TiGlow Encapsulation

I'd like to post this as a reference for those who might be interested in encapsulation/potting of the TiGlow glowrings which were offered by B@rt in the B/S/T forum here.

My first one lasted less than a month under mostly keychain carry before I managed to pop the vial. The holes leave a significant portion of the glass vial exposed (although recessed) and, IMO, it's only a matter of time (on a keychain at least) before something pokes its way in there. The vials themselves are quite expensive, so (IMO) are worth the time and effort to protect further. As far as I can tell, the easiest way to encapsulate the vial is to start with everything disassembled (I'm having B@rt ship my remaining TiGlows "unpotted"). It did not appear possible to fill each hole individually without leakage (which would likely make quite a mess of your TiGlow). However, the creative might try this approach anyway. It just might work with Norland 61 if each hole is first sealed by partially filling, then curing (maybe while rotating to keep the adhesive from leaking out onto the case), and finally, going back to complete the fill. Otherwise, a more viscous adhesive might not be so prone to leakage… just some ideas.

Anyway, what follows is my procedure for encapsulation of a TiGlow.

Materials:

Norland 61 optical adhesive (NOA 61) (available here)
Gloves (preferably nitrile)
Isopropanol (aka, rubbing alcohol) – good for precleaning and cleaning up uncured adhesive
Dremel 453 Chainsaw Sharpening Stone (4mm)
Small syringe with needle (requires ~0.5cc of NOA 61)
~2 inches of LS/15 silicone tubing (Masterflex 96410-15, available here or PM me and I might be able to help you out). Other silicone tubing would likely work, but this is what I used and what I also consider to be ideal for the task.
Razor blade


Here's the stuff...

• Bored out titanium case with the Dremel grinding stone, just enough for a slightly loose fit which will allow the NOA 61 to flow past when inserting. I used a fairly low speed drill for this, running at 100-200 rpm or so, 5 minutes on and off until I was happy with the fit.
• Cleaned tritium vial, titanium case and silicone tube with soap and water followed by rinsing with isopropanol.
• Dried everything thoroughly
• Inserted titanium case into tube (it will slide in under firm pressure)
• Cut away excess tubing
• Inserted neoprene spacer, positioned flat, at bottom of case. In hindsight, I would probably leave this out since I believe this was responsible for releasing some air as it came into contact with the base of the vial (which had trapped an air bubble upon insertion). It did not appear to be necessary for maintaining proper position within the case once it was filled with NOA 61.
• Filled syringe with about 1cc of NOA 61 (requires 0.5 cc) and removed bubbles
  
  

• Carefully filled case from the bottom with NOA 61 (needle positioned at bottom)
• *Applied drop of NOA 61 to end of vial* (I tried this but don't think I used enough since I still trapped a bubble, but good wetting prior to insertion should help prevent air from being trapped at the vial's base)
• Slowly inserted the vial (wetted end first), being careful not to push it in too far (not really possible with spacer).
  
• Mounted in a vertical position
• Placed in direct sunlight to cure (weather: occasional clouds, UV index of 8 – i.e., summer sun) for 2 hours within the silicone tube, rotating 90° every 15 minutes (earlier experiments indicated full cure through this tubing within one hour in direct sunlight)
  
• Removed from silicone tube (carefully sliced lengthwise with razor, but it may be possible to simply push the case out – just make sure its fully cured, or the adhesive surfaces may smear)
• Placed in sun on top of some Al-foil for 1 hour for good measure (rotated 90° every 15 minutes)
• Post cure for 12 hours at 50°C (when mounting trits, I found this appeared to increase the hardness of the adhesive a bit – this is also the recommended procedure to achieve optimal bonding with glass)

…and that's it. A few tiny bubbles and minor cosmetic defects (barely noticable unless scrutinized), but thankfully no mess on the outer titanium case! The Norland 61 is so transparent that you'll forget its even there.

My new TiGlow has now lasted over one month on my keychain with no evidence of wear on the adhesive (which I worried could create a haze which would adversely affect light output). After a few years, it's certainly possible that abrasive wear could damage the adhesive so it won't look so pretty and won't transmit light as well. Polishing might be an option at that point, but either way I still feel the tradeoffs are well worth my piece of mind. This thing is NEVER going to break (I hope).

A nice thing about the silicone tubing I decided to use was the thick walls and small ID which appeared to apply significant pressure on each of the holes in the case. As can be seen in the picture below, I believe that this helped to recess the adhesive at these locations, which should ultimately help to limit damage from abrasive wear.

Sorry about the funky formatting (my pics are all over the place on my monitor) but I didn't feel like trying to fix it. Enjoy your TiGlow!

btw - It looks very nice paired with another piece of bead blasted Ti...

Wow! Very nice step by step and great pics! :twothumbs:

I will have to try it myself once I find some time... :candle:

Thanks for the writeup, i got 2 coming from B@Rt.

Is this something your willing to do for others? i'm not very good and making my projects neat and appealing to the eye.

Excellent writeup AvidHiker!

I've asked b@rt to send all 6 of my TiGlow's unsealed so I can encapsulate them this way :thumbsup:

This looks like an excellent idea, I was just thinking about asking B@rt not to assemble mine when I saw the cost of the Norland adhesive in the UK (two to three the cost than in the link you provided); I think I will take a chance with it unpotted!

Thank you for the excellent guide though.

Andrew

Thanks for the compliments guys!

For those of you across the pond, you might want to have a look at these products:

http://www.intertronics.co.uk/products/optintro.htm

They offer thermally cured systems with very similar properties to Norland 61. Opti-tec 5001 and 5012 seem to be the closest matches, low viscosity, low shrinkage, and high cured hardness and transparency. I was told that they offer samples, but was having difficulty with their US distributer.

Norland 61 Typical Properties:

Solids - 100%
Viscosity (25°C) - 300 cP (~300cS)
Refractive Index - 1.56
Elongation at Failure - 38%
Elastic Modulus - 150,000 psi
Tensile Strength - 3,000 psi
Hardness (Shore D) - 85

If I can be of further assistance to anyone, don't hesitate to PM.

That's a good idea.

Nice work & very detailed process description. :thumbsup: I used a slightly different method with scotchtape to seal the holes row by row before filling them with Norland61 & curing them with a UV LED torch which was a very slow, tedious & messy procedure, resulting in tiny bubbles too. Took me about a week and half to do this smaller trit-Ti which I've been wearing as a pendant on a chain for several months now.

Hello flashlight,

Thanks!

That's an interesting design, I recall seeing your picture posted somewhere else. That was the approach I was initially hoping would work, but after looking at the TiGlow, I was pretty sure that it would be a major pain to keep the Norland from leaking everywhere. Looks like your hard work paid off though, not bad at all! I'm a bit of a perfectionist, so this procedure was developed to minimize any cosmetic issues.

Was that custom made for you?

Thanks for the excellent walk through. So inspiring, in fact, that I just ordered a bottle of Norland 61 :naughty:

Well done.
wigregard

Thanks, wigregard. I was a little reluctant to drop ~$40 on a 30cc bottle of Norland which I knew I would never get close to exhausting (before expiration), but in the interest of experimentation I went that route. BTW, this bottle is still useable, although it seems to cure to a slightly straw yellow color now and viscosity has increased a good bit (but noticable only when trying to draw it through the syringe needle). Now that there's an active group buy in the marketplace, it may make sense to get it there instead. But, you'll be paying quite a bit more ($5/cc) compared with buying your own bottle ($1.27/cc), and with your own bottle you can at least repeat this procedure until you're satisfied that you've gotten most of the bubbles out and there are no leaks or other issues.

To update on the status of my encapsulated TiGlows, just ahead of B@rt's next run, I'm happy to report... not a single problem! The one on my keychain has taken quite a few serious drops and still glows like new. No evidence of wear on the surface of the Norland either, looks nice and shiny so it still transmits light perfectly. This stuff seems to be very durable, which makes it well worth the cost IMO.

Hi there im new to this forum can anyone tell me if i could still buy this on in the picture(Trit ice blue titanium)?? I WANNA BUY!!
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