Zuzanna Szozda
Abstract
Making their first appearance in the 1980s, strong rare earth permanent magnets have since been put to multifarious uses, which has been in evidence in not only technology but also many walks of life, including conservation and exposition of effectively all types of works of art (Braun T. 2001, Etre K. et al. 2014, Monjeau N. 2015, Taira K. 2011)). Such devices are characterized by remarkably high levels of magnetic energy density (reaching orders of magnitude as high as 500 kJ/m3, henceforth displaying very strong forces of attraction (exceeding kN) when interacting with ferromagnetics, such as iron or other magnets. As for conservation (Sterp Moga, E. 2019) as well as mounting systems for museums and cultural institutions (Spicer G. 2019), magnets are in extensive use. Their accumulation of high levels of energy makes for stable holding-strength profile in contact with ferromagnetic surfaces – a strong asset in conservation and exposition.
Characteristically, each magnet comprises two oppositely charged magnetic poles. In the case of strong magnets, these poles and the spaces surrounding them are centers of potent magnetic fields H. The creation of a mechanical force between a magnet and another ferromagnetic object is conditioned on the reverse magnetization of the ferromagnetic: a given magnet’s N and S poles are cross-matched with S and N poles, respectively, which leads to the attractive behavior typical of any two magnets. The forces of mutual attraction between magnets and iron elements reach significant values, which is an advantage, albeit entailing complicated separation. In the cases under consideration, we must reckon with limited control over objects’ relative positioning, which is unstable and unpredictable. There is also another issue, whose salience used to be overlooked before 2020 (Szozda, Z. 2020, Szozda, Z. 2021), namely the interaction between magnetic fields and layers of paint or otherwise (e. g. graphite). This phenomenon has to be taken into consideration in all situations involving exposure to magnetic fields. Such a necessity arises from the fact that the ferromagnetic, paramagnetic, or diamagnetic properties of various substances lead to attraction or repulsion by a magnetic field.
So far, strong magnets used in conservation-related or magnetic-mounting practice have predominantly been in the form of either slim-coin or cube-shaped magnets, tightly pressing the canvas to another magnet or a ferromagnetic surface. But the removal of such magnets may entail some difficulty in separating them, as well as constituting the hazard of some unpredictable damage.
This paper undertakes to present a magnetic holder with pressure adjustment, which possesses the fundamental advantage of smooth attachment to ferromagnetic surfaces. Such a property opens up horizons for new advancements (e. g. an auxiliary stretcher or a stretcher with active magnets embedded in the design), as well as new magnetic mounting solutions for museums and cultural institutions. The primary objective of such a process of innovation focuses on new non-invasive methods, ultimately envisioning future abandonment of nails, staples, or buckles.