November 2018

Firstly it should be pointed out that the research, which forms the basis of the new classification, carried out by the Rapporteur (Danish Environmental Protection Agency) was based purely on exposure in those industries that are major users of Nickel, i.e. nickel producing industries and nickel plating industries.

The category 1 carcinogenic classification of certain water soluble nickel compounds is linked only to inhalation (not by ingestion or dermal exposure). This means the issue is only relevant to occupational health in nickel-producing and certain nickel-using industries.

A cocktail of compounds exists in nickel refining situations and therefore the exact role of water soluble nickel compounds such as nickel sulphate or chloride, in terms of their contribution to cancer risk, has been unclear.

The recent risk assessment on Nickel, carried out by The Danish Environmental Protection Agency on which the EU classification is based, found as follows:

Respiratory exposure to nickel sulphate occurs only in an occupational exposure context, by inhalation of aerosols containing nickel sulphate, by definition an aerosol is an assemblage of small particles, solid or liquid, suspended in air.

Aerosols would commonly be created from a tank of liquid by bubbling air through it. As the air bubbles rise to the surface and break, small droplets of the solution are released into the air. Large drops fall back into the tank or deposit on surfaces nearby. Smaller droplets become airborne and drift into the general plant air where the workers can inhale them. Small droplets rapidly lose their water by evaporation, leaving behind solid particles made up of crystals of nickel salts and the other components of the bath. Blackfast 181 is not agitated and therefore should not be capable of producing aerosols.

Even if we assume the blacking process to be similar to electroplating and capable of producing aerosols it must be noted that Nickel Sulphate, in the average plating bath, is generally maintained in the concentration range of 150- 300 g/l. Blackfast 181, as supplied, contains less than 50g/l and diluted to working strength (25%) less than 11g/l.

The data available on groups of nickel species in workrooms indicated that nickel species are not uniform among electroplating shops. Nevertheless an estimate was made for a typical and a worst-case nickel speciation, but the validity of the estimated data remains unknown. TERA (1999) reviewed the toxicology of soluble nickel salts and on basis of the data on occupational exposure provided by NIPERA (1996) it was concluded that the median exposure by inhalation of soluble nickel salts was about 20 µg/m3 in electroplating operations.

We should therefore be able to conclude that Blackfast 181, if capable of producing aerosols, would produce, as an absolute maximum, half the amount of inhalable nickel that a plating bath would i.e. 10µg/m3. This equates to 0.01mg/m3.

Learn more about Nickel Sulphate in the blacking process

Engineering and construction firms have long utilised blacking methods to prevent metal tools and equipment from reflecting light because glare can be hazardous for workers.

A popular blacking process is known as electroplating, which describes the process of submerging an item in a solution containing nickel. However, if inhaled, nickel sulphate is carcinogenic.

Occupational health is a huge concern for all employers in settings where chemicals and machinery pose hazards, and if there are any traces of airborne nickel sulphate in your workplace, you might be breaking the law. Fortunately, there is an easier and better way to blacken metal, and it doesn’t risk contaminating the air that your employees breathe with a dangerous carcinogen.

 

Metal blacking with Blackfast

At Blackfast, we utilise a sophisticated chemical conversion process for blacking steel and iron items, and you’ll only find small traces of nickel sulphate in Blackfast 181, one of our most popular solutions.

More importantly, the nickel sulphate found in our solution doesn’t pose a health risk.

The carcinogen in question is only dangerous if inhaled as an aerosol, which in this context means any air-suspended solid or liquid particles. Usually, an aerosol containing nickel sulphate is produced by pumping air into a plating bath, but our blackening method requires no such treatment.

Furthermore, there is only a small trace of nickel sulphate in Blackfast 181 when compared to the average plating bath, minimising the threat that the carcinogen in question presents to people at your workplace.

 

Current occupational exposure limits for nickel Sulphate are as follows:

 

 

The benefits of metal blacking without nickel sulphate

New paAs described above; the primary reason to avoid nickel sulphate from becoming airborne in your workplace is to prevent related health conditions affecting your workers. However, the benefits of using a blacking solution that doesn’t release harmful levels of nickel sulphate extend far beyond that.

Our blacking solution doesn’t alter the dimensions or weight of your metal items, which is crucial for small objects such as screws and tools. Nickel sulphate in the blacking process has the potential to slightly change the surface of an object, rendering them unsellable or useless. Plus, because our products don’t apply an addition layer of material to an item, it’s one of the most affordable solutions over the long term.

Hydrogen embrittlement occurs when hydrogen atoms or molecules diffuse into the surface of a metal component, compromising its structural integrity. Once beneath the metal’s surface, hydrogen atoms form into molecules and cause the metal to weaken, often resulting in visible cracks. Unfortunately, hydrogen embrittlement can be an unwanted side effect of metal blacking, depending on the method used.

How plating and painting can cause hydrogen embrittlement

When you plate a metal component to change its colour, it’s possible to trap hydrogen atoms on the metal’s surface without any room to escape. Fortunately, if you’re wondering how to prevent the hydrogen embrittlement process when blackening metal, the experts at Blackfast can help.

Because our metal blacking and antiquing solutions don’t require the application of additional materials, we can prevent hydrogen embrittlement. In addition to bolstering the look of metal items, our solutions make them extra resistant to corrosion and deterioration.

Plus, unlike painting and plating, our formulas don’t alter an item’s weight or dimensions, which is crucial in many situations. If you’d like to see how Blackfast 716 and Blackfast 551 work, we’ll gladly arrange a face-to-face demonstration at a time that suits you. Don’t hesitate to contact us if you want a more in-depth introduction to hydrogen embrittlement.

How blackfast helps companies prevent hydrogen embrittlement

We’re making a name for ourselves in the UK and across Europe thanks to having an advanced metal blacking solution that almost eliminates the risk of hydrogen embrittlement. Our products, such as Blackfast 716 and Blackfast 551, provide businesses with the means to submerge components in our unique chemical formula, which blackens the surface of metal by altering its chemical composition rather than plating it in an additional material.

Thanks to our innovative metal blacking solutions, you can prevent hydrogen embrittlement when blackening even soft metals. Plus, hydrogen embrittlement most commonly occurs when components are treated with an acidic solution, but because our solutions are alkaline, the risk of such an issue is minimised. Add this advantage to the fact that our blacking solutions are more affordable, more effective and safer than many conventional methods, and you can see why products such as Blackfast 716 and Blackfast 551 are becoming increasingly popular in many European nations.

The Blackfast process

The cleaner, Blackfast 716, is an alkaline solution and should therefore not be capable of producing hydrogen embrittlement.

The conditioner, Blackfast 551, is acidic (pH 2.5-3) and contains small amounts of phosphoric and hydrofluoric acid (less than 0.1% in the working solution) and immersion time is no more than 2 minutes.

The blacking solution, Blackfast 181, is also acidic (pH 3-3.5) and contains phosphoric acid and potassium bifluoride (less than 1% in the working solution) and immersion time is only 1 minute.

It is concluded that the Blackfast process contains very low amounts of acid and the immersion times are minimal which should mean that the process is unlikely to cause hydrogen embrittlement.

Coating porosity also has an impact on hydrogen concentration. Electroplated coatings are dense enough to “trap” or seal hydrogen in the base material. Once the hydrogen is sealed in the component, it is more likely to produce an embrittlement failure. Mechanical coatings are more porous (less dense). Therefore, any hydrogen in the base material of a mechanically coated component will have a better opportunity to escape.

The Blackfast process is not a dense coating, rather a surface conversion, and it is specifically designed to produce a porous crystal lattice which will allow oils and waxes to be absorbed into it.

The Blackfast process is therefore unlikely to be capable of trapping or sealing hydrogen in the component.