Tuesday, January 12, 2010

Glow-in-the-Dark sketch wall and LED pens

I've finally realised one of my childhood dreams; I'm now the proud owner of a glow-in-the-dark wall - just don't tell the landlord!

I've had some glow-in-the-dark paint knocking around for quite a while and was inspired to do something with it when I saw this post on hackaday.com - "Record player display sans POV". I thought "the kids" would have a lot of fun using LED flashlights to write on something that was phosphorescent.

To start with I just coated some stiff card with the phosphorescent paint and hacked together a simple UV-LED flashlight. The flashlight design was taken from this Instructable - "Make A Mini LED Light". I found it while trying to find ways to make my own battery holders for a more standard flashlight, but this idea was so simple and small that I decided to go with it instead. All I did was to substitute a UV LED in place of a standard one.

After making the prototype I showed it off to "'er indoors" (this may not mean much to you if you didn't grow up watching "Minder" in the U.K.). Her response was a little unexpected - "Hmmm.... why don't we paint the wall with glow-in-the-dark paint? That way loads of kids can play at once!". So that's what we did :) We isolated a good amount of wall with painters tape, we just wanted it to be slightly taller than the kids. Then we put on 2 coats of white primer, 3 coats of the glow-in-the-dark paint and a couple of layers of varnish (so the kids didn't immediately scrape off the latex based glow paint). After removing the painters tape, I was pleasantly surprised to see that the wall didn't look much different.

Unfortunately, my night time camera skills leave a lot to be desired (i.e. they're crap), so I don't have many pictures of the kids playing with the wall. I can say that they were very excited and played with it for days & were very keen to get all their friends to play too whenever they came over. At one point we had a complete sea-scape covering the whole canvas with storm clouds, jellyfish, 'normal' fish and deep sea monsters. In the picture below I'm holding one of our home made light-sabers next to the wall in an attempt to allow the camera to focus (see this filthwizardry post for more lightsaber fun- "balloon and torch lightsabers").

I think one of the favourite activities, however, was with an old SLR camera flash. Get the kids up against the wall and blind them with the flash. If they recover (ok, you could just tell them to close their eyes) they'll get to see themselves glowing in silhouette form on the wall .

Hmm... ok, maybe it was one of my favourite activities as well.

After a couple of days playing, I ended up buying some LED keychain flashlights (like these from Amazon) as I quickly ran out of parts.

Here's a few in-production pictures of the ones I made:
I made 4 to begin with. All you need is a pushbutton, a UV LED, a coin cell battery and holder (and a soldering iron + solder for connecting it all up).

Connect the positive lead of the LED to the positive battery holder connector, cut off the rest of the lead so it doesn't get in the way, then attach the pushbutton to the negative battery holder connection and the negative LED lead. That's it!

Here's the first one working (nice purple glow). Some hot glue made for good protection and electrical tape wrapped around the base of the LED helped to focus the beam.

You should probably use a resistor to protect the LED... The datasheet for my LED stated that it required 3.2V to operate and the coin cell is only rated at 3V so I decided to leave the resistor out.

Important: Bright lights/UV lights can damage your eyesight. Do not shine the lights into anyone's eyes and make sure any kids playing with these are supervised and told to shine the light only at the wall. Extra care should be used when using UV light - the human eye can not detect it (i.e. you can't see it) which makes it easier to overexpose your retina as you don't have the same pain response as with intense light in the visible spectrum.

If you're nervous about this then the standard keychain lights work pretty well. The homemade UV ones just give a longer lasting glow.


The Walkers said...

This is awesome.....we have to do this for the boys! (ok and maybe a little for us too.)

Kami said...

SO cool! I want to do this, so badly!

Psycho Bill said...

Blue laser pointers will work great as well, used them for Halloween on my makeup.

Anonymous said...

Forgive my ignorance regarding writing with on a phosphorescent surface with light. Does the image persist or is it temporary? How long does it last?

PaulBo said...

"Psycho Bill": I really wanted to play with a laser pointer, but I don't think they mix well with little kids.

Anonymous: The image is temporary and the length of persistence depends on the intensity, frequency and duration of the light you use. Ours last around 2 minutes and then the canvas is blank again for more fun.

PaulBo said...

Pat: it's almost Pancake day, so you'll have an excuse to play with the wall soon :)

Anonymous said...

that's cooooool

morcheeba said...

I totally agree that blue laser pointers aren't for kids. I just bought some from the orient, and while they were marketed as <5mW and are labelled <5mW, they measured a scary 35+ mW on the laser power meters we have at the office!!

WOOWHO said...

question: you have a giant section of glow-in-the-dark wall - what prevents the whole section from glowing when you turn the lights out? i'd think it would be hard to "write" with the light as the whole thing would be glowing, yet there it is working, and i'm just confused. i want to do this for my kids - it is an amazingly cool idea, and i'm currently in the process of redoing their room, so the timing is perfect. thanks!

Anonymous said...

OMG this is so cool! We're in the early stages of repainting my 4 year old boy's bedroom and this is PERFECT.

Where did you get the paint? Is it a mail order thing or can it be purchased at HomeDepot/Lowes/Etc. ?

PaulBo said...

@WooHoo: you're right, the wall will glow for a little while when you turn the lights off, but it should fade pretty quickly. For us the brightness was low and we could start writing/playing straight away.

@sarchix: we got 3 tins of "Rust-Oleum Glow In The Dark" from Home depot. It was around $8 a tin. You can also get it from Amazon:

Rust-Oleum 214945 Glow in the Dark 7-Ounce, Glow In The Dark

Incidentally, we also picked up some Rust Oleum blackboard paint from HomeDepot and turned a thrift store mirror into a blackboard for the kids.

Anonymous said...


Thanks a million! I'm linking this to my blog over at Sarchix.com and it will post on the 24th!

My little guy is just going to LOVE this!

Anonymous said...

Right then, I'm a technodiv but I'm getting this up on my dining room wall for my birthday party (I'll be 40 - stuff the kids!) for a bit of fun! Thank you so much for making it look easy and yep, I got the Minder reference ; )

Marcel said...

Excellent!! I've fancied doing this for ages but lacked the gumption to source that kinda quantity of glow-in-the-dark paint. $8 a pot seems great... I've got a TINY little pot of modelers' g-i-t-d paint and that was probably just as much (!) so I never gave it much serious thought.

I love it! And I love the pics you've posted. I'd been wondering about the flash trick and wondered if it would do the biz. What fun!

Thanks for sharing!


N said...

Awesome! Does the room need to be completely dark for this to work, or is a little ambient (nighttime) light OK? Also, since you used camera flash, it seems that it works with just regular (not UV) light, what about using regular LED flashlights?

666 said...

hey nice article i am checking it once in while.
here is some cheepass paint i found.
8 oz for 20 $ circa

Alicia said...

This is so neat can't wait to show the Hubby and maybe attempt this! Thanks for sharing

PaulBo said...


Regular LEDs/flashlights will work as well. I like the UV ones as it makes the effect of writing more magical since human eyes can't detect UV light (so you only see a little bit of purple light coming out of the flashlight, but the paint glows really brightly).

I mentioned some LED keychains later on in the post; they are bright white and work really well, but they tend to overpower the glow from the wall until they're turned off. The bonus is that you don't have to make them :) I saw loads of different kinds on Amazon and on eBay.

N said...

Aren't UV LED lights dangerous, esp with kids, who would have no qualms about looking into it until they burn their retina off?

PaulBo said...


All bright light is dangerous, but you're right the UV ones are more so because it's not as obvious how much light your retina is receiving. We didn't let our kids use the UV flashlights unsupervised and we told them about the dangers before letting them loose. I'll update the main post with a warning.

Sal-my-gal said...

This is just about the coolest thing ever. I'm dying to do this in the basement for my kids.

Question: would black lights work? Like the ones you buy at Halloween? Or are those UV lights? I'm so low tech!

Unknown said...

So fun!Thanks for posting this great idea.

Unknown said...

This is super cool--this will be at Bucketworks!

Unknown said...

Coolness! Finally got a good reason to use that old can of crayola gitd latex paint before it goes bad.

BTW, you can get cheap UV LED keychains for $.50 ea at

and twice the cost, but supposedly brighter:

and how cool would a UV LASER look?!

(you'll shoot your eye out, kid...seriously, you will...)

Dot said...

Very cool. I'll be linking today on dabbled.org!

thanks for sharing :)

Unknown said...

Anybody ever have one of these as a kids?


Anonymous said...

This is beautiful!
Can anyone who has attempted this post links to a video?

Again, thanks so much for sharing!

Maza said...

Awesome!!! Spooky yet cool. I'll vote this for 'DIY of the month'.

Anonymous said...

so if i paint a wall in my living room in front of a window...will the wall be glowing during the night because of being exposed to the sun all day...or would it glow at night when i turn of the ceiling light in the room (because it was exposed to the light from the ceiling light)?

Kevin Fodor said...

Thanks for the post. This was such a great idea! If anyone is interested here is a link to my experiments with Glow-in-the-Dark paint. http://sites.google.com/site/kfodorprojects/home/woodworking-projects-1/glow-in-the-dark-table-top

PaulBo said...

Hey Kevin, thanks for sharing!

It's great to see other people having a go as well & I love the table idea. Very nicely done!

Carolina Nightingale said...

Coolest. Dad. EVER.

Anonymous said...

what about getting a spare mirror (the ones with the back coating work best) and then getting a CNC machine to cut away the coating.
Then paint the dots with GITD paint and overcoat with a suitable weatherproofing.

Should work well as a nightlight while acting as a mirror during the day as the tiny spots coated with nearly-white paint can barely be seen.


Rhonda said...

Can you please tell me where to get the paint to make the shadow wall? Thanks!

PaulBo said...


I got my pot of paint from HomeDepot. You can get them from quite a few places. Here's an Amazon link to the same product: http://www.amazon.com/Rust-Oleum-214945-Glow-Dark-7-Ounce/dp/B000FBMRAK/ref=sr_1_2?ie=UTF8&qid=1290200674&sr=8-2

PaulBo said...

And here's an actual 'clickable' link for the cut-and-paste phobics.

Rust-Oleum Glow in the Dark paint

Daisy said...

Thanks for posting this. We now have a section of glow in the dark hallway, thanks to your inspiration.

Anonymous said...

awesome thanks for sharing.I have a question if you use a black light or purple light on the background will it ruin the effect of the pictures being made by the flash lights the being and might the entire wall glow or it has no effect on the wall.my daughter has a glow room with black lights but I don't know if I can incorporate a wall like this in her room. thank you and I understand if you haven't tried it and don't have the answer

PaulBo said...


I think that the black light will make the wall have a continuous, low-level, glow. But that you'll still get some effect out of using the flash - it just won't be as pronounced.

You could try painting a bit of scrap wood with the glow in the dark paint and putting it in your daughters room to see how much the black light affects it.

Anonymous said...

this is superb.

London Accountants Lady said...

Wow, these look like hours of fun! Thanks for sharing, my kids would love these!