What Fabric for Cleanroom Wipes?

Overview of Cleanroom Wipes

A cleanroom wipe, also known as a lint-free cleanroom wipe, is a specialized tool designed to eradicate contaminants, particulates, and residual materials in critical manufacturing, pharmaceutical compounding, and other environments where cleanliness is paramount.

Cleanroom wipes are generally low-lint or lint-free. But their performance varies based on their application, material composition, and ISO classes. Some wipes may have additional features such as solvent compatibility or ESD-safe properties.

A cleanroom wipe’s absorbent, low-lint materials enable tight control of moisture, solvents, and spills. This makes them ideal for cleaning a cleanroom’s surfaces, walls, machinery, tools, and other production materials.

Historically, the cleanroom wipe is the most effective and commonly used tool for removing contaminants and particulate material in critical environments.

Understanding Woven and Nonwoven Fabric for Cleanroom Wipes

Cleanroom wipes can be broadly categorized into woven and nonwoven types, each with benefits and drawbacks.

Nonwoven Wipes

Nonwoven fabrics, as the name suggests, are not woven or knitted. Instead, they are bonded by entangling fibers or filaments. The manufacturing process may involve heat, special chemicals, or machinery to produce the nonwoven material. The result is an economical sheet or web-like structure that doesn’t require any laundering process.

Some nonwoven wipes are compatible with gas sterilization. However, it may be easier to pre-purchase sterilized wipes.

Woven (Knit) Wipes

Woven wipes are formed by winding monofilament or other materials, resulting in a low-lint or lint-free cleanroom wiper with excellent tensile strength.

Woven fabrics offer low levels of non-volatile residues (NVRs), making them ideal for critical class environments.

Material Analysis of Cleanroom Wipes

Let’s delve into the different materials used in manufacturing cleanroom wipes, their properties, and their ideal use cases.

Polyester Wipes

Polyester cleanroom wipes are known for their durability and exceptional cleanliness. They are strong, non-shedding, and soft. The edges of these wipes can be melted to prevent loose ends and linting. They are commonly used in ISO 3-4+ (Class 1-10) Cleanrooms.

Polyester/Cellulose Wipes

Polyester/Cellulose or Polycellulose cleanroom wipes typically feature a 55/45 mix of cellulose and polyester hydroentangled for a chemically pure wipe down. They are clean, absorbent, and economical for ISO Class 6 and above cleanrooms.

Polypropylene Wipes

Polypropylene wipes are soft, non-abrasive, and resistant to solvents. They are suitable for wiping sensitive surfaces and components and are commonly used in ISO 6 (Class 1000) cleanrooms.

Cotton Wipes

Cotton wipes are economical, durable, and environmentally friendly. They are highly absorbent and work well with IPA (Isopropyl Alcohol) and other solvents. Most cotton wipes are not rated for cleanrooms.

Foam Wipes

Foam wipes are non-abrasive and solvent-resistant, making them suitable for wiping sensitive surfaces and components such as optics and printheads. However, foam swabs are more common because of their precision cleaning features.

Microfiber (Nylon) Wipes

Microfiber cleanroom wipes, made from nylon, have a soft, ultra-fine surface, are abrasion-resistant, and are durable for wiping various surfaces.

Selection Process of Cleanroom Wipes

Choosing the right cleanroom wipe comes down to understanding the specific requirements of your cleanroom environment. You must consider several factors, such as the level of cleanliness required, the type of contaminants present, and the surfaces to be cleaned.

Here are a few steps to help you choose the right cleanroom wipe:

1. Identify the Required Cleanliness Level: The first step is to identify the cleanliness level required by your cleanroom. This can be determined by the ISO Class of your cleanroom.

2. Understand the Contaminants: Different cleanroom environments will have different types of contaminants. Understanding the type of contaminants in your cleanroom will help you choose a wipe that can effectively remove these contaminants.

3. Determine the Wipe Material: You can determine the wipe’s most effective material based on the required cleanliness level and the type of contaminants. For instance, polyester wipes are suitable for ISO Class 3-4+ cleanrooms, while polypropylene wipes are suitable for ISO Class 6 cleanrooms.

4. Consider the Wipe Size and Packaging: The wipe size should be appropriate for cleaning the surface area. Also, consider the packaging of the wipes. For instance, pre-saturated wipes are usually packaged in resealable pouches for convenience and to maintain their saturation level.

5. Evaluate the Cost: Finally, consider the cost of the wipes. While some materials may be more expensive than others, they may offer better performance and may be more cost-effective in the long run.

Types of Cleanroom Wipe Edges

The edges of a cleanroom wipe can significantly impact its performance. There are mainly three types of cleanroom wipe edges:

1. Knife Cut Edges: This is the most economical option and is typically used for less critical cleanroom applications. However, these edges are prone to linting or particle shed.

2. Laser Sealed Edges: These edges are exact and cause minimal disruption to the surrounding material. They offer effective control of particulate with a non-abrasive edge.

3. Ultrasonically Sealed Edges: Ultrasonic heat cuts and seals the edges, resulting in a cleanroom wipe with lower carbon levels and a precisely formed, stable edge. These wipes offer the highest grade of particle retention and cleanliness.

Types of Nonwoven Cleanroom Wipes

Nonwoven cleanroom wipes come in various types, differentiated by their manufacturing processes. These include:

1. Meltblown: This process involves using heat to bond ultra-fine polypropylene fibers, resulting in a uniformly flat surface with excellent particle removal characteristics.

2. Hydroentangled: This process entangles and cleans the fibers without using binders or other potential contaminants.

3. Spunlaced: Applies low-impact water jet energy to a fabric web and vacuum dewatering, resulting in a wipe that is useful for wiping down various surfaces.

Low Lint Wipes

Low-lint wipes are made of all-purpose industrial nonwoven material, making them durable and low-linting for use outside the cleanroom or in a controlled environment. These wipes are perfect for applications requiring minimal linting or particle generation.

Sterile Wipes

Sterile cleanroom wipes have undergone gamma irradiation to eliminate all living organisms. These wipes are available in different styles, including gamma-irradiated, validated clean, and low pyrogen or endotoxin level wipes. Sterile wipes ensure cleanliness in critical drug compounding areas such as intravenous IV preparation or sterile packaging.

Presaturated Cleanroom Wipes

Presaturated cleanroom wipes are pre-wetted with a specific amount of solvent or cleaning solution, simplifying the wipe-down process and providing higher cleanroom safety. They are available in many materials, answers, and packaging styles.

Best Practices for Cleanroom Wiping

Here are a few best practices for cleanroom wiping:

1. Only use cleanroom-approved wipes.
2. Do not allow any tool to rest on the surface of a bench or table; instead, place it on a cleanroom wipe.
3. All non-packaged items entering a cleanroom should be wiped down with a suitable solution.
4. Regularly apply sterile IPA (Isopropyl Alcohol) to disinfect surfaces, compounding sites, and gloves.
5. Dispose of solvent-soaked wipes in the proper solvent cans.

Understanding cleanroom wipes’ types, materials, and uses is pivotal in maintaining cleanroom standards. It’s crucial to select the right cleanroom wipe that meets the specific needs of your cleanroom environment. Remember, a cleanroom can never be cleaner than the wipe used.