SuperLuminova Episode 5 – Performance, Application & Nomenclature

SuperLuminova Application & Nomenclature

This week we are all about SuperLuminova performance. Welcome to the fifth episode of our Swiss SuperLuminova series. Albert Zeller, the CEO of Luminova A.G., and I are going into the details of how Superlumiova works and how it should be applied to watches for the best results.

To get the most out of this episode, it is best to ensure you have watched all those that have come before. They all contain valuable information about Superluminova but also key information to make this episode much more understandable. Just in case, you can catch up on episode one that introduced us to SuperLuminova, what it really is and how dangerous it is or is not.  Episode two is all about emission colors and daylight colors, and the amazing research keeps Superluminova at the forefront of their industry.

Episode 3 goes into the fundamentals and looks at how the electrons move up and down in energy as they absorb and then release each photon of light.  Do not worry, we keep it simple, so hopefully, everyone can understand how it works.  Episode 4 looks at the trade-off between all the daylight colors and luminous performance.   

My name is Stephen Mansfield. I am one of the co-founders of SNGLRTY, and I am delighted to have the opportunity to discuss this amazing luminous material with Albert Zeller. 

Today we are going to look at the practical aspects of applying Swiss Superluminova to a watch. This takes us into the world of binders, and we revisit how the daylight color impacts the luminous performance.  Plus a little bit of history around the naming convention of some of the most popular luminous colors. 

Steve:

We have been talking about the luminova pigment in our last discussion. You have told us that the applied pigment concentration is critical to ensure we get the best performance from the SuperLuminova.

You mentioned that binders are important in the application process. These are the glues that we use to transform the powder, the SuperLuminova powder delivered to the customer, and transform it into the paint applied to the watch face. Are the binders and the mixing of these solutions applied something you at Luminova A.G. control, or is this something that the dial maker, the watchmaker, controls?

Albert:

We produce the binder and the pigment separately. The reason is that it does not make sense to use the same binder for all applications. So we also have many different binder systems, which we also make in-house. There are around 300 different types of binders. For example, it makes sense to use a solvent-based binder for the watch hands.

Whereas if you use a solvent-based binder on the exterior of a watch, that would be a terrible idea. If some acetone or anti-mosquito spray then came in contact with the luminous deposit, it would dissolve once again and fall off the watch. 

In this scenario, it would be advisable to use a UV curing binder or a two-component binder.  In the end, every luminizing company or dial or hand manufacturer needs to make these decisions in collaboration with their customer to ensure the best physical and luminous performance.

Each manufacturer has its own binder and mixture process that they prefer to use. There are also different mixtures of binders depending on the shape of a hand. For example, the mixture may need to be a little more liquid; this will reduce the mixture’s pigment concentration. Whereas in other applications, it makes sense to reduce the concentration of the binder. If you are looking to set dots on the dial, they need a certain volume, and to avoid shrinking, you need to maximize the solid applied and so the binder is reduced.  This increases the concentration of SuperLuminova in the mixture.

Steve:

Albert, we can see that C1 is the traditional white. Daniel and I noticed when we were doing some dials for our watches at SNGLRTY that there is a new option called TC1. What is the difference between these two?

Albert:

Actually, I have to explain a little bit about the origin of TC1. What TC1 stands for is “Top C1,” which is the reason for this reference. C1 is a very pure white-colored Luminova. As mentioned in episode four, a large amount of colorant needs to be introduced into the pigment for a pure white. 

When we moved from Standard Grade to Grade A, we thought about how this C1 should be configured and, in particular, whether so much white colorant needed to be introduced into the final pigment. Is it essential to put so much whitening pigment into that mixture, or is a little bit off-white acceptable?

So that is why TC1 was created. It is just a little less white than C1 with a better base pigment, and as you can see from the chart below, TC1 is double the performance of C1. This is a good example of how a better base pigment and less coloring impacts performance. If you choose the X1 quality, that is a better base pigment. You can choose from 10 different grades of white that we offer.  They start with TC1 body-color and then incrementally, from white 10 to white 90, closer to C3.

The luminous performance also improves the closer to C3 we get. I doubt anyone would see a difference in the daytime color, but the luminous performance can significantly improve. I think, from C1 to white 10, the luminous performance improves more than 20%, so it makes sense to not just specify white but to investigate the alternatives.

Steve:

We have been referring to all these “C” numbers C1, C3, C5 in all these discussions. Perhaps, we should just take a little break here, Albert, for you to explain to us where these references come from? I think that would help a lot of people.

Albert:

This comes from the history of luminous applications to watches. When the tritium luminous pigments were the standard for luminous pigments application, there were specific colors defined. White was C1, C3 was the natural color, then C5, which is a little greenish, C7 is a little bluish, then C9, and so on. So this refers to color one, three, four, five, and so on, but over the years, as you know, designers have become more creative.

When we changed from tritium to SuperLuminova pigments, people still wanted to look the same as they did in the old days, so we also had to reintroduce that nomenclature today. We usually work with Pantone colors because all designers have sample cards. You can also choose from a bit wider than just C1 to C9. From the chart, we can see that C3 is the best-performing pigment, this is pure luminova pigment, so it is always the best-performing pigment. C3 in standard quality is good, but C3 in X1 quality has twice the luminous performance.

Steve:

Okay, so I just want to make sure I have got this clear in my head. If we take the C3 pigment, that is the best-performing pigment and is pure SuperLuminova, a yellowish off-white color. If we add a colorant to C3 pigment that changes the physical daytime color of the Luminova, the luminous performance is reduced.

The reduction in performance comes from three effects. First, the colorant dilutes the number of available emission centers for a fixed volume of Luminova. This is one way the addition of the colorant degrades the quality of the luminescence. A second effect is that the colorant interferes with the incident light that charges the light batteries. The colorant that is added can absorb the charging light. Rather than charging the light battery, many photons of light are absorbed by the colorant rather than the emission center.

Finally, when an emission center releases the photon, there is a chance that the photon of light does not actually emit past the colorant. It is absorbed by that colorant. In summary, the colorant reduces the emission centers’ density, and then the colorant itself absorbs the charging photons, plus it absorbs the emitted photons. Hence, three key mechanisms reduce the quality of colored SuperLuminova. Am I correct?

Albert:

You’re completely right.

Steve:

Excellent I’m glad I understood it.

Albert:

Actually, it is not that bad, but then people always expect that black SuperLuminova has the same performance as a C3, and it does not work like that.  If you have a light bulb in your office, it is nice and bright, a beautiful white bulb. But if you paint it black and switch on the light again, it can emit white in the center, but very little light will emit past the black paint. 

Thank you very much, Albert. That is the end of episode five of our SuperLuminova series.

Episode 6

Next time we are going on to look at Lumicast, which is I think if you like bright SuperLuminova on your watch, it will be a revelation for you. We’ve got a quick summary of what’s going on as well over the whole of the last five episodes, too, so do join us.

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