How to Remove Bamboo Mold
The forming of mold, spores and mildew on the surface of bamboo canes is not uncommon, especially when bamboo is not 100% dry, or when products are shipped internationally in ocean freight containers.
Surface mold on bamboo products will only occur once, maybe twice until excessive moisture content inside the bamboo canes is completely evaporated.
Bamboo species such as Phyllostachys aurea, are often treated with a flame torch (heat treatment) and thicker bamboos such as Guadua angustifolia are cured with a boron solution.
The heat treatment is applied to fresh, green bamboo which leaves more moisture content inside the canes after the treatment opposed to air dried (boron treatment) bamboo. That's why some finished bamboo products are initially more sensitive to mold forming.
However, even well treated and dry bamboo poles may suffer spectacular surface mold. If an ocean freight container is loaded in a tropical environment, where the air is warm and humid, then shipped to an environment where temperatures are far cooler, the cargo may have experienced a phenomenon known as “cargo sweat” or “container rain”. Long transit times (often 30 days or more) and extreme temperature variations may cause condensation inside the container that triggers the growth of surface mold on bamboo.
What causes Fungus to Grow on Bamboo?
- Carbohydrates: Fungus originate from very fine, air-borne spores present in fruit bodies and cause biological degradation of bamboo. They nourish from the starch and other carbohydrates (sugar) that are present in bamboo culms. At an advanced stage, their damage will show on the surface of the bamboo.
- Oxygen: Just as almost any other living thing on this planet, fungus needs to breath. Limiting that supply of oxygen will retard their growth. Some fungi though, can survive on very low levels of Oxygen as long as their is a high presence of moisture.
- Moisture content: Fungi love humid environments! Moisture levels of 40 to 80% are ideal for their rapid growth.
- Temperature: Fungus feel most comfortable at temperatures between 25°C to 35°C.
What Types of Fungi Attack Bamboo?
- Surface Molds: These bamboo molds grow on the surface and at the cross-ends of bamboo culms. Although they look spectacular, they have no influence on the strength of the bamboo and can be wiped off easily.
- Stain Fungi: These bamboo fungi can penetrate round bamboos from cross cut ends as well as from cuts at the nodes after removal of the branches. Attack is indicated by shades of blue/grayish-black discoloration on the surface in the form of spots and streaks. It reduces the aesthetic appearance but does not affect the strength properties of bamboo (except in severe cases of attack).
- Decay Fungi: These bamboo fungi cause the most serious kind of damage and grow within the lumen of the cells. The enzymes either decompose only the cellulose and hemicellulose leaving behind the lignin leading to brown rot, or they decompose lignin leading to white rot (white rot is more common in bamboo than brown rot). Early decay is difficult to detect. Even before slight color change or weight loss becomes apparent, the strength properties are much reduced, in particular the impact and bending strength. Early damage can be characterized by dampness in bamboo. At later stages of deterioration the culm is soft to the touch and may be only a fibrous or powdery mass.
How to Clean Mold from Bamboo?
The most effective way to instantly remove mold on bamboo is a commercial product called Mold Armor FG502. Alternative methods with lemon oil or vinegar as described below could also do the trick.
Remove bamboo mold, white spores and mildew with a soft brush and clean up the area with a damp cloth. Use lemon oil or a solution of vinegar and water to remove the mold.
For bamboo furniture it is recommended to apply 3 coats of polyurethane after the mold is removed. This can be time consuming but will ensure the conservation of the furniture. Make sure though, to first clean the furniture with turpentine and to dry it out completely. If you don't, mold might grow underneath the polyurethane finish and cause blisters.