Why magnetic snaps cannot pass salt spray test and needle detection test

Why magnetic snaps cannot pass salt spray test and needle detection test

Magnetic snaps are used for closures in different accessories. They are metal buttons used in purses, handbags, packaging closures, leather clasps, and other accessories. Richarms metal Accessories Expert is one of the biggest manufacturers and suppliers of magnetic snaps used in clothing, leather, wallets, notebooks, and bracelets.

Salt spray or saltwater testing is commonly used in corrosion testing. Saltwater testing is one of the most commonly used testing methods to check if a metal coating can hold out against any atmospheric corrosion. Salt spray testing is done in laboratories and commonly on metal fittings. Magnetic snaps and snap buttons require a rivet to support closure. 

The salt spray tests can take place and last from 8 hours to 3,000 hours more or less depending on special cases. The test requires a 5% solution of sodium chloride with a pH between 6.5 and 7.2. Once the magnetic snaps have been subjected to the corrosive environment for the period set, it is inspected to see if the magnetic snap shows rust or other oxides. The magnetic snaps are only accepted when there are no signs of corrosion or rust in any way. Hence, it can withstand different and extreme atmospheric conditions for a very long time.

The Q-FOG is one of the best machines for salt spray testing. Salt spray testing is used as the only corrosion resistance testing method and it is also a component of the ISO 12944-9 which conducts the salt spray testing process similarly as per ASTM B-117.  Salt spray testing is usually done between 24 and 1000 hours according to ASTM B-117 standards.

But unlike the ASTM B-117, which only tests for static salt spray, the ISO 12944-9 is a cyclic test that goes up to 25 weeks of repetition. Starting with panel testing for 72 hours to check for tolerance against UV exposure. Followed by salt spray testing for 72 hours and then freezing the metal for 24 hours. This makes a total of 168 hours per week and 4,200 hours for 25 weeks.

There are several examples of salt spray test results and the hours they take to complete, such as; Black Oxide shows corrosion after 24 to 96 hours. Ruspert coating does not show any traces of rust even after 1000 hours. Hence, it’s safe to say salt spray testing works, but just not on magnetic snaps.



Magnetic snaps use metal fittings that need to be able to withstand the atmosphere outside the laboratory, hence the rigorous tests. Normal snap buttons are tested by a pulling machine; they do not require saltwater testing because they are not magnetic. A rivet is also used in magnetic snaps to support the closure of the accessory; it is used in.

The magnetic snaps can only pass the 24-hour salt-water test and not the back. This is because there are two iron parts assembled on the back of the magnetic snaps, which are electroplated after being assembled by an automatic machine. Due to this, there are several gaps in assembling. The assembly position and the position of the gap cannot be electroplated. When the water droplets from the salt spray test run into the gap in the iron embryo. The iron will begin to rust and slowly extend to the periphery. The back generally only passes the 6-hour salt spray test.

The magnetic snaps, metal fittings, rivets, and snap buttons cannot pass the needle detection test because of the magnetic and metallic properties of these accessories. The needle detector will respond to metal powder, metallic debris, metallic impurities, and certain chemical substances in these accessories. Most needle detectors are very accurate in detecting any metallic substances and since the magnetic snap is metallic and magnetic, it cannot pass the needle test.


Needle detection is done by garment manufacturers to check if there are any broken needles or any other properties in a garment that may cause harm to the consumer. For garments with magnetic snaps, they are hard to pass the needle detection test because they have rivets and metal fittings which can alter the test process.

Although, there are different types of detectors, some of them are not highly sensitive enough to detect magnetic snaps when garments are put in a different position. Currently, manufacturers have found a solution to separate the plate magnet from the metal detector for the test to run without any problems but it is still not enough to ensure the safety of consumers.

The needle detection test reacts to many different scenarios such as accessories with a number of metal trimmings such as fasteners, snap buttons, rivets. And even if every single item conforms to the needle detection standard. The magnetic snaps are manufactured out of metals like ferrum, nickel, and cobalt. Hence, they require surface treatment for ferromagnetic substances.

Since the needle detector is used in detecting any metallic properties and magnetic snaps are metallic in nature and magnetic. The testing is bound to fail. The needle detector will detect the magnetic snaps in garments and fail to detect any broken needles. This will in turn cause harm to consumers who will use the products.

For needle detector testing to work magnets need to return to a magnetic neutral state. This refers to demagnetization which involves adding and subtracting operations in magnets objects. The needle detector checks for magnetic components of cobalt, iron, and nickel rather than checking the magnetic snaps. Hence, needle detection tests will never work for magnetic snaps.

Demagnetization cannot change the magnetic snaps, but the passing of the needle detection test can be achieved. Only the raw materials in the magnetic snaps can be replaced with non-magnetic forces such as copper, zinc alloy, or aluminum, which are known as non-ferromagnetic metals.

Thus, when conducting needle detector tests on various products and magnetic snaps, the tester must keep in mind that the needle detector is used for testing products without magnetic elements, otherwise, the test will be incoherent and meaningless.