Paint Pulse is a project which seeks to build upon the water marbling crafts of Ebru and Suminagashi with digital behavioral additions. The idea is to design intricate, flowing patterns of paint directly on the surface of water which you can capture on the surface of paper. Expert crafters can hold an intricate mastery over the art and produce incredible results. Our goal was to add additional digital elements to the craft which would afford new means of expression without fundamentally altering the interaction. Thus experts would be able to retain their mastery while exploring new possibilities for the art.

This was made as part of the digital craft research we do in our project studio as part of the Digital World and Image Group by Colton Spross, Andrew Quitmeyer, and Adam Rafinski. In our lab we explore modes of digital intervention in performance, space, and craft in order to create novel interactions between people and their environments.

This thorough instructable will give you the knowledge necessary to make your own digital ebru art-studio, and will as well teach you many different skills for rapid prototyping and physical computing.
Things you will get to learn in this instructable include:

Make cheap, powerful electromagnets
How to make magnetic, floating paint
How to salvage a thin, gorgeous backlight
How to vacuum-form your own paint-resistant tray
Programming Arduinos connected to H-Bridges (Build your own motor controllers for the electromagnets)
Hack ethernet jacks and cables for routing numerous signals over long, hard-wired distances

Step 1: Materials

Paint

Suminagashi - After a whole bunch of experimentation, the easiest to use colors that we have discovered are: Japanese Suminagashi marbling inks
- You can use just regular water, and regular paper and the inks float and absorb readily and easily!
Other Inks
- Ebru - formulated after the traditional Ebru style of painting, need the inks to float in the special Methocel solution instead of just water. These are much trickier to get working!
- Food coloring - floats well, but when you dip it in the water, it doesn't bond to the paper, and just runs off! Annoying!

Ferrofluid

FerroTec EFH1 is the best I have found, it's is a special mixture that if put in a correct substrate, you can get really good display that doesn't adhere to the glass (like in these cells)
You can also find other ferrofluid online for a little cheaper, but note that they all behave differently!

Painting Tray

Pyrex Baking Tray $16
- Since you are working with Ferrofluid, you need a container that is preferabbly clear (so it can be backlit), and won't let the ferrofluid stain it dark. You can just use a large pyrex baking container, but not ordinary plastic trays because the Ferrofluid will permanently stain it.
PET-G Vacuum Formed into a tray 24"X24" $16
- It was really hard to find a large tray made of glass, (the only ones we could find were for auto-claving biochemical stuff and cost around 400 dollars). So instead we built our custom tray from a special type of plastic called PET-G

Dipping Buttons

Sensing and Actuation

Arduino Uno (or whatever you are comfortable with, the Uno has just BARELY enough ports to do this project)
Breadboard
Wires

Electromagnetic Stylus and Rake

Nails (Colton - what are the dimensions)
LED's
10k Resistors
Electromagnetic Wire
Electrical Tape
Stuffing (foam or cotton, non-combustible/flamable)
H-Bridge Chips TI SN754410 $2
Ethernet Jacks x4 (snap open a home depot coupler to get 2 jacks for 2 dollars instead of 1 jack for ~7 dollars at radioshack)
Ethernet Cable (14")

Tools

Hot Glue Gun
Soldering Iron
Solder
Laser Cutter (Optional)
Vacuum Former (optional)
LDF (for tray, optional)
Table Saw (for tray, optional)
3D Printer (optional)
Ceiling with rails to hang the connections, or something else that can hang over the paint area to hold the cables

Paper

Water color paper works nice
Some Ebru techniques need paper that's been treated with alum, these Suminagashi inks that we found shouldn't need any treatment for the paper
Computer paper has been working fine for us (though the colors seem less brilliant on some paper stocks than others)

Step 2: Background Experimentation

To figure out how we were going to implment this concept, we had to do a ton of background experimentation which can be fun and tedious!

This is all based off various techniques of paper marbling (http://en.wikipedia.org/wiki/Paper_marbling) that go back centuries. Paper marbling. Basically all the setups contain 3 main items:

The inks - What you are making your cool designs with
The liquid - what your inks are floating in
The paper - what you stick your inks onto to save your design

The hard part about figuring out a good combination of ink, liquid, and paper is that there are tons of interlocking variables that change the way that the surface of the liquid interacts with the inks and how well the results will stick to the paper.

Various Substance Combinations
We've messed around with milk, nail polish (many different types!), acrylic paint, oil paint, mineral oil, motor oil, lemon juice, metamucil, alum, half and half, soy milk, coconut milk, DI water, salt water.

Step 3: Make Electromagnets

We found it difficult to purchase pre-made electromagnets. They are either very large and expensive, or about the right size and expensive.

We opted to make our own. Really this could probably be its own mini-instructable, and I learned things that I didn't think I would. At first we were like, "oh electromagnets? that's a super easy thing you learn to do in grade school!" But then we found out it can be kind of a pain if you don't know what you are doing. Why? Two main reasons:

Getting decent magnetic performance requires lots of nice wraps with a very skinny wire
If you don't wrap your magnet correctly, you can end up with a huge mess of tangled wire

Our technique worked as follows.

First, get some nice, 4 inch Iron nails. Also get your electromagnet wire.

Jam the sharp end of the nail into a drillpress (or handdrill, if that's all you have). Tighten the nail firmly into place. Set your drill to rotate as slowly as you can (unless you are really good).

Tape one end of the wire around one end of the electromagnet Leave some extra hanging out (this will be one electrode for the magnet), but MAKE SURE to tape this extra wire into a nice little bundle. If you don't collect it up nicely, it will tend to get sucked into the big coil of wire and disappear and make your magnet useless.

With one of the wire firmly connected to the nail, and the spool in your hands, turn on the drill.
You will want to slowly and evenly coil the wire around the rotating nail. Don't try to lead the direction that it spools, it will actually coil nicely all by itself without extra help if you just relax. Standing further away from the drill actually helps a lot too!

When you near one end of the nail, give the spool a tiny tug to reverse the coiling direction and make it coil over the other way.

The tighter your coils, the more wraps you have, and the thinner and less insulated your wires are, the stronger your magnet will be.

We wrapped ours about 8 layers deep (4 times up and down). You can probably go a lot more! You may have even better techniques for wrapping, or a better idea of the electromagnetism stuff behind it all.

When you finish, I try to come back to the same end where I started, and tape some more electrical tape to the end connected to the spool. Leave plenty of extra dangling wire and snip it from the spool. If you run current from one electrode to the other now, the magnetism should be easily felt!

Step 4: 3D Print Stylus and Rake

The electromagnets you make are going to get quite hot. So, in order to keep your hands from getting too toasty, as well as maintaining a comfortable shape with which to perform your artistry, it can be nice to print your own custom holders.

Luckily for you, we already created the 3D files!

Download them here: http://andy.dorkfort.com/code/ebru_models.zip

Step 5: Vacuum Form the Painting Tray

Ferrofluid is a messy substance. It will pretty much turn anything it touches permanently brown or black. We wanted our tray that we painted in to look nice, so we couldn't use an ordinary plastic one. Acrylic and lots of other plastics just absorb the oily ferrofluid and stain readily. It can wash off glass pretty easily, so one simple solution is just to use a pyrex baking dish that is large enough to dip your paper into.

We needed a bigger tray, and we didn't want one that looked like just a baking dish, so we did some experimentation with lots of different plastics and found one, PET-G, that the ferrofluid rubbed off of quite easily! I took the big, 24x24 sheet, and cut it to 18x18 to fit in our vacuum former. I also had to make a mold. I took LDF, and used a table saw to chop it into pieces that I hot-glued into a 16x16 inch box.

We never vacuum formed the PET-G before, and it doesn't heat up as easily as some plastics. Thus the edges did not get that hot, and you can see that the sides made a weird wrinkly zone. The cure for this would be another sheet, and to make the box a tiny bit smaller

Step 6: Laser Cut Arduino + Breadboard Holder

In order to keep your setup looking a bit tidier, you can lazercut a simple holder to keep your breadboard and arduino together. (This is like the poor man's custom PCB).

Also keep in mind, it is handy make extra fun vector images to slice up the insides of any large peices of acrylic that you cut out, in order to have more fun things and be less wasteful. For example, in the space where I cut out the room for the breadboard, I made a Stencil shaped like a silky anteater which I am turning into a necklace for my wife!

You can download the stencils I used here:
http://dwig.lmc.gatech.edu/projects/Ebru/downloads/Arduino_and_PaintJarHolder.ai

Step 7: Build the Buttons: Laser Cutting

Our electromagnetic styluses can pulse in different patterns. We built an interaction methology which tries to simulate the familiar motions of the ebru master dipping his or her stylus into a paint jar. Instead of different colors, however, we have little buttons that you can dip your stylus in to select new behaviors for the electromagnets.

The way it works is that each of the nails, aside from having a wire filled with current wrapping around it, also has an electrode supplying 5 volts directly to the nail. Inside each jar of water we have attached a sensor going to a resistor and one of the analog inputs on the arduino (basic moisture sensor circuit). When we dip the stylus or rake into the cup it moves the registered voltage past a threshold and triggers the new behavior to start!

Step 8: Create the Backlight

We want bright even lighting to help the water-painting artists better see their designs. We also need this light-source to be thin enough to fit under the painting tray. Luckily LCD monitor manufacturers have been working on the problem of thin, bright, even lighting for quite some time!

For our backlight we will be dismantling some old, defunct, LCD computer monitors and harvesting their nice backlights.

(NOTE 1: These things use a high voltage! You are quite safe if you don't do really stupid things (like touch all the inner electronics and capacitors when the thing is turned on). Take caution when ripping them apart and handling. I had a big ( well, .5 inch) arc of lighting zap out of the backlight power supply when I had it on and was probing it with a multimeter! It was pretty cool!)

(NOTE 2: In case Note 1 scared you, You are probably more likely to cut your hand open on all the sharp inside parts than get horribly electrocuted, just keep your head about you, and your fingers safe!)

Step 9: Program Your Arduino

Here's sample code that we used. Just download what we have from Github and upload the code into your arduino. If you have things wired up (and we supplied you with all the correct information) everything should run! We had a quick add-on where we also hooked up the input of the http://pulsesensor.com/ to our system at the last minute so that isn't as documented, but you'll see bits of code where it goes in!

https://github.com/quitmeyer/MagnetRakeWithPulse

Step 10: Wiring

There's a lot of components that either send signals to control a movement (like the switching magnets for the stylus), display indication lights, or sense connectivity. We put together a little wiring diagram for you guys in fritzing to help try to understand what we had going on.

The full file is available here:
http://dwig.lmc.gatech.edu/projects/Ebru/downloads/PaintPulse2.fzz

For another note, all of our devices are hard-wired. In the future, it might be nice to integrate some wireless connections in the stylus and comb, but for this prototype we tried to keep it simpler. One handy thing we discovered is that instead of trying to send 10 different wires running in parrallel from the breadboard, up to the ceiling and into the stylus and comb, and having to figure out how to keep track of these wires ourselves, we came up with the idea to hack ethernet jacks.
Ethernet cable (CAT-5, RJ45 connectors) are usually just 8 wires running in parallel over really long distances. They also have handy snap on and off connectors.

If you try to buy just the jack, they get a little pricey (about 7-10 bucks EACH). BUT, if you purchase a COUPLER you can just crack it in half and get 2 jacks for only about $2.50 (from home depot)

Step 11: Test, Paint, and Play

Marbling is a fun craft! Once you have the system going, test out different mixtures of ferrofluid,, paint, and substrates (milk is always interesting and fun!). Try dipping different papers, and even three dimensional objects!

I got cheap frames from target and made nice framed pictures and cards for friends over the past holiday! It's easy!