DIY magnetic ink
I used to buy magnetic paint, but I wasn’t very happy with its strength, consistency and color, so Nick Vermeer and I decided to make our own. More often than not, things turn out to be more complicated than they appear, but in this case it was the other way around!
Nick sourced fine magnetite powder and we then experimented with several media. The one that seemed to offer the best combination of strength, appearance and consistency was the glossy acrylic medium. Here’s the super simple process for making your own magnetic paint:
Ingredients: magnetite powder + acrylic medium (see suppliers below)
1) The magnetite powder is really fine so wear a dust mask and goggles.
2) Mix 2 parts acrylic medium with 1 part magnetite powder by volume (we use measuring spoons).
3) Stir very well and get rid of all the clumps. You can do this by hand or use a vortex mixer (Cathal Garvey shows how to make your own on this video).
4) Apply 2 or 3 coats of the mix, depending on how strong you want it to be. On the video above I used 3 thin coats. Once it’s dry you can paint over it with regular paint or cover it with some thin material like paper.
You can also try other solutions, it’ll work with almost anything, though the proportions will vary depending on the consistency of the medium. One approach is to start with the amount of magnetite powder you want to use and add the medium to it little by little until it has the desired consistency.
Suppliers
Chemical Store (magnetite powder)
Utrecht (acrylic medium)
[...] Mota and Nick Vermeer experimented with magnetic ink: I used to buy magnetic paint, but I wasn’t very happy with its strength, consistency and color, [...]
can it be conductive on the magnetite powder? or any idea how I can make conductive ink?
Too bad the video isn’t working. Really wanted to see this.
[...] Mota and Nick Vermeer experimented with magnetic ink: I used to buy magnetic paint, but I wasn’t very happy with its strength, consistency and color, [...]
Magnetite is not conductive (sadly), but you can get the properties of both by first applying one or more layers of magnetic ink, letting it dry completely, and then covering it with a layer of conductive ink.
Nick Vermeer has been working on a DIY formula for conductive ink. You can see one of his progress reports here: http://openmaterials.org/2012/05/18/more-diy-conductive-inks/
Jordan Bunker also arrived at a DIY method, but the current formula doesn’t work on porous materials: http://openmaterials.org/2012/03/15/hackerspace-made-conductive-ink/
For conductivity, just throw some graphite in the mix. If you can make paper circuits with simple pencil lead, then it should be simple enough to get the same effect.
Thanks for the suggestion Tristan, but unfortunately it doesn’t work that way. For a material to be conductive the conductive particles in it need to physically touch so electricity can flow from one to the other. This works with pencil lead because there is nothing else in the mix. In this case, the acrylic medium and magnetite would be in the way. If we added a lot of graphite we’d probably get something, but it would still be very, very resistive. This is the biggest challenge in making DIY conductive paint: finding a binder and process that actually pushes the conductive particles together instead of insulating them.
I was quite surprised to read that people are trying to formulate conductive ink. “Gall Ink” as used by the Venerable Bede, made from the parasitic galls found on oak trees is quite conductive on paper once the carrier has dried of. The galls are full of Iron. After processing, the ink is basically a suspension of Iron Oxide. Most modern versions of the ink use Gum Arabic as a binder, using less in the ink decreases the resistance; using more increases it. The Saxons however used bone as a binder which is much less resistive. Ink’s made from the old “Lamp Black” method are also conductive.
regards Ricky
so if you add copper powder to the acrylic paint , you need a binder that will bridge the insulated gap.
Peter: exactly, let us know if you have any ideas for a cheap, easy to acquire conductive binder.
I am impressed and your philosophy as outlined in the TED talk touches my heart.
However, for this binder, have you tried the common PVA (Polyvinyl Alcohol) adhesive which is water soluble. I say this because in India household adhesives for pasting paper, books envelopes etc used to be gum arabic. Over the years it has all been fully replaced by PVA.
Regards, best wishes
Well Catarina… if you had a conductive binder there wouldn’t be a need for any additional powder :D maybe some soluble ink for colour… but that too could impair the conductivity…
Haha, sort of :) What I had in mind was something like electrolyte gel – the graphite would improve conductivity and add color to actually make it look more like a paint. But that’s not what I think commercial solutions use – it’s probably an acrylic that contracts once dry, improving contact between the conductive particles.
Isn’t this iron ink rather than magnetic ink? I tried making this and the ink wouldn’t stick to paper clips, only magnets.
It seems that the magnetic attraction is there, but very weak. The gloss I got seems to demand two parts magnetite for every part of gloss.
Hi Burhan. The material is magnetic and can be magnetized, but it is not a permanent magnet. You can read more about this here: http://en.wikipedia.org/wiki/Magnet#Magnetic_materials
The ratio can vary a lot with depending on the medium. I usually start with the amount of magnetite I want to use and slowly add medium to it until it has the desired consistency. And once you get there, it’s advisable to use 2, 3 or more coats of the paint as that will make it stronger.
One could also use Barium Ferrite powder for a magnetizable ink. Exposing it to a high magnetic field such as from a rare earth magnet will permanently magnetize the ferrite. For conductivity, if the solids loading of conductive METAL powder Cu, Fe, Ag, etc. is high enough, the particles will be touching and conductive. They make a Silver based conductive paint for grounding samples in electron microscopy.