ASTM E2149 vs AATCC 100: Choosing the Right Antibacterial Textile Test

Quick insights

• ASTM E2149 and AATCC 100 are internationally recognized standards that evaluate antibacterial performance of textiles.
• The key difference in ASTM E2149 vs AATCC 100 is the testing mechanism: ASTM E2149 uses a dynamic shake-flask method, while AATCC 100 uses a static contact method to evaluate performance.
• ASTM E2149 is commonly suitable for hydrophobic and non-absorbent textiles, while AATCC 100 is suitable for absorbent and hydrophilic fabrics.
• Both tests generate provide quantitative bacterial growth reduction results, though the interaction between bacteria and test sample differs significantly.
• Selecting the right test matters as wrong selection leads to incorrect efficacy claims, inconsistent data and rejection of regulatory submissions.

Summary 

ASTM E2149 and AATCC 100 are both antimicrobial textile testing standards that are widely used, but they determine antibacterial performance of textile in different ways. ASTM E2149 is a dynamic flask shake method, specifically useful for non-leaching and hydrophobic antibacterial fabrics. In contrast, AATCC 100 is a static quantitative test which is more suitable to hydrophilic and absorbent fabrics. 

Why is it important to choose the right standard

Antibacterial textiles are applied in industries right from sportswear to medical textiles and bedding products. However, antibacterial efficacy results for these textiles vary significantly depending on the test method. The comparison of ASTM E2149 vs AATCC 100 helps choose the right standard.

Selecting the wrong standard may lead to:

• Inaccurate antibacterial performance claims
• Understated or overstated efficacy
• Lack of consistent and reproducible results
• Difficulties in meeting regulatory or buyer acceptance criteria
• Unreliable comparison between competing products or formulations

What is ASTM E2149?

ASTM E2149, developed by ASTM international, is used to evaluate the antibacterial activity of antimicrobial agents on treated textiles under dynamic contact conditions. The method is widely used for non-leaching antimicrobial technologies and hydrophobic textiles. The standard is specially useful when the textile material does not uniformly absorb bacterial inoculum .

What does the test measure?

• Percentage reduction of viable bacteria after exposure to treated textile.
• Quantitative assessment of antimicrobial performance

ASTM E2149 Test procedure: 

• Treated and untreated samples are placed in different flasks and inoculated with bacterial suspension
• The flasks are shaken to ensure good contact between bacteria and fabric samples. 
• After specified contact time, remaining microorganisms from each flask are enumerated and reduction in microbial count is compared with control test.  

Common applications – 

ASTM E2149 can be applied to the following products:

• Hydrophobic fabrics
• Paper
• Powder
• Granular materials
• Other solids

What is AATCC 100?

AATCC 100 is used to quantitatively evaluate the efficacy of antibacterial finishes applied to the  textiles materials. This test method is widely accepted in North America and internationally for assessing antimicrobial textile performance.

What the test measures 

• Reduction of bacterial population after contact with textile
• Quantitative assessment of antibacterial performance

Test procedure:

• Treated and untreated textile samples are inoculated with bacterial suspension
• Inoculated samples are incubated for a specific time period.
• Post incubations, a neutralizing solution is added to e samples. After incubation, neutralized samples are shaken, serially diluted and plated to quantify viable bacteria.
• Antibacterial activity is assessed by comparing bacterial reduction between treated and untreated samples.

Common applications – 

AATCC 100 is used for textile or porous material, such as 

• Woven, knitted, non-woven fabrics
• Wound dressings and medical gauze
• Healthcare textiles and bandages
• Bedding and home textiles
• Performance apparel

Also read 

•  ISO 20743 vs AATCC 100: How antibacterial activity in textiles is tested
• ISO 20743 vs JIS L 1902: Antibacterial Testing Standards for Textiles

ASTM E2149 vs AATCC 100 : Core difference 

Hydrophobic vs hydrophilic fabrics in antibacterial testing 

Hydrophobic and hydrophilic textiles behave differently during tests. This directly influences which standard should be selected.

What are hydrophobic fabrics?

Hydrophobic fabrics are water-repelling fabrics that inhibit moisture penetration, causing water to form a bead and roll off of the surface.

Examples include – Polyester, polypropylene, PU-coated textiles, synthetic performance fabrics.

Why is testing challenging for hydrophobic fabrics:

Hydrophobic textiles are difficult to test because –

• They repel aqueous/water-based inoculum
• Their microbial absorption is poor
• They have uneven contact with bacteria
• They have reduced wetting efficacy

Recommended test

In most scenarios,  ASTM E2149 is the suitable test as it uses a continuous shaking method that improves bacterial interaction with water-repelleing textile surfaces.

What are hydrophilic fabrics?

Hydrophilic textiles are water-liking materials. They can easily absorb water-based bacterial suspensions, allowing uniform microbial contact throughout.

Examples include:  cotton, wool, linen, and rayon 

Why do they perform well in static conditions:

Hydrophilic textiles have shown better consistency in static antibacterial evaluation as they:

• Can easily absorb bacterial inoculum
• Have better surface wetting properties
• Can maintain uniform microbial exposure throughout.

Recommended test 

In most cases, AATCC 100 test is suitable for absorbent and hydrophilic fabrics as it relies on direct bacterial contact under static conditions.

Why do results differ between methods?

Test results from ASTM E2149 vs AATCC 100 can be different even for the same sample as they use different testing setup and exposure conditions. 

Potential reasons:

• Dynamic shaking in ASTM E2149 vs Static contact in AATCC 100
• Level of bacterial contact with the textile surface differs
• Absorbency and moisture retention characteristics of fabric
• Variations in antimicrobial agents release mechanisms
• Changes in surface area interaction
• Improved microorganism to surface interaction for hydrophobic textiles under dynamic shaking conditions in ASTM E2149 

How to choose the right method 

Selecting between ASTM E2149 vs AATCC 100 depends on several technical factors:

• Choose ASTM E2149 for hydrophobic or water-repellent textiles where bacterial inoculum does not spread evenly across the surface. The dynamic shaking method improves microorganism contact.
• Choose AATCC 100 for hydrophilic and absorbent textiles like cotton, medical fabrics, and apparel, where direct bacterial inoculation better represents real-world usage conditions.
• Consider the antimicrobial technology type. Surface-bound or non-leaching antimicrobials are commonly evaluated using ASTM E2149, while textile antibacterial claims often rely on AATCC 100.
• Understand customer or regulatory requirements – Certain industries and buyers explicitly specify preferred antimicrobial testing standards.

Common mistakes while selecting the test standard

• Ignoring fabric absorption properties – Hydrophobic fabrics can produce inconsistent results in static tests like AATCC 100 because bacterial inoculum does not spread uniformly
• Choosing test based only on marketing claims – The test method align with the actual fabric structure and antimicrobial mechanism rather than just marketing claims
• Not understanding Leaching vs Non-leaching technologies – Non-leaching antimicrobial technologies may behave differently than leaching technologies in ASTM E2149 vs AATCC 10 testing environments

Conclusion

Understanding the differences between ASTM E2149 vs AATCC 100 is essential for selecting the appropriate antibacterial textile testing method.  s. While both standards provide quantitative antibacterial evaluation, they differ significantly in bacterial exposure conditions, textile compatibility and antimicrobial interaction mechanisms. As antibacterial textile technologies continue to advance, choosing the correct test method remains important for generating scientifically correct, reproducible and application relevant performance data.

Need help with choosing the right standard

Selecting the right  textile antibacterial testing standard plays an important role in product validation, durability assessment, and market credibility. 

At MIS,  we offer testing services for both hydrophobic and hydrophilic textiles using ASTM E2149 and AATCC 100 test standards. We generate accurate, reliable, and reproducible  test result data, our customers can rely on. Need assistance identifying the most suitable test standard for your application? 

Connect with our experts today. 

FAQs

1. What is the main difference between ASTM E2149 and AATCC 100?

ASTM E2149 uses dynamic shaking conditions to enhance bacterial contact with the textile surface, while AATCC 100 uses static direct inoculation without agitation

2. Which test is better for hydrophobic textiles?

ASTM E2149 is generally the preferred method for hydrophobic textiles

3. Which test is suitable for cotton fabrics?

AATCC 100 is suitable method for cotton fabric as it is a hydrophilic textile.

4. Why do hydrophobic fabrics behave differently during antibacterial testing?

Hydrophobic textiles repel aqueous bacterial suspensions, which can reduce direct microbial interaction and lead to inconsistent results in static tests.

5. Is ASTM E2149 qualitative or quantitative?

ASTM E2149 is a quantitative antibacterial test method that measures percentage reduction of bacterial growth post incubation

6. Can ASTM E2149 and AATCC 100 results be directly compared?

Not always, because both methods use different bacterial exposure conditions and interaction mechanisms which can influence antibacterial reduction values.

7. Which method is more stringent: ASTM E2149 vs AATCC 100?

Neither method is universally more stringent, the suitability depends on fabric absorbency, antimicrobial technologies used,  and intended product application.

8. Do retailers or buyers prefer one standard?

Some retailers, brands or regulators specify either ASTM E2149 or AATCC 100 depending on product category, market region and performance expectations.

9. Why do some textiles pass ASTM E2149 but fail AATCC 100?

Certain textiles such as hydrophobic or non-leaching materials, require dynamic shaking conditions where bacterial contact needs to be artificially enhanced and hence may fail AATCC 100 as it is a static test method.