ASTM D3273 Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber

Get Certified ASTM D3273 Testing for Reliable Mold Resistance Assessment

Interior coatings exposed to mold can discolor, bubble, peel, and develop a musty smell. ASTM D3273 testing guarantees paints and coatings are durable in moist environments. Qualified laboratory testing gives precise and repeatable data on quality control, product development, and comparative assessment. This testing assists manufacturers in creating coatings that are mould-resistant and promotes consumer confidence in products for use in bathrooms, kitchens, and basements. 

The scope of ASTM D3273 includes: 

• Material type: ASTM D3273 tests relative resistance to surface mold and mildew growth of interior coatings. 
• Purpose: ASTM D3273 evaluates the relative resistance of interior coatings to surface mold and mildew growth.
• Property measured: The selected test is a measure of the percentage of fungal growth coverage of the surface of the coated panel. 
• Method: The environmental chamber in ASTM D3273 is set to a temperature of 32.5 ± 1 °C with a relative humidity above 93 % to encourage the growth of moulds. 
• Result: The testing laboratory receives comparative performance ratings of the coating formulations it tests. 
• Test Limitations: The standard does not set acceptance criteria or specific service life for every system, as data is provided for comparison. 
• Environmental conditions: Fungal growth conditions are incorporated into the test program, with controlled temperature and humidity. 
• Applications: Engineers use ASTM D3273 to evaluate interior coatings for use in moisture-prone environments such as bathrooms, kitchens, and basements. 

What are the Uses of ASTM D3273 Testing?

ASTM D3273 testing assists laboratories in providing accurate data for coating quality evaluation. The results are utilized by manufacturers and engineers in product development, quality control, and selection of materials. This standard-

• Assessing mould resistance of interior paints and coatings
• Evaluation of antifungal additives and total levels for use
• Examine different coating products for moist/humid conditions
• Assisting with bathroom, kitchen and basement product development
• Data to control quality and ensure manufacturing consistency
• For coatings intended for use in an interior environment where mold is a potential problem, the estimation of performance needs to take into consideration the conditions that favor mold growth. 

Which materials can be tested under ASTM D3273?

ASTM D3273 deals with interior coatings such as sealants, varnishes and paints. The test method is suitable for evaluating coating systems on various substrates such as gypsum board, wood panels, and other interior building materials. The standard is designed for use to test interior coating systems and is not yet validated for exterior coatings. 

Why is ASTM D3273 Important?

ASTM D3273 is an accelerated test to evaluate the resistance of the interior coating to mold growth. Painted surfaces may develop mold that will affect the integrity of the paint, resulting in discoloration, bubbling, peeling of painted surfaces, and musty odors. This standard provides a means for manufacturers to create mold-resistant coatings, and for consumers to choose products for use in moist environments. The outcome helps engineers select coatings and to decide if a coating will achieve acceptable performance in interior conditions conducive to mold growth. For every rating, a better-performing coating will generally perform better in actual use, but the performance for any rating does not necessarily mean any specific period of time for a fungus-free coating. 

ASTM D3273 Testing Process and Data Collection

The testing process starts with preparing the soil and water content in the environmental chamber. The chamber temperature is set to 32.5 ± 1 °C and maintained for 24 hours. The suspensions have three fungal cultures and are spread evenly over the soil surface. The chamber is incubated for about 14 days to let the fungi grow and establish. Test panels are coated with coating material, then randomly hung vertically in the sporulating chamber. The exposure is continued for 4 weeks in controlled conditions. The panels are examined weekly, and the percentage of the surface covered with fungal growth is recorded following the ASTM D3273 grading system.

Common Challenges and Troubleshooting in ASTM D3273

Precise control of environmental conditions is essential to achieve accurate ASTM D3273 results. Reproducible results require tight control of temperature and humidity within the specified range. Mold growth on a film depends on the moisture level of the film and substrate. Issues that are common are humidity oscillations, temperature changes, contamination, and spore suspension concentration. High-quality results are obtained in the laboratory as a result of careful calibration of chambers, verification of sterility, application of even coating, and trained technicians who perform the tests according to standard procedures.

• The laboratory reports the fungal-growth rating on a scale from 0 to 10, with higher ratings indicating a greater percentage of surface remaining clear of fungal growth.
• Analysts assign a rating of 10 when the panel shows no fungal growth and 0 when fungal growth covers the entire evaluated surface.
• Technicians evaluate the panels at the specified weekly intervals and records the percentage of surface affected by fungal growth.
• Engineers interpret intermediate ratings based on the percentage of surface that remains clear, with each rating corresponding to a 10% increment in clear surface.
• Analysts compare fungal-growth ratings among coating specimens to evaluate differences in resistance to fungal growth under the specified test conditions.

Link to ASTM D3273