, my choice is limited to those watches I
have in my possession, so I have to combine different brands.
Obvious
candidate for the C3 fraction, and unbeaten “master of glow” in my
collection since more than ten years is still the Marine Diver by Ulysse
Nardin. Up to now, I had no watch that could really compete with the
intensity and duration of its luminescence.
Ulysse Nardin Marine Diver
In
this context it is necessary to point out that, despite the use of
identical SuperLuminova materials, there are many other factors
influencing its efficiency: the purity of the granulate, its sealing
against humidity, the thickness of application, the type and colour of
its base, and some others. Consequently, it is not only possible, but
rather probable to find two different watches with the same
SuperLuminova equipment to perform very different in the luminescence
category.
C3 SuperLuminova on the Marine Diver
That
Ulysse Nardin lent me a very new and rubberised special model of the
Marine Diver, the “Red Sea”, was a fortunate opportunity, since it has
the same hand and hour marker design as my older watch, but sports an
all-over bright red SL equipment, offering a perfect comparison
candidate.
Ulysse Nardin Marine Diver "Red Sea" with red tinted SuperLuminova
Finally, my nice Tissot PRC 100 chronograph with its bright white C1 SuperLuminova completes the trio.
Tissot PRC 100 with white SuperLuminova C1
Since I did not yet have night shots of two
other “retro-design” sports watches, I added these as well: the
well-known Legend Diver by Longines, and the large Breitling SuperOcean
Heritage, both equipped with C3 on hands and markers. These two
eventually allowed another interesting conclusion.
Longines Legend Diver, SuperLuminova C3
Breitling SuperOcean Heritage with SuperLuminova C3
Testing Procedure:For
a good “charge” of the luminous elements, I placed the watches in very
bright sunlight, since the strontium aluminate in SuperLuminova is said
to be best charged by the visible spectrum of daylight. I considered two
hours to be enough. Then I brought the watches into a window-less room
in my house’s basement, where I had already prepared my camera on a
tripod.
I had planned to keep the exposure values preset on the
camera the same, throughout the whole series. This should cover about
six hours, with pictures being made shortly after the daylight exposure,
an hour afterwards, a further two hours later, and finally after six
hours. The automatic white-balance on the camera was changed to a
daylight preset, since otherwise the colour of the glow would change in
every picture.
Since my 60mm macro lens on a camera with APS-C
sensor corresponds to roughly 100mm on a full format sensor camera, the
working distance between the watches and the camera was rather large,
about forty centimeters. Consequently, the intensity of light recorded
by the sensor was much lower than it had been in my experiment conducted
six years ago, due to the much larger distance. Thus it does not make
sense to compare the new test pictures with those in my earlier article.
To
my shame I have to admit not having read my own article before
conducting my new test. Otherwise I would have been warned about the
massive drop of glow intensity already within the first hour, and used a
camera setting that maximises the light recording. Instead, I repeated
the same mistake of six years ago, and realized that my initial camera
setting, that brought the most satisfactory pictures of the “fully
charged” watches, resulted in near-complete darkness on the pics only an
hour later.
The first shot looked nice ...
... only to lead to unacceptable results only an hour later.
As a matter of fact, SuperLuminova’s afterglow luminance is reduced to about 6% of its original value within 60 minutes.
(c) Nemoto
Therefore,
I decided to recharge the watches with the light of two halogen working
lights for about twenty minutes and to repeat the initial shot, showing
the watches at full charge, but with the same camera settings used for
the shots at 1, 3 and 6 hours. This explains the display of the wrong
time on the first picture.
Test results:I
think the pictures to be rather self-explanatory. Please keep in mind
that the depiction of the glowing watches strongly depends on your
individual monitor settings, especially the gamma value. While some
might not see any luminescence on the later pictures, others might see
the markers and hands much more clearly. It is the relative luminescence
intensity, compared within the watches, that counts. The text in the
pictures will also help, since its colour is picked from the “Red Sea’s”
glow in the first picture, and kept the same throughout the whole
series. A dark background on the monitor would be perfect, but our forum
software only offers a bright white which kind of outshines the faint
glow of the watches in the pictures.
The
most apparent test result is that neither the coloured SuperLuminova,
nor the bright white C1 SL are matching the efficiency of the older C3
SL on the standard Marine Diver. Especially the colour tinted SL of the
“Red Sea”, while equally lavishly used on hands and markers, is just
barely visible after only 1.25 hours of darkness, the later pictures
(3.25 and 6 hours) only show darkness at its position (bright monitor
setting will show a very faint impression of the watch being there,
though). The white C1 SuperLuminova of the Tissot is only marginally
better.
The
conclusion is that if you search a watch with optimum night visibility,
make sure to choose a watch with the greenish C3 SuperLuminova, instead
of the more fashionable white or colour-tinted substances.
What about tritium?However,
I have to add a certain reservation to this statement: While
SuperLuminova is the most frequently used luminescent agent on watches,
it is not the only one. A highly interesting alternative is the
“Permanent Light Technology (PLT)”, developed by the Swiss manufacturer
MB microtec AG. The system consists of tiny crystal glass tubes, coated
with phosphorescent zinc sulfide on the inner side, and filled with pure
tritium in gaseous state. Unlike the older, now forbidden
phosphorus-tritium granulate used for decades on watch dials and hands,
Microtec’s system assures that no radioactivity is leaving the glass
tubes, and also the glowing efficiency of the luminous substance is much
higher and more stable, mostly due to the high pressure of the gas in
the tubes. These attributes made the PLT a perfect supplier for the
watches of the US military, with the watches being produced under the
brand name Traser. Tritium gas tubes are available in different colours,
too, but like the coloured Luminova material, these are nowhere as
bright as the pure, greenish tubes.
However, PLT is suffering
from two disadvantages: the first is a limitation for the watch design,
since the small tritium tubes (with only 0.5mm in diameter, in lengths
from 1.3 to 6.6mm) that can be used in wristwatches are produced in
cylindrical shape only and therefore watch designers have to tweak their
drafts considerably, to accommodate the tubes in their numerical
markers or classically shaped hands, for example.
The second
limitation lies in the tritium’s nature as radioactive substance. By
constantly emitting energy, tritium transforms into helium. After 12.3.
years, 50% of the tritium has made this transition and ceased to be an
activator for the luminous substance. After another 12.3. years, a
further 25% of the original tritium amount is inactive. Consequently,
the luminescence intensity of tritium tubes is reduced by roughly 10%
each year. Since the tubes are highly standardized, most watch
manufacturers using them guarantee a steady supply of fresh tubes that
can be exchanged for the old ones.
Most Traser watches are
equipped with quartz movements, but there is a brand offering
interesting mechanical watches with tritium tubes, Ball. Unfortunately,
Ball is distributed neither in Germany nor in Austria; I would have
liked to get my hands on one for a test, but this will have to wait.
According
to MB microtec, the tritium tubes are glowing considerably brighter
than SuperLuminova already after a minute of darkness, with no
measurable intensity reduction, aside the natural deterioration due to
the radioactive material’s half time.
And the other two watches? Finally,
a few words should be dedicated to the last two watches of my small
test: the Longines and the Breitling. Both are equipped with the same C3
SuperLuminova, and yet there is a distinct difference in the intensity
of their glow already after an hour of darkness. the main reason for
this presumably lies in the care of the C3’s application: The Breitling
has small luminous dots near the hourmarkers, all of them being domed
rather high placed on bases made from white lacquer. The latter
perfectly enhances the glow.
The Legend Diver, on the other hand, has
thinner, less evenly shaped strips of SL applied to the dial. While they
also have a white base, this seems to be less smooth and shiny than
that of the Breitling’s markers.
This
makes the difference between the two watches. Apparently, also the
hands are differently treated with SL, since the Superocean’s hands are a
lot brighter as well.
And in another six years? Who knows which
enlightenment technology will come next? LEDs powered by a
micro-generator charged by the winding rotor? We’ll see, in my next test
- 2018.
Finally, let me quote my own article from 2006: “If you
have succeeded in reading all the way down until here, you will agree
with me how fascinating it is that someone can spend so many words on
such a minuscule detail. Oh watch enthusiasts - aren't they crazy?”
Copyright June 2012 - Marcus Hanke & PuristSPro.com - all rights reserved
PuristSPro Homepage | ThePuristS Homepage
Comments, suggestions, and corrections to this article are welcome.
This message has been edited by Marcus Hanke on 2012-06-14 15:08:44 This message has been edited by AndrewD on 2012-06-21 19:26:34