“We bought a stainless steel door handle from a certain supplier, mounted it on a front door and sold it to a client. However, after some time, we’ve received a complaint that the door handle started corroding and the process spread to the front door. Now the client doesn’t want it any more. What can we do and what is the problem?”
Of all materials, stainless steel is the most resistant to corrosion. However, this does not mean that corrosion can never occur. The best expert manufacturers of door handles, who know what they are doing, will do everything possible to not let you walk away with a door handle susceptible to corrosion. They will avoid the following conditions to prevent corrosion:
- low-quality stainless steel;
- combining stainless steel with non-ferrous metals in order to reduce the cost of manufacturing;
- imprecise, careless and inappropriate surface treatment;
- poor choice of stainless steel for demanding environments;
- low-quality coating protection that can even speed up corrosion.
What if the client causes the door handle to corrode? This happens frequently, because care and maintenance of door handles is often unsuitable and awkward, which can lead to surface corrosion.
1. LOW QUALITY STAINLESS STEEL (INOX)
The quality of the door handle begins with the choice of high quality material, procured from the best certified European manufacturers. Even if the material looks good when new, its lack of quality will show after the application of surface treatment. During grinding, small pores can arise, which are the side effects of casting. If the manufacturer is not trained to notice such blemishes, the door handle will begin to corrode.
Why is it important for the material to be certified? Stainless steels are ferrous alloys, which receive their corrosion resistance from chromate (forms a self-protective oxidising layer), nickel (increases corrosion resistance) and molybdenum (increases resistance to pitting corrosion); titanium, niobium, zirconium and tantalum are used as stabilisers. A certificate of stainless steel guarantees the correct ratio of aforementioned elements and the best protection against corrosion, whereas versions that are not certified often lack the necessary chromite content or have unknown elements added. As such, the material is more susceptible to environmental effects.
Certificate of stainless steel guarantees the best protection against corrosion, whereas versions that are not certified often lack the necessary chromite content or have unknown elements added.
2. NON-FERROUS METALS IN THE DOOR HANDLE
Faster manufacturing, simpler processes and lowering prices by using cheaper metals have lead many manufacturers to create a stainless steel tube and fill it up with non-ferrous metals (aluminium, bronze, brass, etc.). They overlook the electrochemical interaction of different metals, which creates a galvanic cell, leading to the corrosion of coloured metals when exposed to the air. Rust then moves to nearby parts (i.e. corrosion of the aluminium door panel), which then travels to the surface. This is why it is important that screws, mounts, tubes and other key materials of the door handle are made of stainless steel.
Damage when corrosion spreads from the door handle to the front door. The manufacturer of the door handle is unknown.
3. INAPPROPRIATE SURFACE TREATMENT
Correct surface treatment is the most important factor in preventing corrosion. Long-term experience in grinding offers manufacturers the necessary insight to identifying the best anti-corrosion grinding method. If the manufacturer is in a rush or does not pay special attention to this, the door handle will soon start to corrode.
Polished door handles are definitely more resistant to corrosion than satinised door handles, even though the latter offer the highest protection against corrosion if taken care of properly.
Correct polishing diminishes the small pores that can result from surface treatments. This improves corrosion resistance and reduces the absorbency of microscopic elements. This is also one of the reasons why such treatment is used in the nautical industry, where the conditions for the durability of metals are very demanding.
Long-term experience in grinding offers manufacturers the necessary insight to identifying the best anti-corrosion grinding method.
4. WRONG CHOICE OF STAINLESS STEEL TYPE
If the house is not near a coast, main road or other aggressive environments, then a standard 304 stainless steel (A2 4301/1.4305) is sufficient.
Problems may occur when a door handle of the same stainless steel type is mounted near the sea or in an area where salty air is prominent. For such environments, 316 stainless steel (A4 1.4404) is more appropriate, since it has a greater anti-corrosion protection. If the door handle is polished and properly maintained, corrosion will not occur.
For demanding environments, 316 stainless steel is more appropriate, since it has a greater anti-corrosion protection.
5. IMPROPER CLEANING AND POOR MAINTENANCE
Incorrect cleaning and poor maintenance are the most common reasons for rapid corrosion. Stainless steel may be very resistant, but it should not be cleaned with abrasive solutions, such as cleaners for glass, ovens, silver, brass, cement stains, or soap concentrates, chlorine cleaners or solutions with hydrochloric acid, etc.
The use of rough brushes with strong bristles, steel wool used for cleaning stubborn stains from dishes, the rough side of a cleaning sponge made of iron or steel fibres is also forbidden.
If the surface of the door handle is damaged and the protective layer compromised, the door handle will start to corrode quickly. This is why regular cleaning and maintenance with a protective coating is of utmost importance. Instructions for cleaning and maintenance of stainless steel door handles.
Incorrect cleaning and poor maintenance are the most common reasons for rapid corrosion.
5.1 POOR PROTECTIVE COATING
The worst coatings can even speed up the corrosion. After performing a salt spray test in which we applied 25 different protective coatings, we made a shocking discovery that only one quarter (25%) of the coatings provided adequate protection. If the door handle manufacturer and the client use one of the remaining 75% of coatings, you will not be happy in the long run.
The quality of 25 protective coatings, tested with a salt spray test:
WHAT DO WE DO AFTER RECEIVING A COMPLAINT?
Talk to the unhappy client about the environment they live in (is the air affected by sea, main roads or set in a salty or humid area) and their maintenance methods. You can also send them the instructions for maintenance and care of stainless steel door handles for a better idea.
Once you have eliminated client fault, you should inform the manufacturer of the door handle or supplier and, if possible, provide the product in question. This is the only way they will be able to give a correct diagnosis and opinion on the reasons behind the corrosion. A good manufacturer will help you resolve the complaint.
You should work with the best verified manufacturers and suppliers, who will maintain the highest level of quality and help you eliminate unnecessary complaints.