Did you consider these key questions when selecting your metal cleaning agent?

Richard Starkey, Sales Manager UK, Ireland and Scandinavia, SAFECHEM 

For many high precision industries such as aerospace, automotive or medical technology, industrial parts cleaning is crucial to quality assurance. Insufficiently cleaned parts can affect many subsequent processes such as coating, welding, bonding and assembling.

When deciding for the right cleaning approach, many people instinctively ask: “Which is better – solvent or aqueous?”. The answer is: it depends.

Achieving the cleaning quality required is just one part of the equation. It is equally important to ensure that your parts cleaning process is economically viable, safe and sustainable. Identifying the right cleaning solution would require some critical reflection across the technical, economic, safety and health aspects. Some key questions you should consider include:

  1. What are your cleaning quality requirements?

Different industrial applications necessitate varying degrees of surface energy of the metal surface, which is influenced by filmy contaminations. With nitriding, for example, a higher surface energy is required than with standard coating or assembling. The required surface energy should therefore match the ability of the cleaning agent.

In aqueous cleaning, as soils and contaminations are emulsified and flooded off the surface which remain in the water (unless specific procedures are performed to purify the water), the quality of cleaning will mainly depend on the quality of the rinsing baths, as well as the number of the rinsing baths with demineralized water. The higher the required quality of cleaning, the investment and space requirements for the aqueous systems will increase accordingly.

2. What is the affinity of the cleaning agent to the soils?

Effective cleaning is based on the principle “Equal dissolves equal”. For water-based types of contaminations such as coolant and lubricant emulsions, aqueous cleaning agents are typically the first choice.

When removing mineral oil based, non-polar contaminations, such as machining oils, greases and waxes, solvent will commonly be the preferred cleaning agent.

Above contaminations can be classified as filmy contaminations, which can be dissolved in a suitable cleaning agent. Another important category of contaminations are particles like chips, dust and residues of polishing pastes. These contaminations cannot be dissolved in a cleaning agent. To remove those, sufficient mechanics are required in the cleaning machine to flush off the particle contaminations.

The graphic shows what types of contaminations are best cleaned off by which cleaning agent. To achieve optimal cleaning results, the cleaning agent should be chemically similar to the contaminant.

3. What metal types are you cleaning and how are they configured?

In water-based processes, cleaning agents which can be acidic, neutral or alkaline, are usually matched to specific metal types. Simultaneous cleaning of different metals can therefore be problematic and this can result in compatibility issues and in worst case: corrosion. Solvents in comparison have universal compatibility with metals.

If the component parts are tiny or have complex geometry or small crevices, solvent is often recommended due to its lower surface tension and viscosity which makes it easy to wet into and evaporate out of tight spaces.

4. What is the environmental impact?

The energy consumption in a water-based process can be significant, due to the energy requirement to operate high-pressure pumps; heat the cleaning water; dry the metal parts; as well as treat and purify used water for re-use or disposal. Depending on the cleaning agents, dirts and soils are emulsified and the contaminations diluted in the water. As a result, aqueous baths that are not treated have to be replaced frequently.


Solvent in closed vacuum vapor degreaser can be recycled again and again via the built-in distillation unit. This can significantly increase solvent lifespan and cut down on waste volume. While energy is required to keep the closed cleaning machine under vacuum, this also lowers the boiling points of solvents, hence accelerating their evaporation and enabling quick drying of metal parts within a shorter cycle time.

Download free guidance paper: 10 questions key to selecting the right cleaning agent

The questions listed above are by no means exhaustive and there are many more factors to consider. More than just a necessity though, parts cleaning – when done properly – can deliver much more value than the mere technical function it fulfills, in terms of driving operational efficiency, savings and sustainability.

For a complete overview and in-depth explanations on the 10 key questions you should consider when selecting the right cleaning agent, download our free guidance paper.


Richard Starkey
Mobile: +44 (0) 7976 531695


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