Magnet(ism)Paint

About Magnetism and MagnetPaint

Why some magnets hold up to 20 sheets of A4 copypaper and others, uhm … well … only one. Hardly.

Chapters

  • Magnetism
  • Coat thickness
  • Better magnetism by a smooth surface
  • Magnetic foil: strong magnetism

Magnetism

First of all: MagnetPaint is not magnetic, it is ferromagnetic. Like ordinary iron. This means that magnets will be attracted by it.

In the paint itself is a high dose of special iron powder. This makes the paint heavy, which results in a density of 2.62 (2.62kg / liter).

Although it contains a high dose of iron powder, the magnetic force can not be compared to a full iron plate, like the door of a refrigirator. This is because the amount of iron particles per square centimeter in paint is much less then in the iron plate. This makes the quality of the magnet decisive for the magnetic strength.

Cheap (brown/black) magnets, like give-away magnets, are meant for use on refrigirator doors, and function well with a minimum of magnetic force. There are however also good quality brown/black magnets, but hardly can be recognized as such. That’s why MagPaint advises to use Neodymium magnets, which can be recognized by their steel surface. They are made from the strongest magnetic material.

This can be the difference between a magnet holding only one sheet of A4 copypaper or 20.

wallmagnets-magnetpaint
Magnets used at the office: even a calculator is hung to get more space on the desk (backside with two magnetic stripes). Magnetpaint topcoated with a clear glitterpaint (blue)

Coat thickness

Never use less the 0.5 liter MagnetPaint per square meter or the magnetic force will decrease. 0.5 Liter results in a thickness of approx. 0,7mm, which is ideal for magnets. When using Neodymium magnets extra magnetic force can be obtained by thickening the layer of MagnetPaint. This is because Neodymium goes deep into the paint, while other magnets stay on the surface.

Usually the thickness of 0.7mm is obtained by applying two or three coats of MagnetPaint. HOWEVER … this depends totally on the way you paint and what type of painting tools you use. Some people apply thick coats as others apply hardly any thickness. Also: when you use a lacquer roller, less paint is applied, as when you use a long haired roller. One coat for optimal magnetic results (0.7 – 1.0 mm) can be obtained by spraying with the airless technique. Please look at ‘Application’ for more information.

Better magnetism by a smooth surface

Magnets work best when they are the closest to iron. A very smooth painted surface therefor results in a stronger magnetic force, then with a rougher painted surface. With a rougher finish, small gaps directly under the magnet weaken the magnetic strength, because there are no iron particles.

There is only one thing that contradicts this: when the surface is finished with a very smooth/slippery paint, like a dry-erase paint, the grip of the magnets can be decreased. This is why always Neodymium (steel) magnets should be used on slippery surfaces.

Magnetic foil: strong magnetism

The most impressive use of MagnetPaint is in combination with magnetyic foil: really heavy or big things can be hung to the paint. Magnetic foil makes optimal use of the surface. All over the surface of the foil magnetism is used and thanks to the large surface, slipping off the surface is pratically impossible.

However, breaking away from the surface goes very easy and determines the point that objects fall off.

Examples: