Desiccants are hygroscopic substances that induce a state of dryness or desiccation in their vicinity. Desiccants have porous surfaces that help absorb water vapours from the air and moist materials; there are physical and chemical desiccants. Food products are frequently exposed to moulds and bacteria in a high-humidity atmosphere, resulting in food spoilage and discolouration. Excessive humidity will often lead to metal oxidation in electronic products, leading to damage. The presence of moisture in medication packaging can harm the effectiveness of medicines. Use Desiccants inside the product packaging to prevent defects in electronics, spoilage of food products, and medicines wastage due to excessive humidity or moisture. Desiccants are in packets in sheets, moulded polymers, sachets, and others.
Types of Desiccants
Below are five common types of desiccants.
Silica Gel is a harmless traditional desiccant frequently used in the healthcare and electronics industries. Silica Gel is an excellent drying agent to absorb moisture and protects against contamination, spoilage, and mould growth. There are three distinct degrees of humidity detection and control: white, blue, and orange colours. It is an amorphous silicon dioxide with an uneven atom structure.
Activated Alumina is often used in heavy industrial applications for various purposes, including adsorbing catalysts and eliminating fluoride and pollutants. Activated Alumina can adsorb substances such as gases and liquids. The desiccant is often to used to filter fluoride, arsenic, and selenium from drinking water.
Activated Clay is a naturally porous mineral dried to produce an adsorbent material. It primarily protects products in industrial packaging and comes in slightly coarser granules than Silica Gel. The desiccant is an excellent alternative to Silica Gel due to its high efficiency and lower cost.
Molecular Sieves are synthetic zeolite materials engineered with pores of precise and uniform structure and size, allowing the desiccant to adsorb gases and liquids based on molecular size and polarity. The four main types of Molecular Sieves are 3A, 4A, 5A, and 13X. The type depends on the molecule’s chemical formula, which determines the Molecular Sieve’s pore size. A Molecular Sieve works by adsorbing gas or liquid molecules smaller than its pores’ effective diameter while excluding those larger than the openings.
Activated Carbon is processed to have tiny pores that increase the surface area for adsorption or chemical reactions. Activated carbon is a cost-effective approach to treating large volumes of gas or water containing low levels of pollutants. Water, air, gas treatment and odour control are all typical uses for Activated Carbon.
Usage of Desiccants
Silica Gel & Activated Clay
- Sachet Form – can be directly used by hand to put into product packaging
- Roll Form – can be put into packaging by machine in which the device will detect an eye mark on the sachet packing and cut it
- Loose Form (Silica Gel) – can be directly poured into the place you want to put Silica Gel in, such as transformer breathers
During the process, Activated Alumina can be put into a water filter to remove any fluoride present in the water.
Loose forms of Molecular Sieve can be directly put into absorption vessels to help dry liquefied petroleum gas.
Activated Carbon can be directly put into a water filter for the drinking water filtration process, which helps reduce pollutants in water.
Benefits of Desiccants
Prevent Product Damage from Moisture
- Keeps food crispy and avoids deterioration of food products
- Absorbs moisture in electronics products, protecting circuit boards against moisture damage
Cost-Effective and Prevent Wastage
- As long as moisture damage is avoided, there will be a decrease in wastage and product damage.
- Placing desiccants in packaging can be done quickly. Also, roll-form desiccants utilise machines in the packing process.
Desiccant Present Virtually No Health Concerns
Desiccants are non-toxic and harmless and can be found packaged alongside food items. However, consuming them might cause unpleasant health concerns, including nausea, vomiting, and headaches.
Applications of Desiccants
- Desiccants help the oil and gas industry and the electric power transmission process.
- Silica Gel is commonly used with food, medicine, and supplement products to prevent moisture, which reduces the product’s shelf life.
- White Silica Gel is deemed “Generally Recognised as Safe,” suggesting that it can be added to food products.
- Molecular Sieves help dry liquefied petroleum gas, while Silica Gel helps to ensure that the air is always dry and moisture-free during the electric transformation process.
- Airline companies often use desiccants – When an aircraft engine has to be repaired or be under maintenance work, technicians will place desiccants at specific parts of the machine to ensure that the components or functions of the engine will not be affected by moisture and be corrosion-free
VCI (Volatile Corrosion Inhibitor)
VCI stands for Volatile Corrosion Inhibitors. The VCI chemical compounds will release vapours into an enclosed space to prevent corrosion on a metal surface, and it is ideal for keeping enclosed void spaces rust-free. They protect metal parts from rusting while in use, storage, or in transit. They have sufficient vapour pressure to release molecules from the compound into the air. VCIs come in various formulations, such as films, oils, coatings, cleaners, etc. They’re also a variety of formulations that protect ferrous, nonferrous, or multi-metal applications. Corrosion happens when an electrolyte is present on the surface of a metal. The electrons then flow from high-energy areas of the metal to low-energy areas in a loop through the electrolyte. The corrosion effect will result in the formation of oxidation on metal surfaces. With the presence of VCI, electrical current cannot flow from the anode through the electrolyte into the cathode. The VCI molecules are attached to a metal surface to form an invisible, thin layer to prevent rust.
Types of VCI (Volatile Corrosion Inhibitor) Products
All VCI products come with different specs/types for ferrous, nonferrous, and multi-metal.
The VCI Paper is a kraft packaging paper manufactured with added VCI chemistry. VCI molecules protect metals from corrosion by forming a thin, invisible layer on the surface that inhibits the corrosion caused by oxygen, water, and contaminants. VCI Paper can be made in different sizes, weights, and inhibitor types and can be ordered in rolls, pre-cut, and with custom printing. VCI Paper is typically a kraft material but can be reinforced with a poly layer or scrim-like threads for additional protective properties. It is also sometimes referred to as “rust inhibitor paper”.
The VCI Film is in direct contact with the metal. VCI molecules adsorb on the metal surfaces, creating an invisible molecular barrier against corrosive elements such as oxygen, moisture, and chlorides. As the VCI molecules vaporise out of the film and diffuse throughout the package, they form a protective molecular layer on metal surfaces. The molecular layer is not in direct contact with the film. When the packaging is removed, the VCI molecules vaporise and float away.
VCI Emitters, also known as VCI diffusers, provide targeted corrosion protection in hard-to-reach enclosed spaces. VCI Emitters emit powerful corrosion-inhibiting molecules into an enclosure that settles on metal surfaces and protects them from corrosion. They are safe for electronic products. The chemicals are odourless, non-toxic, residue-free, and designed to work in restricted spaces.
Once the VCI Liquids have been adsorbed on the surface of the metal, it provides an effective hydrophobic barrier that prevents moisture from getting through to the metal surface. Consequently, this prevents the formation of corrosion. There is a wide range of rust inhibitor coatings ranging from oil-based, solvent-based, water-based, and grease-based to oil additives to protect parts in-between production processes and storage.
The VCI Bag is a poly packaging film converted to a bag manufactured with added VCI chemistry. VCI molecules protect metals from corrosion by forming a thin, invisible layer on the surface that inhibits the corrosion caused by oxygen, water, and contaminants. The VCI Bag can be made in different sizes, weights, seals, and inhibitor types.
The VCI Powder is designed to protect metal surfaces in large voids from corrosion. It offers VCI protection combined with a new self-fogging Flash Corrosion Inhibitor (FCI™) technology specialised to protect metals in enclosed spaces. This combination diffuses rapidly to protect against flash rust and provides long-term corrosion protection with its progressive vapour-transported corrosion inhibitor action. The powder is fully water-soluble and is effective in wet lay-up applications.
Usage of VCI (Volatile Corrosion Inhibitor)
VCI Paper & Film
- Can directly wrap products and ensure that they are all in clean and dry conditions, at room temperature, and wrapped securely
- Avoid direct contact with metal with wood, paper, or cardboard to prevent the appearance of moisture and acid.
- Remove the product from the packaging
- Minimum of 1 to 2 years shelf life
- Place the diffuser in an ideal location
- Ensure that the airflow is restricted in the enclosure
VCI Liquid & Powder
- Mix with water before applying to a metal surface
- The mixture formula or ratio should be based on the user’s requirement depending on medium-term wet lay-up (4-6 months) or long-term wet lay-up (6-12 months)
- Must dilute with DI water or RO water as pipe water contains chloride, which may affect the effectiveness of the VCI molecules
- After the mixture is done, apply the liquid to the product by dipping, spraying, or brushing it onto the metal surface.
- Make sure metal parts are in a dry and clean condition
- Wear gloves when placing the metal parts into the VCI Bag
- The temperature of the metal parts must be at room temperature, and ensure that packages are tightly sealed with tape or heat seal
- For tight or layered packages, use an interleave for added protection
- Avoid direct contact with metal with wood, paper, and cardboard to prevent the appearance of moisture and acid
Benefits of Using VCI (Volatile Corrosion Inhibitor)
Provide Robust Corrosion Protection
VCI products prevent metal products from corrosion on surfaces and in limited spaces.
Easy and Safer to Use
- VCI products are clean and dry and are ready to use right out of their packaging
- No personal protection is needed during the packing or coating process
- Use clean gloves without lint or talc to keep metals free of corrosion and contaminants
- Compared to other engineering oil lubricants, VCI products are much safer
- VCI products are easy to handle during the packing or coating process
- VCI products provide protection that lasts long for 1 to 2 years. Users do not need to keep replacing their VCI products
- Less costly compared to other corrosion-preventing products
Applications of VCI (Volatile Corrosion Inhibitor)
VCI products can be used widely in many industries, such as electronics, engineering, shipping, automotive, etc.
- Zerust® ActivPowder™-10F replaces thick tar-like greases and oil-based coatings in sealed voids, such as ship hulls and pipelines. The VCI Powder diffuses to reach and protect internal structures where sweating and condensation of trapped humidity typically cause corrosion issues.
- Vapour emitters protect electronic enclosures from corrosion during operations and are marked with the installation date for the replacement