Sorbency: Meaning and relevance to wipes
11 Nov 2015
Posted by John Corley
Cleanrooms and other controlled environments require stringent contamination control. This is often achieved through the use of clean wipes or wipers. Advances in technology have led to the creation of a range of wipers designed to suit different cleanroom applications, and with so many specific types, choosing the correct wiper requires consideration of more than just cost and cleanliness. It requires an understanding of sorbency, the ability of a wiper to absorb and retain liquids, relative to your cleanroom needs.
Sorbency Rate vs. Capacity
Sorbency rate and capacity are the two most important parameters to consider when choosing a wiper. The Institute of Environmental Sciences and Technology (IEST) standard* describes the methods for measuring both. Sorbency rate is a measure of the speed at which a wiper can absorb a liquid. Sorbency capacity is a measure of the amount of liquid a wiper can hold. Sorbency rate is critical when clean-up speed is paramount. A high rate can absorb liquids faster, saving your employees time, or removing a potential safety hazard as quickly as possible. Capacity is critical when handling large amounts of liquid. A higher capacity could mean less Wipes are needed, saving you time and money.
Hydrophobic vs. Hydrophilic Materials
Wiper sorbency is greatly influenced by the type of material used and the surface treatments applied during manufacturing. Wipers can be made to be hydrophilic, meaning that they attract water, or hydrophobic, meaning that they repel water. To help you remember which is which, try this mental trick: Phobic is derived from the Greek word Phobia meaning “Fear”. If the liquid is afraid of the Wipe, it won’t absorb. Philic is derived from the Greek word Philia meaning “Love”, or in this case the liquid is happy to absorb into and join with the Wipe.
Hydrophilic wipers absorb water-based liquid spills more thoroughly and rapidly than hydrophobic wipers, potentially reducing the risk of residual surface contamination. However, they tend to be less clean and can themselves serve as sources of contamination. Hydrophobic wipers absorb hydrocarbon-based liquids, such as oil and petroleum, while repelling water, and thus protect critical or sensitive surfaces where water is present.