Why is my Pulsar Sapphire glass white when viewed sideways?

[Absolute-Poet]

Now firstly let me apologize if this subject has been covered before, but I cant find any posts on it. If so, just point me in the right direction and I'll blitz this post.

The subject of the real colour of a sapphire crystal would seem to be a bit of a controversial subject to me, for 3 reasons:

1. Sapphires are naturally blue in colour, so why are the ones used in LED watches dark red like a ruby?

2. Watches such as Rolex use sapphire crystal glass too, however, this is completely transparent, which I believe is man made in this way for this purpose.

3. The colour of the crystal on my 5503 touch command is red of course, BUT, if you look at it from the side clearly is transparent! This would lead me to believe that the crystal must be similar to those used in Rolex, Omega, etc. but must have some kind of red mask or filter behind it, correct?

Now, I'd be very interested to hear some feedback from some of you crystal grinding, extracting analysts out there! LOL

Go for it, whats the REAL story here? Thanks guys!

[rewolf]

http://en.wikipedia.org/wiki/Sapphire:
Sapphire refers to gem varieties of the mineral corundum, an aluminium oxide (Al2O3), when it is a color other than red, in which case the gem would instead be a ruby. Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple, orange, or greenish color. Pink-orange corundum are also sapphires, but are instead called padparadscha.

Watch crystals are made of synthetic sapphire and thus can be made in any desired colour. For LED watches, red is best because the LEDs emit red light; green crystals for green LEDs etc.

I don't know anything about the 5503's crystal, but it is not uncommon to use a clear crystal with only a thin filter coating.

[Absolute-Poet]

Thanks Rewolf, I'd imagine that must be the case then. Perhaps its got some kind of red film inside the watch under the clear crystal.

Either that or Ive got a non-genuine crystal in it perhaps? Looks kind of too perfect considering the watch is 32 years old anyway!

[bruce wegmann]

You're seeing what you're seeing because you are looking through the clear upper layer of the crystal. Pure aluminum oxide is colorless; small percentages of other metals [replacing aluminum in the crystalline lattice] produce a wide range of colors, chromium gives sapphire a characteristic red hue. Laser ruby has about .5% chromium content; gem pidgeon-blood ruby about ten times that. The light-transmission characteristics of ruby are a good match to the output wavelength of the LEDs, making it an efficient filter and contrast enhancer. Only the P1 used a solid synthetic ruby timescreen; all other models that had sapphire crystals used a multi-ply sandwich of clear sapphire, a binder, red filter, and glass. Only contact with diamond, another sapphire surface, or crystalline silicon carbide can scratch these crystals, so it is not such a surprise that your watch still looks good after a third of a century; that was, after all, the design goal. Unfortunately, it solved the scratching problem, only to create another...delamination. Years of exposure to UV light and daily thermal cycling can eventually break down the adhesive joining the layers; this shows up as silvery-colored areas, usually around the periphery of the crystal, particularly at the corners [the TC repair department probably never saw one do that, unless there was a defect in the manufacturing; it took many more years than the company lived, for this to become a serious problem]. Use of heat or solvents to remove these crystals from a case also tends to delaminate them, and there is no easy fix. Time Computer used this type of timescreen on several models, including the P4 Classic, Executive [rare], PRM, Dress, Ladies' Touch-Command, and Calculators. So far as is known, neither Hamilton nor Omega usedthis technology on their LED watches.

[Absolute-Poet]

Thanks Bruce, I really enjoyed reading that! I dont think anybody could havent given me a more accurate and interesting answer.

I find it fascinating how these things were put together using technology that is now over 3 decades old to us!

What I have noticed on closer observation are these silvery marks you mention, although very very faint. Also, there appear to be very slight gaps between the crystal and the casing on all 4 corners as if the rounding off was not perfectly matched to the case seating dimensions.

My guess is the crystal has been removed and ground down at some point, or its like that for expansion and contraction purposes so the crystal doesnt get craked through the different temperature ranges it will endure in its lifetime. Im sure you will know the answer to that one!

Interesting stuff, thanks again for your input!

[bucko170]

all other models that had sapphire crystals used a multi-ply sandwich of clear sapphire, a binder, red filter, and glass.

Very interesting, would you have a photo that shows the different layers?

[Absolute-Poet]

Hey Buck, from Robin Hood land I see, me too! However, Im living in Spain now and havent been back for years!

Photo of the layers? Lol Nice one! I You were hoping for a good wind up I guess, hehe! I might be new but Im from Notts too!

[bucko170]

You were hoping for a good wind up I guess

Err actually no, you said....

if you look at it from the side clearly is transparent

I thought that if you could detect it with the naked eye you might be able to shine a light through and capture a side view of the different layers on photograph - I've not seen a sapphire crystal before and it would be interesting to see one in close up detail.

Im from Notts too

Small world, where abouts in Notts did you live before you made your escape to the sun?

[Absolute-Poet]

Lol! Sorry Buck, thought it was one of the lads wanting a laugh on a newbie! I was in West Bridgeford for a while, then Plumtree where my grandfather had a plastics factory... Surfleets plastics PLC.

Im afraid I dont have the equipment to be able to get an accurate close up enough shot of the crystal, sorry. I would imagine it would require removing from the watch to see it clearly anyway. But basically its got some kind of red layer embedded in it down below beneath the clear part, clever stuff!

Do have LED's yourself? Apparently theyre all made slightly differently as explained by Bruce, but the P1 sounds like the mother of them all!

[bucko170]

Do have LED's yourself?

Loads: but no sapphire crystal

[charger105]

Thanks for the interesting post Bruce.
When you said:

all other models that had sapphire crystals used a multi-ply sandwich of clear sapphire, a binder, red filter, and glass

I thought you meant this included P2 and P3 too, but after checking I see these are spec'd as 'mineralite glass'. Is this just solid red glass ? What does mineralite mean ? Is the synthetic saphire more scratch resistant than the mineralite galss ?



Rgds,
Andrew.

[bruce wegmann]

To my knowledge, no P2 or P3 ever left the Lancaster facility with a sapphire crystal. True, one meant for a Classic or PRM would fit and work as a replacement in a pinch [as they are dimensionally identical], but all indications are they first appeared on the P4 models [the Big Time is universally found with a mineralite glass crystal, however]. Mineralite is a trade name for a particularly hard and tough high-silica glass. It has about the same hardness as quartz [7 on the Mohs scale; sapphire is 9, diamond 10]. In real-world terms, sapphire is about 40 times as hard [and scratch-resistant] than glass. I am not enough of a chemist to tell you what metal oxide is added to produce the deep red color; you'd have to go to Corning [who probably supplied all the Pulsar glass] to find that out. The laminated crystals were a clever attempt to overcome the scratching and chipping problems inherent in glass; it was very successful up to the point where failure of the adhesives posed a new one.

[retroleds]

Here is a picture of the Sapphire layer, separated from the paper thin plastic film that is on the back. The entire package is just a hair over 1 mm....about half the thickness of a standard mineral glass screen. The logos are painted onto the back side of the clear layer, not baked on like a glass screen, so trying to separate the layers to clean them in hopes of reglueing a film to them is generally a failure or at least causes some damage to the logo. I'm hoping to experiment with filling the de-laminated area without removing the crystal, using the vacuum setup I have been using to debubble my epoxy lately, Basically I want to see if I can induce the air to come out and some silicone to fill the gap, by flooding the inside of the case with the silicone and leaving it in the vacuum chamber at 20-25 bar for several hours. Worth a try...De-laminated ones look terrible. And Bruce is right that removing the crystals just causes more delaminating.

[bucko170]

The logos are painted onto the back side of the clear layer

And so that is why they are described as having a floating logo

[Absolute-Poet]

Thats very interesting stuff guys, 2 days ago I knew nothing about these processes.... now when Im in a pub and somebody asks me about my watch Ive got some serious teckie talk I can spin them off! Being an electronics engineer by trade I know how all the electronics work, but the crystal composition and manufacturing process is new to me and love learning about it.

So what do you reckon to these very slight gaps between the crystal edges and the casing around all 4 corners of my 5503? Its as if the rounding off was not perfectly matched to the case seating dimensions.

From what youre saying I guess the crystal cant have been removed and ground down as surely its composition is too hard in comparison to mineralite to do so? Also, if it had been popped out and played with it would surely have de-laminated as retroleds says. And theres no signs of any tampering, marks behind the crystal, etc. Its a crystal clear and clean screen. Maybe indiscrepencies between the glass and the case manufacturer? Or do any of you guys know the reason for this? Ive noticed other models with mineralite glass dont have any such gaps.... Mmmm, food for thought!

[retroleds]

Ive noticed other models with mineralite glass dont have any such gaps.... Mmmm, food for thought!

Well, there is a range of tolerances in anything, so that is surely part of it. And the red crystals were setted with a black epoxy, which makes any gap fairly inobtrusive; whereas, the clear sapphire would seem to optically float away from the case no matter what color glue you used. And being as how the sapphire is so thin, it might have been better for it to have some room for "give" in the case of some blunt trauma, then to have an absolute rigid fit. I'm sure they have a certain amount of give...
Oh hey, everyone is asleep here but me so I've gone out to the barn where I have my machine shop setup - put the crystal curved side up on the granite surface plate, put the indicator on it while holding steady - one can easily flex that curved crystal 3-4 thousandths with approx. 5-10 kg of thumb pressure. in the center.

[Absolute-Poet]

Hey thats cool, didnt realize that stuff had any flexibility in it at all! Thanks for trying it out, I hope its not my fault you were up at that time! LOL

I wont try applying any pressure to my 5503, looks such a fragile little thing! I once saw a 5503 on Ebay with a bubble beneath the glass, went for 300 bucks! I guess that one had been subjected to UV rays, temperature differences, and maybe pressure or knocks for that to happen.

Chances are mine will only come out at night, so hopefully no nasty UV's are going to cook my crystal!

Righty, my turn to get some sleep this side of the world! Goodnight USA, over and out.

[retroleds]

Hey thats cool, didnt realize that stuff had any flexibility in it at all! Thanks for trying it out, I hope its not my fault you were up at that time! LOL

Hey, the little details and quirky factoids are what make this interesting, at least for me. No lost sleep...it was early morning here...I was trying to let 5 sleeping women stay that way, so I was creeping around quietly. As a backup plan I already had a batch of pancake batter made, sausage thawed out and a pot of coffee brewing(tea drinker myself, usually). After 3 wives and 26+ years of married life, I know the path to a woman's heart runs right through their stomach. Especially if they are PMS'ing.

[Absolute-Poet]

You sound very wise in that dept. Retro! Lol I dont seem to get it right with women, hence never taken the plunge! Some have tried but its been a "jump on bike job" and ride off into the sunset! Lol

Sounds like you've got it sussed! I might have to try that pancake thing!

Do you find that the ladies dont understand what all the fuss is about when it comes to our LED's?

Still, we've gotta have our little piece of incomprehensible fun right?

[retroleds]

Do you find that the ladies dont understand what all the fuss is about when it comes to our LED's?

Actually, the wife is more of an LED wearer and collector than me! I'm not a big wearer of jewelry but I like the technology and fixing the stuff up for others who get a serious kick out of it. The wife has an LED collection many men would envy - most of the Lady Pulsars in both S.S. and gold filled, a few pendant(necklace) styles, some touch-command tyes,various curved and bangle styles and a green Men's Dress Pulsar glass and module put into a gold-filled case, with a black leather band. Her eyes vary between green and blue depending on the light.... and considering she is fully employed with a Master's Degree+, AND (the deal maker) very amorous. How could I say no?

Hey, the marriage thing isn't for everyone - as long as you are content, and get your physical and emotional needs filled, you are in good shape I'm thinking.

[Absolute-Poet]

Think you've got it absolutely spot on there! Good man, 3rd time lucky as they say! Lol

Hey, that certainly is an LED collection to envy! I like the sound of the green crystal put in the GF case, funny as I had that idea in mind for some time in the future, not too keen on the SS case it comes in by default. Tried to find a greenie as my first Pulsar, but boy they were going for 1500 bucks plus! Very special though!

Well, its not that I flatly refuse to get married, I guess the right girl has never crossed my path! But hey, you never, know... maybe your wife has a younger sister that's into LED's and motorbikes!? LOL

Im starting to get bored of Spain now anyway! Lol!