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ASTM D2574 Antimicrobial Paint Test (In-Can Preservative Efficacy)
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Summary
ASTM D2574 is performed to evaluate the resistance of emulsion paints to microbial attack in the container. ASTM E 2574 testing involves exposing paint samples to mixed bacterial and fungal cultures to check the resistance to microbial growth. This test is usually performed during formulation development and helps the manufacturers with preservative selection. It also supports quality control by ensuring paints remain stable and resistant to microbial deterioration.
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Quick understanding about test
ASTM D2574: 2016 - Standard Test Method for Resistance of Emulsion Paints in the Container to Attack by Microorganisms
ASTM D2574 is used to assess the resistance of emulsion paints against microbial attack in the container or tank.
Applicable to emulsion paints containing biocides, helping manufacturers optimize preservative selection.
- Pseudomonas aeruginosa (ATCC 10145)
- Klebsiella aerogenes (ATCC 13048)
- Bacillus subtilis (ATCC 27328)
- Test samples and control samples are prepared and inoculated with specific microbial strains. Inoculated samples are incubated for 7 days. After incubation, samples are monitored for microbial growth and changes in physical properties.
- Ensures microbial resistance and product quality.
- Prevents product recalls and damage from microbial contamination.
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What is ASTM D2574?
ASTM D2574 is a broadly accepted standard which provides the testing conditions, specifications, and method for evaluating emulsion paints’ resistance to microbial attack in containers. Under optimal conditions, microorganisms can thrive in emulsion paints and cause various types of deterioration, like loss of viscosity or foul odor. The test allows paint manufacturers to choose an appropriate biocide that can help retain the paint’s quality throughout its shelf life.
Scope of ASTM D3273 standard
ASTM D2574 test is widely used to evaluate the in-can preservative effectiveness of water-based products against microbial contamination.Scope of testing includes –
- Paints and coatings
- Architectural coatings
- Industrial coatings
- Adhesives and sealants
- Construction materials
ASTM D2574 test requirements
Test conditions – The test is to be conducted at a constant temperature of 30°C ± 2°C.
Sample preparation – Biocide-treated (Test sample) and untreated (control) samples are required for testing.
- Test organisms – Pseudomonas aeruginosa (ATCC 10145) and Enterobacter aerogenes (ATCC 13048) are used as standard test organisms. Additional strains, such as Bacillus subtilis (ATCC 27328), can be included upon client request
ASTM D2574 step-by-step test procedure
Samples are tested against the challenge organisms for 2 cycles
Cycle 1 – Initial microbial challenge
- Each test sample is inoculated with 0.1 mL of test organisms.
- The inoculated samples are incubated and bacterial recovery is assessed at Day 1, 2, 5 and 7 by streaking onto agar plates.
- The agar plates are then incubated for one week.
- After 7 days, plates are evaluated for bacterial recovery.
Cycle 2 – Re-inoculation On Day 7, the test samples are re-inoculated with 1.0 mL of each test organism.
- Incubation followed by bacterial recovery is repeated the same as for cycle 1.
ASTM D2574 results and rating interpretation
Efficacy rating scale
Rating | Description |
0 | No bacterial recovery. |
1 | Trace of contamination (1 to 9 colonies) |
2 | Light contamination (10 to 99 colonies). |
3 | Moderate contamination (>100 distinct colonies). |
4 | Heavy contamination (continuous and indistinguishable smears of colony growth) |
ASTM D2574 vs other tests
Parameter | ASTM D2574 | ASTM D4783 | ASTM D3273 |
Purpose | To evaluate the in-can effectiveness of preservatives in water-based paints and coatings | To evaluate resistance of liquid adhesive preservatives to microbial attack in their containers | To evaluate the resistance of interior coatings and paint films to fungal/mold growth under highly humid and warm conditions |
Mandatory test strains | Pseudomonas aeruginosa (ATCC 10145) and Enterobacter aerogenes (ATCC 13048) | Bacteria : Pseudomonas fluorescens, Pseudomonas aeruginosa, Bacillus subtilis, Proteus vulgaris Fungi & Yeast : Aspergillus niger, Aspergillus flavus, Penicillium pinophilum, Andida tropicalis, Candida pseudotropicalis, Kluyveromyces fragilis | Aureobasidium pullulans (ATCC 9348), Aspergillus niger (ATCC 6275), and Penicillium species |
Scope of products | Emulsion paints | Liquid adhesive preparations | Interior coatings, paint films and other treated surfaces. |
Results | Uses a visual rating scale from 0 to 4 | Uses a growth rate scale from absence of growth to heavy growth | Uses a visual rating scale from 0 to 10 |
Why do paints fail ASTM D2574 testing?
Paints can fail ASTM D2574 testing because of various reasons. Common causes may include:
- Insufficient concentration of preservative
- Poor biocide compatibility
- High Microbial load contamination
- Improper formulation stability – changes in pH, viscosity or ingredient interactions
- Selected biocide spectrum does not target relevant bacteria or fungi
Regulatory and product development relevance
ASTM D2574 is an important standard to validate quality assurance as well as achieve regulatory approval for emulsion paints.
Key advantages of ASTM E2574 are:
- This test method substantiates claims on product stability by demonstrating resistance to microbial spoilage.
- It prevents costly product recalls caused by odor formation or any contamination.
- It helps optimize formulation of the product, achieving effective preservative systems.
- It helps achieve compliance with global quality standards
When to choose ASTM D2574?
- If you product is emulsion paint/coating (water-based)
- During formulation development to select an effective preservative
- As a part of quality control to ensure product shelf and safety against microbial contamination
- Needs evidence of preservative efficacy before market launch
Importance of ASTM D2574 Antimicrobial Paints Test
Paints stored in containers are at constant risk of microbial spoilage. Contamination not only affects product performance but also leads to foul odors, reduced shelf life, and customer complaints.
ASTM D2574 plays a key role in ensuring the quality and stability of emulsion paints. This standard helps manufacturers confirm that their preservative systems are strong enough to protect the paint during storage and distribution. By verifying microbial resistance, ASTM D2574 not only safeguards product integrity but also reduces the risk of customer complaints, financial losses, and damage to brand reputation. Since it is an internationally recognized ASTM standard, it also provides credibility, supports regulatory compliance, and gives customers confidence in the durability and reliability of the paint.
Why choose MIS for ASTM D2574 testing
At Microbe Investigations Switzerland, we deliver precise ASTM D2574 testing to validate if your paints withstand microbial attack and maintain quality.
Besides ASTM D2574, we also provide ASTM D4783 testing to evaluate the resistance of adhesive preparations against bacteria, yeast, and fungi.
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Frequently Asked Questions
DR. Martinoz Scholtz
In-can preservative test evaluates if the preservatives in paints can resist microbial growth when stored inside the container.
Bacterial growth is observed often in water-based paints, leading to odor, spoilage and reduced shelf life. Hence, antimicrobial preservatives play an important role in resisting microbial growth in water-based paints.
The paint samples are inoculated with bacteria and incubated for a specified time. Post incubation, microbial survival is measured over time.
If a paint fails ASTM D2574 test, it indicates a weak preservative system, meaning the paint can be attacked by microorganisms during storage. In such situations, reformulation of the paint and retesting is performed.
No, ASTM D2574 is primarily designed for water-based emulsion paints. Other test methods can be used for solvent-based paints.
Common strains used in paint testing include Pseudomonas aeruginosa, Klebsiella aerogenes and Bacillus subtilis.
It typically requires 2-3 weeks.
The limitations include its scope of applicability as it applies only to emulsion paints.
In-can preservative test is used to evaluate the resistance of paint preservative system to microbial attack whereas dry film test is used to assess the surface resistance to microbial attack after application of paint.
In-can preservative test is used to evaluate the resistance of paint preservative system to microbial attack whereas dry film test is used to assess the surface resistance to microbial attack after application of paint.
Right biocide for paints can be selected based on factors such as microbial spectrum, compatibility with paint ingredients, solubility, durability in wet or dry conditions etc. This can be achieved through rigorous in accordance with standards such as ASTM E2574.
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