Refrigerator magnet

Magnetic viewing film showing magnetic poles of a refrigerator magnet

Later, a flexible magnet was developed, composed of a high-coercivity ferrimagnetic or ferromagnetic compound (usually barium ferrite) mixed with a plastic binder,[4] extruded as a sheet.

Halbach array polarisation

Unlike most conventional magnets that have distinct north and south poles, most flexible refrigerator magnets are magnetized during manufacture in a sophisticated magnetization pattern called a Halbach array. This construction almost doubles the magnetic field on the refrigerator side and almost zero magnetic field on the other.[5]

This pattern can be impressed on the sheet by rolling a line of powerful cylindrical permanent magnets arranged with alternating magnetic poles.[6] This pattern can be felt by taking two similar (or identical) refrigerator magnets and sliding them against each other with the refrigerator sides facing each other: the magnets will alternately repel and attract as they are moved a few millimeters. The pole-pole distance is on the order of 5 mm, but varies with manufacturer.

Refrigerator Magnets on a board - Private Collection

At one time, the largest verified collection of refrigerator magnets belonged to Louise J. Greenfarb from Henderson, Nevada (suburb of Las Vegas, United States). Her world record was included to the Guinness World Records with 19,300 items as of 1997.[10] According to the British "Book of alternative records", it grew to 29,000 as of February 2002, and later up to over 30,000 items.[11] Over 7,000 magnets from Greenfarb's collection were exhibited at the Guinness Museum in Las Vegas, which has since closed. According to her son, Bryan Greenfarb, as of November 2015 Louise still collects and has around 45,000 plus non-duplicate refrigerator magnets but the Guinness verification process, which can take over 6 plus months, is just too taxing to keep validating the exact number. Louise Greenfarb died December 7, 2019. Her son Bryan Greenfarb is in possession of her over 65,000 non-duplicate refrigerator magnets.

In January 1999, Tony Lloyd, a teacher in Cardiff, Wales, was interviewed by the Channel 4 Television programme Collector's Lot when it was ascertained that he had the largest collection of refrigerator magnets in Europe at that time, over 2000.[12] As of January 2016 he had a collection of over 4500. He was again interviewed by the BBC and ITV during 2017. In February 2018, whilst on holiday in Sri Lanka, his 104th country, Tony's collection surpassed 5,000 magnets.