Over the last few weeks we have looked at the function of different cleaners and detergents.
We’ve explained the ingredients used to make them and the equipment used to apply them. But the type of soiling and the type of surface are also areas that require expert understanding, particularly because their combinations are always different.
Like always, we work on a case by case basis, assessing the job before making decisions on what cleaning chemicals and equipment we should use. We need to be careful to understand the classification of the soil and the substrate we are trying to clean.
The first step in selecting the cleaner is classifying the soil deposits
We classify soils based on what liquid they become soluble. Whether it’s acid, water, alkali or a mix of the three, we will identify the soil before making the decision on what cleaning base to use.
All soils can be classified as one of the following:
- Soluble in water – includes sugars, most salts and some types of starches
- Soluble in acid – includes limestone and most mineral deposits
- Soluble in alkali – includes fats and proteins
- Soluble in a mix of the above three
When it comes to food soils, we often encounter mixtures of the above soil types. This complicates things further when selecting the correct cleaners. Food soils are tricky to work with but after years in the industry, we have the chemicals, equipment and expertise to tackle even the toughest jobs.
Soil types can complicate cleaner selection
The following soils are typical finds in food safety cleaning, even if they are not necessarily food deposits. Let’s take a closer look at each:
- Fats, oils and grease – these can be either waxy and solid or liquid, and both kinds are insoluble in water. When exposed to air they can become even more firmly adhered to the substrate.
- Proteins – also insoluble in water, proteins are complex materials. When exposed to hot water they can change shape, making them even more difficult to remove.
- Starches and carbohydrates – these are normally derived from plants and can vary from soft powders to hard deposits. We find they are usually soluble in water but if exposed to heat they can ‘caramelise’ which makes them more difficult to remove.
- Lime scale – these are typically from water drips and leaks.
- Corrosion deposits – areas of deterioration on metals such as steel and aluminium.
- Algae – found in moist areas with high levels of condensation. Requires particular chemicals to kill presence of harmful pathogens.
- Fungi – found in moist areas, particular near cold stores, freezers and silicone sealants. Also requires careful chemical treatment.
- Rubber marks – these are typically caused by fork lifts and trolley tyres in factory environments.
- Biofilms – these microorganisms can form invisible films if given the right conditions. These films often contain different types of organisms and usually require the use of extremely strong cleaners with an oxidising effect.
A cleaner varies between contaminated substrates
The substrate which is contaminated, is another major factor in choosing the right cleaner. In an ideal scenario, the surface is smooth, non-porous, abrasion resistant and chemically inert.
But this is not always what we are faced with, which is why we have plenty of options for those more stubborn surfaces.
The following substrates require different cleaning methods. Let’s take a look:
- Stainless steel – the higher the grade, the better. Value-engineered products have a tendency to corrode when chlorine-based cleaners are used.
- Zinc and aluminium – these metals are used as coatings on steel and are easily attacked by strong acid and alkali. If exposed to acid and alkali, zinc and aluminium can corrode and become brittle resulting in a substrate that is very difficult to clean.
- Concrete – this can become a very porous surface. Concrete is easily attacked by acid cleaners so alternative methods are carefully selected.
- Painted surfaces, plastics and rubber – these three vary in their resistance to chemicals and pressure washing. Each are susceptible to contamination by mould and fungi, and if they become flaky, their risk of contamination increases.
We often focus on the different types of chemicals and equipment used in our cleaning jobs, but the type of soil and substrate are just as much of a consideration.
Specialty knowledge is vital in understanding how best to clean the many possible combinations of soils and substrates.
To ensure you get the best possible result on your cleaning job, call us today!