‘Mold’, Mildew and Fungi Basics and Problems

Last month we talked about paperless drywall – a substrate which promises superior water and mold resistance. This time around, we continue our educational series with a look a more detailed look at mold and mildew. Paint formulators help to navigate and minimize failures due to mold and mildew by incorporating the right additives as well as optimizing the binder or latex choice for a give application. As an example, today we see clear choices for Kitchen and Bath paints – these are paints with premium 100% Acrylic technology with the appropriate additives to maximize cleanability and minimize failures due to moisture (including mold and mildew), respectively. In this newsletter we highlight conditions that tend to increase likelihood of fungal growth and show a quick example to demonstrate how inclusion of a biocide in the paint can significantly boost resistance to microorganism growth on the painted surface.

What are Mold, Mildew and Fungi?

These are terms commonly referred to a group of microorganisms that are essentially ‘plants’ that lack Chlorophyll and hence can not photosynthesize their own food. They are saprophytic in nature and are scavengers – meaning they live on organic food that is prepared already for them, unlike algae which are lower forms of plants that are green due presence of Chlorophyll and are capable of photosynthesis.

The terms Mold, Mildew and Fungi are interchangeably used in common reference, however the class of microorganism specifically are to be referred to as Fungus or (Fungi (Pleural). “Mold” and “Mildew” are terms describing the appearance of the fungi on materials. For example when fungi appear “cottony” (example on bread) we refer to them as MOLD or MOLDY, and when there are patches with black soot like appearance of growth, it is referred a “MILDEW”. Mold and Mildew are essentially FUNGI.

Molds and fungi can be found both indoors and outdoors. No one knows how many species of fungi exist but estimates range from tens of thousands to perhaps three hundred thousand or more. Molds grow best in warm, damp, and humid conditions, and spread and reproduce by making spores. Mold spores can survive harsh environmental conditions, such as dry conditions that do not support normal mold growth. Indoors they can be found where humidity levels are high, such as basements or showers.

Some of the common indoor molds reported are Penicillium sp, Aspergillus sp, Cladosporium sp.,and Alternaria sp. Most of these belong to a class of Fungi known as Deutereomycetes or Fungi Imperfectii. Their primary mode of survival is by producing spores. Most of these fungi can be identified by microscopic observation of their spore types. They are distinguished by their colonies, and spore size and shape.

Root causes for Indoor Mold Problems can be attributed to some of the following reasons:

• Moving away from conventional construction materials that are resistant to biodeterioration (eg.) concrete, brick, stone, hard plaster etc.
• More biodegradable materials of construction in modern buildings such as paper (cellulose) based materials like wall papers, dry-walls , wood and wood-composites etc
• Buildings without proper aeration or ventilation
• Neglected building leaks and trapped moisture between walls
• Chronic wetting and dampness of susceptible building materials are ideal for mold growth.

Microscopic observation of Aspergillus and Penicillium spore bearing structures, Sporangia.

Today’s quality paints are routinely optimized to reduce the impact of mildewcide growth on substrates. The figure below shows how simple incorporation of a mildewcide (Rozone 2000™) in a fully formulated paint can significantly boost the mildewcide resistance (of a coating on drywall). Note that the panel labeled “Blank” contains no mildewcide and shows significant mildew growth.