Mold Problem on M.D.F.

M.D.F. has wide usage in the woodworking industry. It is used a lot to make panels, boards, and any other flat product replacing the solid wood. As the engineering product, M.D.F. actually gives a lot of advantages instead of the solid wood. It is more uniform, more stable, and less expensive than a wooden plank. See our previous article: M.D.F. for furniture. But instead of his benefit, the M.D.F. also has some disadvantages. One of the disadvantages of M.D.F. is the high risk of getting a fungal problem.

M.D.F., or medium density fiberboard, is an engineering wood product that is made of wood fiber, wax and resin. The wood fiber, resin, and wax are heated and mixed evenly and then molded, forming certain thick boards. The melamine resin is layered at the M.D.F. surface that gives the smooth surface. The melamine resin is the coating layer at the M.D.F. surfaces that gives protection for the product. But naturally, the melamine resin also produces formaldehyde gas, which is considered harmful to human health. Since the 2000's, many countries have restricted the formaldehyde for their products. There are some regulations that also affect the woodworking product, including the M.D.F. product. Now the M.D.F. product must not emit formaldehyde gas exceeding a certain threshold to fulfill the environmental regulation law in many countries. 

 The fungi at the naked M.D.F.

The regulation forces the M.D.F manufacturer to reformulated the process of manufacturing M.D.F. They have to change the melamine resin to reduce its formaldehyde emission, and this condition also affects its protection properties. Now we found more issues about fungal problems at the M.D.F product than before 2000,s. The mold problem is more often found at the back panel of the woodworking products that use M.D.F. There are many mold and fungi problem issues found at the back panel of the top table, side panel, inside drawer, etc. 
The fungi problem is less found at faces that are well finished. The face panels that are layered by veneer, vinyl, decorative paper, or coated with thick film finish are usually away from the fungal attacked. The fungi or mold problem issues are commonly found at the unfinished M.D.F. or at the back panel as the unexposed part that is layered with thin coating or kept unfinished.
But, however, the presence of fungi even in the unexposed part will directly degrade the quality of the product. The fungi will ruin the product's appearance and make the product look bad. The fungi also potentially cause health problems because it will generate a dust spore that is spread throughout the entire room. 

 
Here are some actions that we can take to prevent and overcome fungal attacks on M.D.F.

• Clean the fungi at the surface

If we find the product has been infected by the fungi, then we need to clean the fungi. Wet the cloth with paint thinner or cleaning fluid, then wash and rub the surface until all fungi are removed. Make sure the liquid does not dissolve and ruin the finish layer. Let it dry, then scuff sand to the surface, then apply a coating layer to the surface. Add some anti-fungal additives to the coating to minimize the fungal problem for film coating. Make sure we apply enough thick coating to give enough protection to the product, but make sure we choose the proper finish according to how the product looks.

• Keep the product to be dry.

The wet and humid conditions are the major factors that prompted the fungus to grow. The wet surface is the ideal medium for fungi to grow. One of the best ways to avoid the fungi is to keep the product dry. Store the M.D.F. product in the air conditioning room or warm room to keep its moisture content under 10%. Keep the room to get good air circulation to keep the room fresh and dry.

• Apply good coating to the M.D.F. product. 

The M.D.F. is hygroscopic material. The open and naked M.D.F. will adjust its moisture content to its environmental air humidity. We can coat and paint the MDF surface to close the surface and reduce its hygroscopic properties. The coated M.D.F. will be more stable and safer from the fungus. The catalyzed coating, such as the PU or AC coating, will give better protection than the 1 component coating (NC or water-based). If necessary, we can add some more anti-fungal additive at the coating layer to give more protection from the fungal attack. 
The use of water-based coating must be carefully done. The water in the coting will increase the moisture content of the M.D.F. and finally lead to the fungi to grow. Make sure the day is hot and dry when we apply the water-based coating. If the weather is cold and humid, then we absolutely need an oven to control the drying process.