Phosphorescent pigments

[tocket]

I just received a few kilograms of phosphorescent pigments in various colors. Not that crappy old green copper doped zinc sulfide that we've all seen in various cheap glow-in-the-dark products, but high quality europium doped aluminates. They not only glow stronger than zinc sulfide, but also longer. Unfortunately they're also a fair but more expensive.

The colors I have are:
Green (520nm , europium doped strontium aluminate)
Blue (europium doped strontium calcium aluminate)
Purple (europium doped calcium aluminate)
Orange (europium doped yttrium oxysulfide [this is a completely different breed and very expensive]).

Now to the interesting part; applications. What I intend to do with these pigments is to coat screens with them, then scan a BluRay laser over that screen. Since these pigments are readily excited by 405nm light, as I'm sure you've seen before, I can hopefully make some cool patterns that remain even after the laser is powered off. This should look interesting, as you will have a violet laser with orange/green/blue afterglow. Unfortunately I do not yet have any bluray lasers and the ones I've ordered are weeks away from arriving.

Another application is of course body paint. When is the last time you saw someone glowing in the dark? For this I figured latex would be a good base (albeit somewhat kinky), but then I realized that latex comes from a tree. Trees typically contain water, something that the aluminates are not very fond of. I've always wanted to have a bottle of liquid latex to play with though, so I think I'll test latex anyway.

Oh, and this thread is definitely worthless without pictures...

[allthatwhichis]

Mmmmm, pictures... Looks like a new type of rave drug. How are you going to coat your screens?

[tocket]

That's a good question. I will need to experiment with different binders. So far I've only tested nitrocellulose. It works fairly well, but is somewhat brittle (and very flammable). Next up is some petroleum based products.

It would be nice with some kind of aerosol solution for applying it, but I don't have the equipment for that, so I think I will just use a normal brush to paint the screen.

[Tomcat]

so are you going to use a scanner with a 405 in it for the patterns? that would look pretty awesome for slowly fading patterns

for a project i suggest a scanner (rgy) and add the bluray as the blue and use blue in your show peogram for the special effect with the rgy doing animations (dim the powers though) on top

for the areasol try to disolve it in your binder and then use a pumpaction spraygun (like the floorwipe bottles) but make sure the parts are not soluable in your solvent

<hippie dance rave> tyedye a shirt with some pigment and normal dyes for the ultimate nightclub shirt </hippie dance rave>

[mixedgas]

try good old ordinary clear testers enamel for the binder. Avoid polyurethanes or polycarbonates, they adsorb UVA like mad. Some day I might bring to salem my special polymer doped with a dye that turns from blue to white when UV hits it, the "daylight" laser show :-)

Steve Roberts

[Jem]

tyedye a shirt with some pigment and normal dyes for the ultimate nightclub shirt </hippie dance rave>

Did you see Rob's (Stanwax) Tee Shirt at UKLEM???

Jem

[mliptack]

Nitrocellulose, I am surprised you tried it... did you buy real nitrocellulose, synthesize it yourself or did you just dissolve ping pong balls in acetone?

Maybe I am speaking from experience from all three of those possibilities. Its funny how flammable ping pong balls are!

I am glad you are trying this. I am wondering how well it will work with a diode that is operating at <5mw. I've been meaning to try - just too little time.

[tocket]

Nitrocellulose is actually often used to coat wood. For example there's a lot of IKEA furniture that has NC lacquer. I did not synthesize it myself, as sulfuric acid is really hard to come by in Sweden. Far too valuable to make NC from! Instead I just bought a bucket of partially nitrated cellulose (pyroxylin) that I use for pyrotechnics and lacquers.

So far I've tried clear coat (alkyd/polyurethane based I think, really hard to find out) and some different beeswax compositions (for body paint). The clear coat is working very well and does not seem to absorb that much in the NUV region, but as it contains polyurethane it surely has "light stabilizers" in it as well.

Beeswax is fun to work with, but I had one very unpleasant experience. I was experimenting with different solvents for it, but none seemed to work well. That's when I turned to my beloved bottle of dichloromethane (DCM). For those of you who are not familiar with that solvent I can say that it is truly fantastic. Whenever my students ask me what solvent to use to dissolve compound x in the lab my answer is DCM, without even asking what compound x is (in organic chemistry, if DCM doesn't work, they've done something wrong in 99% of the cases). It's very closely related to chloroform, but a little safer to work with. Needless to say, it worked great for dissolving beeswax too, so I proceeded to mix in some pigment and ended up with a very neat "paint". As I applied this paste to the top of my left hand it felt very cold as the DCM evaporated (boiling point 39°C). This was expected and nothing to worry about. What I did not expect was that after about 1 minute the sensation would turn from ice cold to burning hot! It felt like the veins in my hand were on fire and the hand was swelling up. Luckily the sensation passed after a few minutes, but I decided not to try DCM again. That, and it's illegal to use...

I feel clear coat is probably the way to go, but I did not think expect it to be so challenging to find one that doesn't absorb NUV. Thinking about giving Akzo Nobel a call. It's also hard to find any UV/Vis spectra for these polymers. Based on the structure though, I would say polyurethane doesn't absorb UV. Polycarbonate was never even considered though.

The really big shame here is that I don't yet have a 405nm laser (10 diodes soon on the way though). I do have some UV fluorescent tubes and UV LEDs, but they're really no substitute for a laser. Anyone have a good source for low wavelength UV LEDs by the way? Looking for something around 360nm.

Is anyone interested in buying some pigment/paint? The minimum quantity I could order was 1kg of each color. I doubt I will use up 4kg myself. Need to know if it's worth starting a thread in Buy/Sell/Trade. Prices would be between 0.06 €/g (purple) and 0.15 €/g (orange). I can prepare a paint (clear coat based) for 0.05€/ml to 0.1€/ml. Shipping seems to be €6 for <2kg to anywhere in the world. Can send a few <20g samples for €2 a piece using packaging materials I have lying around.

Actually, I would really like to see this stuff in action with a bluray laser. If someone is willing to make a video I will send a completely free sample.

[mliptack]

Thats too bad Sulfuric acid is so expensive. Its -for the most part- readily available almost anywhere. Its the nitric acid that is hard to come by.

Also I have had mixed experiences with nitrating cotton- many times the reaction (probably due to impurites in the cotton) would spiral out of control heating to a point that would be impossible to keep cool and start to produce the brown gas (cant think of the name of it - same stuff you get when you put copper into nitric acid). So I always worked in small batches. I still have plenty of nitric acid - in fact I use it for aquarium uses.

I guess I just fell out of my chemestry days - maybe I'll have to have some fun with the stuff I have left over. I am pretty sure I still have some potassium metal and lithium - those are always fun.

As for the free sample of pigments. I would be happy to try this out for you. However, it would take a good week - week and a half before I would be able to find the time to do so.

-max

[mixedgas]

So far I've tried clear coat (alkyd/polyurethane based I think, really hard to find out) and some different beeswax compositions (for body paint). The clear coat is working very well and does not seem to absorb that much in the NUV region, but as it contains polyurethane it surely has "light stabilizers" in it as well.

When maintaining a 351 nm argon at work (the department of polymer science and polymer engineering, Univ of AKron) We found that ordinary polycarb safety googles @ ~2 euro a pair worked better then the 400$ off the shelf glass laser goggles. Try Testers clear model plane enamel or its european equavalent. If you can get it there , Norland 61 is a uv curable phtopolymer we used in our UV interferometric patterning lithography, it has good UV transmission once cured. only a very weak yellow green flourescense with no phosphorescense of its own. UV adsorbption once cured is weak for thin films.
Its also somewhat flexible when cured.

I'd love to buy a few grams of the orange long persistance one if you go into sampling.

Steve Roberts