Mold growth test service

Mold Growth Test Service – Evaluating Fungal Resistance and Material Durability for Brazilian Climatic Conditions

As an ISO/IEC 17025 accredited independent testing laboratory, we provide comprehensive mold growth testing services to Brazilian manufacturers, importers, and quality assurance professionals across the construction, textile, automotive, electronics, packaging, and healthcare sectors. Brazil's tropical and subtropical climate – with high relative humidity and elevated temperatures – creates ideal conditions for fungal proliferation, which can degrade materials, compromise product performance, and pose health risks to end‑users. Our test protocols expose specimens to controlled fungal spore suspensions under defined temperature and humidity conditions to quantify resistance to mold colonization, evaluate visual deterioration, and assess changes in mechanical, electrical, or aesthetic properties. All methods are aligned with ABNT NBR standards, ASTM G21 (Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi), ISO 846 (Plastics – Evaluation of the action of microorganisms), IEC 60068‑2‑10 (Environmental testing – Test J and guidance: Mold growth), ASTM D3273 (Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber), and ASTM D6329 (Method for Developing a Standardized Fungal Inoculum). Our reports are recognised by INMETRO (product safety certification), ANVISA (healthcare and medical device approval), ABNT (technical compliance), and IBAMA (environmental assessments).

Materials and Products We Regularly Test for Mold Growth

Our mycology laboratory accommodates a diverse range of organic and synthetic materials that are susceptible to fungal attack. Typical test specimens include:

• Building and construction materials – gypsum boards, thermal insulation (foams, mineral wool), wood and wood composites, sealants, and coatings
• Textiles and fabrics – cotton, wool, synthetic fibres, upholstery, and non‑wovens for apparel, automotive, and technical applications
• Polymers, plastics and rubbers – PVC, polyethylene, polypropylene, polyurethane, silicone, and elastomeric seals
• Paints, varnishes and surface coatings – interior and exterior architectural coatings, industrial finishes, and anti‑graffiti layers
• Paper, cardboard and packaging materials – corrugated board, coated papers, labels, and adhesive‑backed films
• Electronic assemblies and components – printed circuit boards, conformal coatings, potting compounds, and cable insulation
• Medical devices and pharmaceutical packaging – polymer housings, tubing, syringe components, and blister foil
• Furniture and consumer goods – leather, synthetic leather, mattress materials, and child‑care products

Building and Construction Materials – Surface Mold Resistance in High‑Humidity Chambers

• Mold resistance test for interior coating surfaces (ASTM D3273 / ABNT NBR 15458) – We apply the coating material to standard substrate panels and place them in an environmental chamber maintained at 32 °C and 95‑100 % relative humidity. The specimens are inoculated with a mixed fungal spore suspension containing Aspergillus niger, Penicillium citrinum, Aureobasidium pullulans, and other common mold species. The chamber is operated for a minimum of 4 weeks, and we visually rate the extent of fungal growth on the coating surface every 7 days using a 0‑10 rating scale (0 = no growth, 10 = heavy growth covering > 90 %). A rating of 7 or better is considered acceptable for Brazilian interior finishes.
• Fungal resistance of thermal insulation foams (ASTM C1338 / ISO 846 adapted) – We test rigid and flexible foams (polyurethane, polystyrene, phenolic) by placing specimens (50×50×10 mm) in a sterile petri dish on a mineral salts agar medium. The mixed spore suspension is applied uniformly, and the plates are incubated at 28‑30 °C and 90‑95 % RH for 28 days. The extent of growth on the specimen surface is rated using a 0‑5 scale (0 = no visible growth, 5 = extensive growth and visible degradation). For Brazilian building projects, an acceptance rating of ≤ 2 is typically required to avoid insulation degradation.
• Wood rot and decay test (ASTM D2017 / EN 113 adapted) – For wood and wood‑based panels, we conduct a soil‑block test using basidiomycete fungi (e.g., Coniophora puteana, Gloeophyllum trabeum). The specimens are buried in a sterile soil substrate containing the fungal inoculum and incubated for 12 weeks. The loss in flexural strength or the weight loss percentage is reported; a weight loss exceeding 20 % is considered a failure for structural applications in Brazilian construction.
• Effect of cleaning and water immersion on mold resistance – For materials that may be cleaned frequently or exposed to water, we pre‑condition specimens by washing with a standard detergent and drying, or by immersing in water for 72 hours, before the mold test. The change in mold rating is reported as a durability index.

Textiles, Fabrics and Non‑Wovens – Fungal Staining, Odour and Strength Loss Assessment

• Mold resistance for textile materials (AATCC 30 / ISO 11721‑1 adapted) – We inoculate fabric specimens (10×10 cm) with a fungal spore suspension containing Aspergillus niger, Aspergillus flavus, and Chaetomium globosum. The specimens are then incubated on a nutrient‑free agar or under a controlled humidity chamber (95 % RH, 28 °C) for 28 days. We evaluate the degree of fungal growth on the surface (0‑5 rating), the presence of fungal staining (colour change measured by spectrophotometer), and the tensile strength retention. A loss of tensile strength > 30 % or a rating > 2 is considered unacceptable for Brazilian upholstery and clothing applications.
• Odour development test after fungal exposure – For materials used in automotive interiors and footwear, we conduct a sensory evaluation by a trained panel to detect any musty or earthy odours after the mold test. The intensity is rated on a 0‑5 scale, and the threshold for acceptance is typically ≤ 2.
• Resistance to fungal degradation of coated textiles – For PVC‑coated or polyurethane‑coated fabrics, the mold test is performed on the coated side and on the uncoated back. The adhesion of the coating to the substrate is measured before and after the test using a peel test (ASTM D413); a loss > 15 % indicates fungal attack at the interface.
• Effect of laundering and dry‑cleaning on antifungal protection – For textiles treated with antimicrobial or antifungal finishes, we conduct the mold test on the as‑received fabric and again after 10 laundering cycles (ISO 6330). The retention of mold resistance (e.g., from rating 1 to 3) is reported, ensuring that the treatment withstands routine care.

Polymers, Plastics and Rubbers – ASTM G21 and ISO 846 Comprehensive Evaluation

• Standard mold resistance test for polymeric materials (ASTM G21 / ISO 846) – We prepare specimens (50×50 mm) by cleaning the surface with isopropanol and placing them on a sterile nutrient‑salt agar. The specimens are then inoculated with a mixed fungal spore suspension of Aspergillus niger, Penicillium pinophilum, Chaetomium globosum, Trichoderma virens, and Aureobasidium pullulans (as per ASTM G21). The plates are incubated at 28±1 °C and 85‑90 % RH for a minimum of 28 days. The extent of fungal growth on the polymer surface is rated on a 0‑4 scale. A rating of 0 (no growth) or 1 (growth covering < 10 % of the surface) is typically required for Brazilian automotive and electronic applications.
• Biodegradation assessment of polymer compounds (ISO 846 Method B) – For evaluating changes in mechanical properties, we apply the fungal inoculum to the specimen surface and incubate for 12 weeks. After incubation, we measure the tensile strength, elongation at break, and impact resistance (Izod or Charpy) and compare them to unexposed control specimens. A retention of less than 80 % of the original mechanical strength is considered a failure.
• Weight loss measurement and surface degradation analysis – We carefully clean the incubated specimens to remove surface growth and measure the dry weight. The weight loss percentage is calculated; a loss greater than 1 % indicates significant polymer degradation. We also examine the surface by FTIR spectroscopy to detect any chemical changes (e.g., oxidation or hydrolysis) that are indicative of fungal attack.
• Effect of plasticisers and additives on mold susceptibility – We test polymer formulations with and without antifungal additives (e.g., zinc pyrithione, silver nanoparticles). The difference in mold rating and weight loss between the two formulations quantifies the effectiveness of the additive and helps Brazilian compounders optimise their recipes.

Electronic Assemblies and Electrical Components – Fungal Growth and Electrical Performance

• Mold growth on printed circuit boards and conformal coatings (IEC 60068‑2‑10) – We mount PCBs with assembled components and different conformal coating types in a controlled environmental chamber at 28‑30 °C and 90‑95 % RH. The specimens are inoculated with a fungal spore suspension (Aspergillus, Penicillium, Chaetomium species) and incubated for 28 days. After exposure, we inspect for hyphae growth between conductive traces and on component leads. We also measure the insulation resistance (ASTM D257) and perform a dielectric withstand test (500 V DC) to verify that the fungal growth has not caused short circuits or leakage currents. Any significant decrease in insulation resistance (e.g., below 100 MΩ) or leakage current above 10 µA is reported as a failure.
• Fungal growth on potting compounds and encapsulation materials – For electronic modules (sensors, controllers) that are fully encapsulated, we test the cured potting material (epoxy, silicone, polyurethane) following ASTM G21. We also evaluate the adhesion of the potting compound to the metal leads before and after mold exposure; a reduction in adhesive strength > 20 % may compromise the integrity of the electronic assembly in Brazilian outdoor and industrial environments.
• Corrosion of metallic contacts induced by fungal metabolites – We examine the metallic contact surfaces (copper, gold‑plated, tin) for any discolouration or corrosion products after mold exposure. We analyse the products using SEM/EDS to identify the presence of organic acids produced by fungi, which could lead to fretting corrosion. The extent of corrosion is rated and reported.
• Wire and cable insulation fungus test (IEC 60811‑402 adapted) – For cable insulation, we apply the mold test on cable sections and measure the elongation at break of the insulation after exposure. A retention of less than 70 % is considered a failure, which is important for Brazilian telecommunications and power cable applications.

Report Acceptance & Compliance with Brazilian Regulatory and Industry Standards

All mold growth tests described above are conducted under our ISO/IEC 17025:2017 accreditation, using certified fungal strains (available from ATCC or equivalent culture collections), controlled environmental chambers (temperature stability ±0.5 °C, humidity ±2 % RH), and calibrated instruments for mechanical and electrical testing. Our final test reports include: a complete description of the test method and reference standard, identification of fungal strains used, inoculation concentration and procedure, incubation conditions (temperature, RH, duration), a rating scale and results for each specimen (visual growth rating, staining, mechanical/electrical property retention), photographic documentation showing the specimens before and after the test, and a clear pass/fail verdict against the specified acceptance criteria (e.g., ASTM G21 rating ≤ 1 for automotive materials). We also provide an uncertainty statement for property measurements (tensile strength, electrical resistance). These reports are widely accepted by INMETRO for product safety certification of electronics, furniture, and construction materials, by ANVISA for medical device and pharmaceutical packaging approval, by ABNT for normative compliance, and by Brazilian importers and retailers for supplier qualification. Bilingual (Portuguese/English) versions are available to facilitate submissions to regulatory bodies and to support your internal quality and procurement teams. With our rigorous mold growth testing, you can confidently verify that your materials and products resist fungal colonisation, ensuring long‑term performance, aesthetics, and safety in Brazil's challenging humid environments.