Phosphorescent Paint and UV Excitation

Wow! Thanks TV!

Just to certain I didn't accidentally mislead you: I do intend to illuminate the display continuously with an LED in the Ultraviolet wavelength.

I don't need long term "stored" luminescence when the light source is off; only brightness when the LED is on.

Are your suggestions still the same?

Was my assessment about organic materials correct?

Thank you!

L.J.

Actually Jag, you may opt for the phosphorescence anyway if there's a chance you will need to be able to read the dial in the case of a power failure.

Insofar as organic fluorescence goes, fluorescent dyes are commonly added to paper and cloth to give it a 'brighter' look under ordinary daylight. Most laundry detergents fluoresce brightly in UV. If the soap adverts say "whiter, brighter wash!" or some such, you can count on it that a blue fluorescent dye was added to the mix. To see this for yourself, shine a blacklight on your laundry soap in a darkened room and see what happens.

As you're going to use this in an outdoor application, stay away from red, orange, and yellow fluorescent colorants. These fade quickly under the short-wave UV found in daylight. Greens and blues last longer. Some "industrial orange" paints, for example, are yellowed and faded within two weeks of application.

Under UV, those Sr-based phosphors glow very brightly while illuminated. Much more so than ZnS phosphors. Order some and play with it! It's cool stuff even if you opt for something else.

Kind regards,

TV

When I get back home (I have to run an errand) I'll take some pix of my phosphor-powder "collection" and post them here. I think you'll see the difference; especially when I place a vinyl ZnS sheet next to the Sr phosphors and take a few time-lapse pix after turning off the UV. The ZnS phosphor will fade quickly and will appear dark even after a few minutes.

Kind regards,

TV

TV, the protective spray coating of clear polyurethane does not inhibit the paper from glowing under UV light. A comparison of the coated and uncoated paper made that clear.

There are uncertainties associated with this project, as there usually are when something new is being developed.

In the interest of expediency, I will use the coated white paper just to complete the tests and when I'm satisfied that the entire design works as planned, thats when I'll develop a brighter background using the chemistry you suggested.

Thanks again for your generous support.

L. J.

From your posts I have concluded that you are going to degree in a camshaft in the dark. Is there some contest to see who can build a motor in the dark?

That contest was already held back in 1965 using a Dyna Panhard engine. I lost because I couldn't find the drain plug blindfolded. The guy who won reassembled the engine in half the time I did not.

That was OK. I beat him in the time taken to drop a VW Beetle engine, change the clutch and reinstall the engine.

As for my device, no I am, degreeing a camshaft in the dark. I'm aiming a telescope using an Alt-Az mount. Same method as aiming a cannon only not as much noise!

L. J.

No noise? Why bother? Wait. Who's window are you looking at?

There is a product you should look into. "electroluminescent" It is very thin flat sheets of plastic that will glow, similar to Glow In the Dark. Very low power is applied to the sheet. It was used on the factory Audis in the American Le Mans series. You would just mark your readings on the sheet with dark markers, or paint. When charged, the light does not shine through the paint, and is very readable. I did a google search, and hit a few that sell the stuff. It might be a good bet for your final version. For automotive use a transformer is used to raise the 12 volts to the higher voltage needed. Give a look.

" For automotive use a transformer is used to raise the 12 volts to the higher voltage needed."

I'm familiar with the racing application having crewed for a team awhile back. Thanks for the suggestion but that is far too costly, two heavy and too complex for this application.

L.J.

A telescope it is! Well, then, Jag. Will you be taking photos? There's a reason for my question.

Will you be taking photos? There's a reason for my question.

There's a reason for everything we do and, sometimes, we even know the real one!

If by photos you mean astrophotography, someday I will get out from the load of other demands and develop some skills in that area. Thus far, I've not tried too hard and, as a result, the results have been underwhelming.

CCD imaging is quite the thing these days and the results some are getting, even with modest equipment, are impressive.

If I've not warmed up to that activity as some others have it's because I love building scopes and have demonstrated more passion and creativity designing and building them than I do using them.

Besides I'm a wet eyeball Now observer. I prefer seeing those marvelous images with warm wet eyes in real time. If I want impressive images I can always go to the Hubble section of NASA's web site and look at what the Hubble did.

Why DID you ask? Please! Be kind!

L. J.

Hey Jag,

I asked about taking photos (yup, astrophotograpy) because while the UV from the LED might not appear bright to the naked eye, it'll wreak havoc with your time exposures.

CCDs are generally most sensitive in the red/IR region, but over an extended exposure the UV -- even though it is slightly beyond the other end of the visible spectrum -- can saturate the CCD chip.

Speaking of CCDs, most digital color cameras incorporate an IR filter to keep the colors from washing out. Some higher-end cameras allow you to disengage it for work in the IR spectrum, but most don't.

CCD (and MOS) cameras made for color astrophotographic work use monochrome imagers (one cell per pixel) and a filter wheel. Typically three exposures are taken; one each with the red, blue or green filter in place.

The filter wheels are more useful in spectral work if the filters themselves can be replaced with other filters (dichroic filters, for example) that allow light from the oxygen spectral line through, for instance, but nothing else. This can get expensive, as you might have guessed.

I'm always kind, btw. Sometimes I wake up grumpy, of course, but most times I just let her sleep.

Hmmm... sounds like you must be a genius to devise something like this! How imaginative of you... bummer about the glue...

Even though you have chosen to use white paper for your dial (whatever works, use it!), I'll go ahead and post some pix I took last night. Firstly, because these phosphors are cool and (2) to taunt you about the fun you're missing!

The phosphors in daylight and UV

In UV only

Five seconds after lights out.

Ten seconds after lights out.

Twenty seconds after lights out.

The central rectangle is a sheet of clear vinyl over ZnS. The inset rectangle is clear PVC film over Sr-based green. Going clockwise from the left are white, red, 'pink', orange, 'yellow' (more a yellow-green), green, aqua, blue, and violet phosphors.

The red and 'pink' phosphors are ZnS-based. Notice how quickly they fade. ZnS-based red phosphors have a very low quantum efficiency to start with so they don't even start out bright.

The brightest by far is the aqua phosphor. It and the green are noticeably bright even 12 hours after exposure to light. As an experiment, a few years ago I exposed the green and aqua phosphors to UV for 15 minutes, then put them in a light-tight box for 48 hours. When I opened the box in my darkroom, they were still glowing. Dimly, but glowing.

Pretty incredible stuff, if you ask me. I'm going to order some of the new Nichia phosphors and test them too.

Kind regards,

TV

The white copy paper and many textiles have optical brightening agents (OBA's) in them which are stillbenic dyes that are UV active and can add a blue tint to white surfaces which makes them appear brighter. Bayer makes some of the ones I've used. I've actually painted kids with these OBA's and we went "Cosmic Bowling" under black lights and they were easy to spot in the crowd. They glowed as long as the UV lights were on.

Ok you got me excited, now what?

Cool phosphores, Now I'll just have to think up some apps for them.

Brad

"Now I'll just have to think up some apps for them"

OK UV, I'll start

How about door knobs so people can find and open doors if the lights fail.

On flashlight handles so you can find them.

On the ignition lock and door lock of your car.

On your keys should you drop them in the dark.

On you cat's collar.

How about on the keys of your keyboard so you can still read them in dim light.

The corners of furniture so you can see them before you find them with your hip.

On the lip of each stairwell's step

Your turn!

Paint eyes on your neighbor's windows

Stars on the ceiling of children's rooms

The cove moldings in public buildings

The reset levers on circuit breakers

Faces on the back wall of the basement, or garage

Good painter, bad painter. Decisions, decisions, decisions.

Ok Laughing Jaguar,

How about:

Paint jobs on vehicles and cars (killer designs and advertising);

Screen printed Teeshirts (after dark effects);

Signs For marketing ( Ing on the park bench after dark);

Billboards (no lights needed);

Concert Paraphernalia (no need to flick my bic);

Concert posters (day and night);

Book covers (Even on a dark shelf it calls to you);

Outside doorknob inlays (cool designs for cool houses) ;

Street Lines (all night long even the parking lot);

Walkway colorant ( is it just me or does the sidewalk have light coming out of it?);

Bike paint (who needs reflectors?);

Anti-slip surface paint (industrial stairs will never be the same);

Power tools plastic ;

Snow skis for night skiing;

Plane markings;

Runway markings;

Your turn.

Brad

In the mid eighties there was a company selling automotive paint that would glow in the dark. It was sold under the name of Moon Glow paints. Hot Rod, or Car Craft had a cover with a dragster painted with it. It came in a few different colors, and there were tints that could be applied over it to change the color.

I still have 4 cans that I haven't found anything to paint with yet. Any ideas?

"Dupli-Color" is a familiar name so when I spotted an aerosol can marked "Illuminite", I grabbed it.

My purpose in trying it was to see what I could do to help prevent people from bumping into my telescopes at star parties.

The can specifically states "High intensity over white" so I painted a telescope tube white and when it was fully cured sprayed on the Dupli-Color.

Worthless seconds after turning off the lights, less than worthless after a minute.

The test I conducted that started this string was essentially the same, using the same Dupli-Color paint except instead of charging the phosphorescent paint with sunlight or fluorescent lights, I used a 3 fluorescent "black-light" bulbs emitting a narrow UV band light. What little glow the painted disk displayed was more from the white paint.

I'm going to go with what The Voice suggested. Seeing is believing and, as you can see, he knows his stuff.

L.J.

I agree. He has more info on luminescence than any one i ever heard from. I also bought some Duplicolor glow paint from Grainger. I guess i should not expect too much. Have you tried White Out? My daughter used it once for some experiments. It was very good at reacting to the UV light. You will need to clear coat for protection from weather.

The illuminated surface is just one of three parts needed to make the degree wheel.

The bearing surface on which it rotates is the outer gray piece.

The white disk is the primary structural part. It's outer face gets painted with the "phosphorized" paint.

The black disk is a piece of satin finished laminate that has been slotted on a band saw every 2.5 degrees. (It's for use on a planetary scope of modest aperture. Finer resolution isn't necessary)

The disk gets glued to the painted wood disk. The white, phosphor sensitized paint is visible through the cuts.

A light emitting diode in the UV wavelength (not shown) will excite the paint and it will glow brightly but only through the slits in the degree wheel.

A mask, not shown here, with a small aperture, perhaps 0.625" will cover the entire face of the degree wheel. The small aperture will only allow the user to see a small portion of the degree wheel and the numbers (not shown) needed to locate the object in the sky.

Using white out concerns me as the adhesive that secures the laminate to the face of the bearing needs something with good adhesive properties and frankly, I doubt the white out offers that.

The previous image is a rendering of a portion of the parts modeled in the 3D engineering software I use in my work.

The second image is an actual photo of the laminate shaped and slit on the bad saw (0.020" cuts) and ready for application. The surface isn't damaged. It still has a protective film coating waiting for removal.

The drawing you see of 2 slotted disks in the background are nothing more than a laser print out of the degree wheel drawing file. I generated that from the 3D solid model (Drawings are an automatic byproduct of modeling parts in SolidWorks software) I merely plot the drawing file to the printer, cut out the appropriate geometry, spray paint it and then hack away at it.

Even the least expensive printer will produce accurate 600 dpi resolution which is far better that I can do using the old fashioned machinist ruler and scribe method.

Optically white out is perfect for another application however. I may use it to accent degree marks on the barrels of my binoculars, which also are fun for sky gazing but impossible to read in the dark.

L. J.

Very nice reply. Thank you. I have a truck with a semi custom console for the extendable waterway. The cover is manufactured from semi transparent plastic (try to picture natural colored nylon sheets 1/2" thick). The manufacturer mounted small clearance lights below the plastic. It allowed the panel to appear to light up and see all of the switches.

Could you use a round translucent plastic disc instead of wood, transfer your degree template to the plastic with the saw, then ink over the outside surface of the disk. Might be able to use a permanent marker for that. Then you could mount a stationary led behind the disk that would light up the area visible behind the aperture.

"Could you use a round translucent plastic disc instead of wood. . . ?"

Yes I could however a disk that size would require a much larger amount of light to insure sufficient illumination all around the perimeter. More light means bigger batteries and either more LED's or a brighter ones. That material is also more costly and more difficult to work with.

I only need one LED and I will mount it at the 6"o'clock position behind the mask with the aperture and very close to the degree wheel.

I just returned from Radio Shack where I purchased two UV LED's for under $2.00. make shift test in a dark shop showed excellent results.

Three calls to Nichia failed to get me closer to a Nichia solution and I found myself caught up in one of the classic "Sorry Sir, this is not my table" situations.

I need to button up this LED/Degree wheel design. I've other projects I must attend to.

When it's done and in service I'll take pictures. I promised Voices I would do that.

Thanks

L.J.

I'm replying to my own post so as to correct an error.

In my post I wrote:

"The drawing you see of 2 slotted disks in the background are nothing more than a laser print out of the degree wheel drawing file. I generated that from the 3D solid model (Drawings are an automatic byproduct of modeling parts in SolidWorks software) I merely plot the drawing file to the printer, cut out the appropriate geometry, spray paint it and then hack away at it."

The last sentence of that reflects what can happen when it's late and your tired.

What it should have said was:

I merely plot the drawing file full size to the printer, cut out the appropriate geometry, spray adhesive on the back of it, glue the drawing to the raw material as you see here

and then hack away at it, using the drawing as a guide.

It's not necessary to have expensive 3D engineering software to do this. I am fortunate to have it so I use it.

This idea of plotting full size drawings instead of time consuming and often inaccurate hand layouts can be done by virtually anyone with the simplest of 2D drafting packages.

The time saved doing it this way adds up and becomes substantial when many prototype parts of the same geometry need to made.

L.J.

Hi LJ,

3M makes a very nice material called Quick Mark (previously Dyna Mark, previously Scotch Cal -- a contraction of Scotch and Decal, I'm sure), and I use Quick Mark for my control-panel artwork, dials and so forth.

In the Bad Old Days I'd draw my artwork by hand on vellum and then transfer it to the Quick Mark (Scotch Cal then). Neat thing about Quick Mark is that it has a translucent, self-adhesive backing that comes in different colors. You can even get it in aluminum. Some of my panels (mostly for home projects) have digital displays and the red Quick Mark overlay gives the panels a very nice, professional-looking 'dead-front' appearance. The film has come a long way since its intro as "Scotch Cal." It is very tough and suitable for outdoor service.

Here are Quick Mark's specs.

bob_c asks: "I still have 4 cans that I haven't found anything to paint with yet. Any ideas?"

See Post #17

LJ,

Check out this vendor for multicolor, high-persistence (HP) Sr-based paints and this one for Sr-based HP vinyl/PVC sheet.

You can also buy Sr-based self-adhesive Inkjet film here. This sounds pretty cool if you want to print your dial artwork directly on film that you can apply to the face of your degree-wheel. They don't say whether you can rear-illuminate this stuff or not. I don't know whether the film backing -- if any -- is transparent to long-wave UV, but it may be worth ordering some just to try it out.

Speaking of UV LEDs, a couple of years ago I bought 2 bags of 100 each UV LEDs from a company based in Hong Kong (but had an office somewhere in Illinois, I think). As I recall, each bag cost all of 15 bucks. A bargain considering how few drawbacks these LEDs had compared with the premium Nichia LEDs I normally use.

One drawback was that the clear epoxy compound they mold these LEDs from has a bit of blue fluorescence to it.

The other was that there was a bit of variation in the intensity.

The vendor also sells UV-LED flashlights/torches having around 40 ea 400 nm LEDs per, for just 10 bucks a pop. The switches on the things aren't anything to write home about, but for 10 bucks it was worth buying a couple just to try them out.

Let me see if I can find the invoice and I'll get back here with the info asap.

Kindest regards,

TV

"Check out this vendor for multicolor"

I did and it's the best resource thus far. As much as they promise, that other manufacturer of LED's and phosphors never responded to my inuiry.

I'm going to complete this project with the UV LED's I bought at Radio Shack.

After the Proof Of Concept model is operational, I'll advance the performance using better materials.

You have a been a valuable ally in this pursuit and extremely generous.

Thank you!

L. J.

My pleasure. Thanks!