How Does Magnet Paper Work?

Magnet paper (or magnetic paper) is a thin, flexible laminate that bonds a printable paper surface to a magnetic backing. The backing is a rubber or plastic layer packed with magnetized strontium ferrite powder, so the sheet sticks to steel surfaces like a fridge door. Paper itself is not magnetic; the magnetism comes entirely from that backing. The sheets run through most inkjet printers for cheap, custom magnets.

If you’ve been looking for a new way to spice up your classroom whiteboard lectures, want to promote an event you’re hosting in a creative way, or create an emergency phone number list that won’t fall off the fridge, you may want to look into magnet paper. Despite the less than creative name, magnet paper is a clever and useful product that can be used with many common inkjet printers.

What Is Magnet Paper?

Magnet paper is a combination of magnetized rubber and paper, and typically comes in letter-size (8.5 x 11 in) or A4 (210 x 297 mm) sheets for easy printing. This type of paper is very popular for short-term advertising and marketing efforts, instant magnet photos for the fridge, educational tools, business cards and so much more.

The paper itself isn't magnetic at all. The sheet becomes magnetized because the elastic rubber or plastic on the back is packed with magnetized strontium ferrite powder, the same hard ferrite used in cheap ceramic magnets. Each grain of powder is a tiny permanent magnet, so millions of them bonded into a flexible binder add up to one workable magnetic sheet. The more magnetic powder packed in, the stronger the pull, but a stronger sheet is also stiffer and thicker, which limits the printers that can feed it.

These sheets only grip ferromagnetic surfaces, meaning steel or iron, such as a refrigerator door, a filing cabinet or a whiteboard with a steel core. They will not stick to non-magnetic metals like aluminum, brass or copper. The material is very pliable and easy to cut with a razor blade or scissors, so you can create a number of different magnets, such as uniquely personalized name tags, without buying them in bulk from a traditional manufacturer of custom magnets.

Magnet paper can be matte or glossy, and is ideal for high-quality photos. The sheets are thin, usually around 0.3 millimeters (about 12 mil, or 0.012 in) thick, and are fed through the printer one at a time. While many companies sell magnet paper in the same letter or A4 size as normal printer paper, there are other forms, such as larger rolls for large-format printing. Feed works best on printers with a straight or near-straight paper path, since a tight U-turn path raises the odds of a jam. You should always print on the highest possible quality to get the best results for your magnets.

Disadvantages To Magnet Paper

While this is a very cool product that can lead to some awesome merchandise, there are some clear downsides. Most magnet paper is meant for inkjet printers only, and for a good reason. A laser printer fixes toner by passing the sheet through a fuser that runs near 200 degrees Celsius (about 400 degrees Fahrenheit), but the rubber binder in the magnetic layer starts to soften and warp above roughly 70 to 80 degrees Celsius (160 to 175 degrees Fahrenheit). Inkjet printers stay cool and spray ink straight onto the surface, so they sidestep that problem. (A few specialty sheets are sold as laser-safe, so always check the label before you load one.)

If the printing tray doesn’t push out flat, it could cause deformations in the image being printed, and the finished sheet shouldn’t be left exposed to water or harsh sunlight. The ferrite powder itself won’t rust or lose its magnetism, but prolonged UV exposure breaks down the rubber binder, leaving it brittle and prone to curling or cracking, which weakens how flat and firmly the sheet sits against the surface.

Furthermore, in terms of convenience, using magnet paper on any sort of large print order isn’t very efficient. The sheets can only be loaded into the printer one at a time, or else the sheets would stick together and load improperly.

Printers also tend to heat up when used for extended periods, which adds to the risk of using an old printer. Some types of printers use electromagnets to operate the machinery, and this can lead to printing disasters with magnetized paper. Similarly, ferrous materials in the printer itself may attach to the paper and not let it pass through the machine. Checking your printer and doing your due diligence online before using magnet paper is a wise move.

How Do Magnets Stick To A Fridge?

Here is the part that trips most people up: the magnetized backing does all the work, but the fridge door is not actually a magnet. So why do the two pull together? The answer is that the steel skin of a fridge door is ferromagnetic, the same family of magnetic materials as iron, nickel and cobalt. Inside that steel are countless microscopic regions called magnetic domains, each one a tiny built-in magnet pointing in a random direction. With no magnet nearby, all those domains cancel each other out, so the bare door shows no magnetism at all.

Bring a magnet (or your sheet of magnet paper) close, and its field nudges those domains in the steel into alignment. The door briefly becomes a magnet itself, oriented to attract the one you are holding, and the two snap together. Pull the magnet away and the domains in the steel mostly drift back to their jumbled, cancelled-out state, which is why the fridge does not stay magnetized once your shopping list comes down. The magnetic field of the sheet does not need to grab the paper either; the paper is simply laminated to the magnetic layer, so when the backing locks onto the steel, your printout rides along for free.

Why Does Magnet Paper Only Stick On One Side?

Flip a fridge magnet over and you will notice it only grips on one face. That is not a manufacturing shortcut; it is clever physics. When the magnetic sheet is made, the strontium ferrite powder is set into the binder and then exposed to a magnetic field that alternates in direction along the length of the sheet, locking in a striped pattern of narrow north and south bands rather than one big north pole and one big south pole.

This is a real, named arrangement called a Halbach array, after physicist Klaus Halbach, who developed it at the Lawrence Berkeley National Laboratory in the 1980s to focus particle-accelerator beams. The trick is that a rotating pattern of magnetization reinforces the field on one side of the sheet and cancels it almost to zero on the other. Flat flexible fridge magnets are deliberately built this way, because the one-sided field gives a much firmer grip on a steel surface than a plain, uniformly magnetized sheet of the same weak ferrite would. It also explains a familiar quirk: slide two flexible magnets across each other and you can feel the closely spaced bands bumping in and out of attraction, almost like tiny teeth catching on a comb.

How Do You Print On Magnet Paper?

Once you have the right inkjet sheet loaded, printing on magnet paper is much like printing a premium photo, with a couple of extra settings. In your print dialog, pick the heaviest media or photo-paper option your printer offers and set the highest print quality. That tells the printer to slow down and lay the ink gently onto the coated surface, which matters because the glossy top coat absorbs ink more slowly than ordinary paper and is prone to smudging if you rush it.

Let each sheet sit for a minute or two after it prints, so the ink can dry before you handle it. Then trim to shape: because the back is just flexible rubber, you can cut clean photos, name tags or business-card magnets with scissors or a craft knife, no special equipment needed. If your printout comes out faint, streaky or off-color, it is almost always the wrong media setting rather than a fault with the paper, so revisit the quality and paper-type options before blaming the sheet.

A Final Word

Whether you are creating funny new fridge magnets for your kids or sprucing up the office with some eye-catching signage, magnet paper can be a quick, inexpensive and fun way to advertise and communicate. While there are a few disadvantages and limitations to this creative medium, it is definitely something that can help you stand out in a crowd of business cards and flyers!