Knob magnet, 25mm diameter, iron

Summary

Limited quantity, once these are sold there are no more.

Material: iron.

Shape: round magnet on wooden knob

Size:

- magnet 25mm X 7mm

- total height including the wooden knob, 35mm

Nice to hold, nice to use, good value for this size.

Strength

How many sheets of paper* will this magnet hold securely onto a fridge door?

Answer: 15

* A4 in size, 90gsm in weight (heavier than standard copy paper). 

Uses for testing

Gold and silver are not magnetic. So when you are presented with dozens of items to test, save time by picking out all the items that are magnetic.

This does NOT mean that there are special magnets for testing gold and silver. If an item is NOT magnetic, it could be any one of hundreds of metals (including gold and silver).

Silver is strongly 'diamagnetic'. If you slide an appropriate magnet down a flat silver surface (e.g. a coin) it will move slowly instead of 'falling off'. Copper is slightly diamagnetic. See our 'magnets for silver testing' - a set of 3 magnet, a sample copper coin and instructions.

Copper is not magnetic, neither is brass (a mixture of copper and zinc) or bronze (a mixture of copper and mostly tin). A magnet is useful because many copper / bronze / brass items are really steel that has been plated and will (in most cases) be very magnetic. As with gold and silver: if an item is magnetic it is not solid copper / bronze / brass.

Samples

Not sure which magnet to buy? We have a bargain sample pack of nine different magnets (both iron and neodymium), click here.