Some cleanroom industries rely on a subjective, aesthetic evaluation of the cleanroom garment or number of launder cycles for replacement. Most cleanroom garment laundries have validated their processes for at least 100 launder cycles for the cleanroom garments they supply to the cleanroom industry. However, I recommend an objective testing of the cleanroom garment and fabric as well as establishing the efficacy of particle entrapment, the lack of particle shedding, and ESD efficacy as the criteria for replacement.

Since 2003, the IEST-recommended practice IEST-RP0CC003.3 has recommended specifications for clean-room fabrics, garment design, garment laundering, and testing of the cleanroom garments over time. The integrity and durability of cleanroom fabrics and design of clean-room garments have significantly improved in the last ten years. The laundering and testing of the cleanroom garments has been standardized.

The Helmke Tumble test evaluates the entire garment for shedding of particles from 0.3 µm to 10 µm. The specifications for Category I cleanliness is less than 1,200 particles at 0.5 µm and greater, cumulative, per feet per minute. The ASTM F 51 Alternate Method, Standard Test Method for Sizing and Counting Particulate Contaminant In and On Cleanroom Garments, evaluates one square foot of fabric for particle shedding of particles at 5 µm and greater and fibers. The particles on the filter can be identified as soluble, insoluble, or ionic by SEM/EDX or SEM/EDS. The specifications for Class A garments are less than 1,000 particles at 5 microns and greater and less than 10 fibers per square foot of fabric. The “body box” or particle containment test evaluates the entire cleanroom garment system in a simulated cleanroom environment. The EOS/ESD STD 2.1., ESD Association Standard Test Method for the Protection of Electrostatic Discharge Susceptible Items – Garments, or ASTM D-257, Standard Test Methods for D-C Resistance or Conductance of Insulating Materials, evaluates the surface resistivity and surface resistance of the fabric in the cleanroom garment. The static dissipative range for cleanroom garments is 105–11 ohms per square. The microbial penetration test evaluates the ability to entrain microbial particles. Additionally, there are other sophisticated supportive tests that can be performed to determine the identification of the particles generated from these tests such as SEM/EDX or SEM/EDS.

The same tests used to evaluate the cleanroom fabric can also be used to determine if and when the cleanroom garment should be replaced.

Some of the most common tests and the standards applicable to those tests are:

A percentage of change from the original test data can be an objective criterion to determine the replacement of the cleanroom garment.