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What is the purpose of a UV light?

TeamMCH

By TeamMCH
in General geocaching topics

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Dgwphotos

+Dgwphotos

Posted
Posted

To be more specific, some night caches will have a clue, or next set of coordinates, or some other info, or just a trail of points leading into the woods, written in UV marker...the only way to read the info is with a UV flashlight, the writing doesn't show up under regular light.

By UV Marker, do you mean something like a sharpie, or UV paint (i.e. cans of paint, or spray paint)?

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dfx

+dfx

Posted
Posted

To be more specific, some night caches will have a clue, or next set of coordinates, or some other info, or just a trail of points leading into the woods, written in UV marker...the only way to read the info is with a UV flashlight, the writing doesn't show up under regular light.

By UV Marker, do you mean something like a sharpie, or UV paint (i.e. cans of paint, or spray paint)?

 

I've used a sharpie-style pen that writes in "invisible ink" - transparent under normal light, but lights up under UV light.

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Dgwphotos

+Dgwphotos

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Posted

I've used a sharpie-style pen that writes in "invisible ink" - transparent under normal light, but lights up under UV light.

 

Hmmm ... I'm already getting ideas for a new hide. Where does one get this type of UV-only pen/marker?

 

Well... we've looked all over the place for such a thing, and couldn't find anything like it anywhere. We resorted to a dedicated night caching store.

How long does it usually last? (In terms of being able to mark) I've been using UV Spray paint, but it's pretty spendy, and this looks cheaper and easier to use. Also, does it fade after a while?

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kunarion

+kunarion

Posted
Posted (edited)
Hmmm ... I'm already getting ideas for a new hide. Where does one get this type of UV-only pen/marker?

Google: UV Invisible Ink

 

I bought a couple kinds of pens and a stamp pad. The "blue" ink glows best, but red is available, too. There's even slow-drying ink, so you can see what you're writing (it's all quite interesting, actually). You can probably get a great deal on UV penlights on ebay, with free shipping.

 

You may also be able to buy powdered phosphorus at a paint store, and mix it with clear paint or epoxy. That probably would never fade. It's just an idea I had, I've never tried it.

Edited by kunarion
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fizzymagic

+fizzymagic

Posted
Posted

By the way, UV is not UV. The flashlights that you get are so-called "long wavelength UV" that will make most fluorescent dyes light up nicely and can be used with the UV ink. They are also great for "charging" glow-in-the-dark materials.

 

Short-wavelength UV is used for sterilization and can put your eyes out, among other things. It's also useful for finding fluorescent minerals, many of which do not fluoresce under long-wavelength UV light.

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kunarion

+kunarion

Posted
Posted (edited)

I used Clear Neon Spray Paint, but it's around $21 a can, and only lasts about a year in the field.

The ink pen lines fade rather quickly, too, outdoors. It depends on the writing surface. You can coat the ink, or put it into a container to reduce exposure to the elements, which may help. The pen ink behaves much like Magic Marker ink, except for being invisible.

Edited by kunarion
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niraD

+niraD

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Posted

Owners of local UV-based caches have mentioned that the fluorescent ink/paint lasts longer in the field if you protect them from exposure to the sun. They still need to refresh the fluorescent ink/paint regularly, but the maintenance is more manageable when it's used in sheltered locations.

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teamvoyagr

+teamvoyagr

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Posted

I used Clear Neon Spray Paint, but it's around $21 a can, and only lasts about a year in the field.

The ink pen lines fade rather quickly, too, outdoors. It depends on the writing surface. You can coat the ink, or put it into a container to reduce exposure to the elements, which may help. The pen ink behaves much like Magic Marker ink, except for being invisible.

 

As with any cache that has a written hint in the container it is best to laminate the clue "card". In this way you protect the clue from the environment. I still wouldn't leave it unprotected. I'd put it in a container. Cache At Night has paper and self-laminating pouches for this purpose.

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BlueDeuce

+BlueDeuce

Posted
Posted (edited)

Scorpions

Good answer.....that's what immediately came to mind whether that be the correct answer or not.

 

I've heard that Scorpion caches are automatically a 5/5 due to the equipment requirements and the danger. A nasty piece of business but hey, that's caching.

 

 

bd

Edited by BlueDeuce
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TeamMCH

+TeamMCH

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So now I find myself driving around, continually scanning the area for good places to develop a night cache!!

 

Was at the mall and wondered about creating a multi-cache where the stages prior to the final are the coordinates of the next stage written on lamp posts, guardrails, backs of signs, etc. That brings to mind two questions:

 

1) I'm in central Indiana - how quickly would the invisible ink pen wear off of a lamp post, sign, etc? How often would I have to do "cache maintenance" and reapply the ink?

 

2) Because there isn't a physical container - just writing on a permanent fixture - would it be legal for those stages of the multi to be less than 0.1 mile from another cache?

 

Getting intrigued by the possibilities.

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niraD

+niraD

Posted
Posted

The saturation guideline addresses "physical elements" of geocaches, not just containers. The saturation guidelines applies to any physical stage; that is, "any stage that contains a physical element placed by the geocache owner, such as a container or a tag with the next set of coordinates."

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kunarion

+kunarion

Posted
Posted (edited)
how quickly would the invisible ink pen wear off of a lamp post, sign, etc? How often would I have to do "cache maintenance" and reapply the ink?

This depends a lot on climate and weather, but it will last a few months, fading more every day. Find a surface outside your home to test it. When you go to re-ink your lamp post, you'll first have to clean it, then trace new lines using a black light (so you can see the old lines). And the lines can weather differently than the rest of the lamp post, so it's likely that the solvents in the ink will either etch the coords into the post, or corrode differently, so that the writing becomes more and more visible -- and permanent. So find an object where it doesn't matter if the "invisible" writing becomes etched onto it.

 

Consider fluorescent minerals, too. Rocks don't fade.

Edited by kunarion
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niraD

+niraD

Posted
Posted
And the lines can weather differently than the rest of the lamp post, so it's likely that the solvents in the ink will either etch the coords into the post, or corrode differently, so that the writing becomes more and more visible -- and permanent.
If you apply the fluorescent paint/ink to your own "game pieces", then you don't need to worry about damage to lamp posts and other objects. But you may want to protect your night-only UV cache from being hacked during the daytime.

 

One technique I've seen is to use fluorescent and non-fluorescent paint that look similar in the daylight. Apply the paints in a way that hides the information unless you can tell which paint is fluorescent under UV light. For example, you could use the paints to create a simple 7-segment digit. In the daylight, it might look like this:

 .....
/     :
/     :
/     :
,,,,,
;     \
;     \
;     \
'''''

But in the night, under UV light, it might look like this:


#     H
#     H
#     H
*****
     %
     %
     %

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teamvoyagr

+teamvoyagr

Posted
Posted
And the lines can weather differently than the rest of the lamp post, so it's likely that the solvents in the ink will either etch the coords into the post, or corrode differently, so that the writing becomes more and more visible -- and permanent.
If you apply the fluorescent paint/ink to your own "game pieces", then you don't need to worry about damage to lamp posts and other objects. But you may want to protect your night-only UV cache from being hacked during the daytime.

 

One technique I've seen is to use fluorescent and non-fluorescent paint that look similar in the daylight. Apply the paints in a way that hides the information unless you can tell which paint is fluorescent under UV light. For example, you could use the paints to create a simple 7-segment digit. In the daylight, it might look like this:

 .....
/     :
/     :
/     :
,,,,,
;     \
;     \
;     \
'''''

But in the night, under UV light, it might look like this:


#     H
#     H
#     H
*****
     %
     %
     %

 

Certain types of fishing line are UV reactive. You can do a similar thing using reactive and non-reactive fishing line. I have a photo on my phone of this. I should upload it for reference ... but back to work.

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kunarion

+kunarion

Posted
Posted
And the lines can weather differently than the rest of the lamp post, so it's likely that the solvents in the ink will either etch the coords into the post, or corrode differently, so that the writing becomes more and more visible -- and permanent.
If you apply the fluorescent paint/ink to your own "game pieces", then you don't need to worry about damage to lamp posts and other objects. But you may want to protect your night-only UV cache from being hacked during the daytime.

 

One technique I've seen is to use fluorescent and non-fluorescent paint that look similar in the daylight. Apply the paints in a way that hides the information unless you can tell which paint is fluorescent under UV light. For example, you could use the paints to create a simple 7-segment digit. In the daylight, it might look like this:

 .....
/     :
/     :
/     :
,,,,,
;     \
;     \
;     \
'''''

But in the night, under UV light, it might look like this:


#     H
#     H
#     H
*****
     %
     %
     %

 

Certain types of fishing line are UV reactive. You can do a similar thing using reactive and non-reactive fishing line. I have a photo on my phone of this. I should upload it for reference ... but back to work.

Very cool ideas! I have a rock light, for minerals. Two different wavelengths, where things glow differently in different light. I've imagined some pretty evil clues involving that. Oh yeah.

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fizzymagic

+fizzymagic

Posted
Posted
I have a rock light, for minerals. Two different wavelengths, where things glow differently in different light. I've imagined some pretty evil clues involving that. Oh yeah.

 

Just be aware that one of those wavelengths (the shorter one) requires pretty expensive gear. Typically over $50 a light. That's because the filters used to get rid of the non-shortwave UV light are very expensive. Someday they will make 255-nm laser diodes and it will be cheap, but a lot of people will hurt themselves.

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kunarion

+kunarion

Posted
Posted (edited)
I have a rock light, for minerals. Two different wavelengths, where things glow differently in different light. I've imagined some pretty evil clues involving that. Oh yeah.

 

Just be aware that one of those wavelengths (the shorter one) requires pretty expensive gear. Typically over $50 a light. That's because the filters used to get rid of the non-shortwave UV light are very expensive. Someday they will make 255-nm laser diodes and it will be cheap, but a lot of people will hurt themselves.

I thought one fun thing would be a sig item that had some kind of clue which glowed in "ordinary" household blacklight. Superimposed, ink that's only visible with a specialized rock light. I dunno, it was just a thought.

Edited by kunarion
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jbravofaria

jbravofaria

Posted
Posted
Hmmm ... I'm already getting ideas for a new hide. Where does one get this type of UV-only pen/marker?

Google: UV Invisible Ink

 

I bought a couple kinds of pens and a stamp pad. The "blue" ink glows best, but red is available, too. There's even slow-drying ink, so you can see what you're writing (it's all quite interesting, actually). You can probably get a great deal on UV penlights on ebay, with free shipping.

 

You may also be able to buy powdered phosphorus at a paint store, and mix it with clear paint or epoxy. That probably would never fade. It's just an idea I had, I've never tried it.

 

Has anyone tried the powdered phosphorus solution? does it lasts longer?

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teamvoyagr

+teamvoyagr

Posted
Posted

For UV caches there are three choices for marking - ink, paint or monofilament. UV ink is not weather safe so you will have to protect it some how. Whatever marking type you use apply it over a non-UV reactive media. White paper that you typically print on is very UV reactive.

 

For lights you have three choices:

 

~400nm wavelength with lots of purple light and AAA batteries for about $12.50

395nm with a little purple using AA batteries for about $30 (this is the light I'd recommend)

365nm with almost no purple (black light) using AA batteries for $40.

 

For most geocaching uses the 395nm is fine. There are a few cases where you will need 365nm UV but those are very rare and you could probably still get by with the 395nm lights.

 

As mentioned elsewhere all of these products are available via Cache At Night.

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thebruce0

+thebruce0

Posted
Posted (edited)

This coming from a region of southern Ontario that's filled with night caches and tricky UV/IR/laser tricks ;).

 

If you want to experience night caching (and more than just using flashlights), look around Milton, Ontario. Gold mine. :laughing:

Edited by thebruce0
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