Harden Black

Functional/aesthetic treatment for an hard and protected surface

Color: black
Applications: carbon and stainless steels
Properties: hardening, anti-oxidant, blackening

Harden Black is a thermo-chemical treatment aimed at hardening steel obtaining, at the same time, an high corrosion resistance and a reduced friction coefficient


Alternative and more performing than traditional treatments such as nitriding and ferritic nitrocarburizing, resolves the need to raise the hardness of steels whether they are carbon, alloyed and/or tempered. The surface hardness can reach, depending on the type of steel, over 70 Hrc (over 1300 HV1). This allows to the treated part to benefit superior wear-resistance and abrasion-resistance properties compared to those offered by conventional treatments such as nitriding, ferritic nitrocarburizing, etc.


Superior to blacking and phosphating, it is able to protect the steel from corrosion. Depending on the type of steel the treated parts exceed 700 hours of salt spray before the appearance of the first corrosion point: a remarkable result when compared to the performance obtainable through classic blacking and phosphating (which do not provide any surface hardening). The corrosion resistance further increases when combined with a low roughness of surfaces obtainable with Super Fin treatment.


The treated parts obtain self-lubricating properties with a remarkable reduction of the friction coefficient. The smoothness benefits from a significant improvement and can further increase if combined with a low roughness of the surfaces obtainable with Super Fin treatment.

The treatment, penetrating into the material, hardens and blackens the steel giving an attractive black color difficult to reach with burnishing, black zinc plating or phosphating

Blacking phosphating stainless steel


Alternative to phosphating, black zinc plating and blacking, it is able to blacken the steel homogeneously. The treated details will benefit of a bright and resistant black color pleasant to the eye as much as an anodizing (this last, as known, not applicable on steel). The treatment can also be applied on components already blackened.

Nitriding stainless steel

High penetration

It is, for a large part, absorbed by the material: the penetration is variable from a minimum of 0.15 up to a maximum of 1mm. This penetration into the steel avoids the risk of flaking and/or detachment of flakes under mechanical or corrosive stresses as can happen with other treatments. Applied to particular steels, and with appropriate calibration of the process, it is possible to obtain extraordinary results in terms of hardness and depth so it is a valid alternative to cementation.

Reduced thickness

The thickness of the coating is limited to about 0.01 μm; a small thickness compared to other treatments such as blacking, zinc plating and phosphating. This property allows, in most cases, the application of the treatment also net of geometric dimensioning of the components and an easy application also on tolerance parts such as threads, pins, etc.

Harden Black can be applied to any type of steel whether it is carbon, stainless or strongly bonded

Stainless steels compatible

As in the case of blacking, phosphating or nitriding, it is compatible not only with carbon steels but also with all stainless steels, also tempered.

Mechanically performing

Often even without a geometric dimensioning that calculates the thickness of coating, it is also possible to apply it on shafts, compasses, gears and any other mechanical steel part that requires the described peculiarities. However, there are no minimum or maximum dimensions for the parts to be treated.

Unaltered resistance

Its use does not weaken the mechanical details because it allows to obtain a very hard "skin" on the soft heart parts. At the same time, in order to protect the intrinsic strength of steel components, the absolute absence of hydrogen in the process is guaranteed.

The treatment, with reduced environmental impact, allows the achievement of results not obtainable together by blacking, phosphating and nitriding

Suggested applications

→ Vintage car screws (Ferrari, Lamborghini, Porsche, etc.)
→ Supercar and hypercar frame details
→ Pins, shafts, compasses
→ Gears
→ Slide guides
→ Parts of firearms, muzzle brakes, etc
→ Blades, military cutlery, survival, mountain-climbing, etc

Questions to which the treatment answers

→ Which is an alternative and superior treatment to blacking?
→ Which is an alternative and superior treatment to phosphating?
→ Which is an alternative and superior treatment to black zing plating?
→ How to harden steel?
→ How to make the steel corrosion resistant?
→ How to increase the smoothness of steel?
→ How to blacken steel?

Blacking phosphating steel

Nitriding steel

Black zinc plating steel

The synergy between the treatments offered by Precise Technology allows the offer of a service unique in its kind: the possibility of submit the components to two or more treatments in order to follow all the process from beginning to the end and obtain an unsurpassed finished product.

The elements intended for Harden Black can be previously:
— Solvent or ultrasonic cleaned
— Re-pickled from previous treatments (e.g. zinc plating, blacking, nickel plating, etc.)
— Micro shot peened
— Polished or treated with Micro Fin

The Harden Black treated elements can receive other coatings such as:
— MicPol® impregnation
— Graphite coating or other molybdenum disulphide coatings
— Powder coating

Blacking phosphating zinc plating nitriding

Pick-up and delivery

The headquarter of Precise Technology SA is strategically located in Chiasso so that it can easily serve, through an organized logistics network, the whole Swiss territory, the whole Italian territory and, more generally, all Europe. Thanks to the pick-up and delivery service, the company can apply Harden Black treatment (which combines the beneficial properties of blacking, phosphating and nitriding) to corporate and private customers located in Italy, Switzerland and all Europe.

Pick-up and delivery throughout Europe Services for corporate and private customers
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