Components – the magnets

One of the key elements to reducing heatloss using thermal blinds is to get a good edge seal between the blind and the frame when they are down. This is achieved using high-performance magnets which are sealed within the blind along the outer edges. Each ‘internal’ magnet is then paired with a self-adhesive magnet attached to the window frame, which ‘click’ tightly together when the blind is lowered. They are described by the manufacturer as “Ultra High Performance Neodymium Magnets” – the most powerful permanent magnets known. They are supplied in nickel finish but can be painted on site (we’ve used Humbrol enamels) to match your frame.

We use 10mm diameter N42 Neodymium Magnets. The NORTH pole is on the showing magnetic face and the SOUTH pole is on the face covered in adhesive. These Magnets are plated with 3 layers of protective coatings – Nickel + Copper + Nickel (Ni-Cu-Ni). More technical details are below;

thermal roman blind

magnets are 10mm diameter & just 1mm thick

Magnetic Face: 10mm dia
Thickness: 1mm
Grade: N42
Plating: Ni-Cu-Ni ( Nickel )
Material: NdFeB ( Neodymium )
Performance (Gauss): 1200
Vertical Pull (Kg): 0.45
Slide Resistance (Kg): 0.09
Max Temp (degrees C): 50
Fixing: 3M Self Adhesive

Component sample showing magnets with 3M backing sheet on left, loose on right with white painted magnet at top

The magnets have approximately 1200 Gauss on each face. Each magnet can support a steel weight of up to 0.45kg vertically from the magnetic face when in flush contact with a mild steel surface of equal thickness to the magnet. Each magnet can also support up to 0.09kgs in a sheer position before beginning to slide down a steel surface under the same conditions. These magnets can be fixed in place using 3M Self Adhesive and have a maximum operating temperature of 50 degrees C.

For a typical blind of four folds there are ten magnets down each side, and 20 supplied for the frame to match these internal magnets, so 40 in total. The blinds would probably work just as well with half this number – the red sample blind can be held horizontally & the blind still holds on to the frame!

thermal roman blind

The magnets can be painted to match the frame

Neodymium magnets are the strongest permanent magnets known – Nd2Fe14B. A neodymium magnet of a few grams can lift a thousand times its own weight. It is heavily used in the electric motors of hybrid automobiles and in the electricity generators of commercial wind turbines.

A neodymium magnet (also known as NdFeB, NIB, or Neo magnet), the most widely-used type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. Developed in 1982 by General Motors and Sumitomo Special Metals. They have replaced other types of magnet in the many applications in modern products that require strong permanent magnets, such as motors in cordless tools, hard disk drives, and magnetic fasteners.

The electric motors of each Toyota Prius require 1 kilogram (2.2 pounds) of neodymium. You can read more about neodymium on wikipedia here. Neodymium magnets contain around 25% Neodymium. 98% of the world’s stock of Neodymium is in China. The prices have been volatile recently but appear to be settling with stringent government policies.

Neodymium prices

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