Methods for Identifying and Inspecting Glass Mold

Visual inspection is the simplest and most practical method. Under strong light, place the sample in both reflected and transmitted light to observe whether there are spots or haze on the glass surface. These spots or haze cannot be wiped off with a cloth or water. If the above phenomena occur, it indicates that the sample has already become moldy.

II. Manifestations of Glass Mold

White haze/white spots: The mildest form of mold on the glass surface, caused by storage time, air humidity, or glass quality issues.

Rainbow patterns: If white haze/spots persist untreated, rainbow patterns may form. At this stage, mold remains only on the glass surface without penetrating into the glass.

Sulfur damage: While similar in appearance to mild mold, alkaline mold components have already corroded into the glass interior, representing severe mold.

Paper-like marks: Similar to sulfur damage, mold exists both externally and internally—also classified as severe mold.

III. Causes of Glass Mold

Water and moisture are key factors in glass mold formation. Without water, glass will not mold. If water on glass is promptly cleaned, mold will not develop.

Mold generally results from the combined action of glass, water, and atmospheric CO₂. Water or moisture lingering on the glass surface reacts with CO₂ in the air, inevitably leading to mold.

Temperature affects the rate of mold formation. Higher temperatures increase the likelihood of glass molding. For every 10°C rise, the rate of mold formation accelerates approximately threefold.

Glass composition is the fundamental condition for mold susceptibility. Generally, the higher the content of water-soluble Na and K raw materials in the glass formulation, the more prone the glass is to molding.

IV. Prevention Measures

Water and Moisture Protection: Preventing water and moisture exposure during storage and transportation is critical to avoid glass mold. After glass comes into contact with water, it should be cleaned and used as soon as possible. Glass is best stacked in dry areas.

Storage Practices: Separate glass sheets during storage. For long-term storage, it is advisable to apply anti-mold powder to the glass surface. For sealed packaging, desiccants should be placed inside.

Tin Side Facing Outward: In float glass, the tin side (formed during the floating process) develops a thin layer of tin oxide due to tin penetration. This tin oxide layer provides some resistance to mold. Therefore, in insulating glass units, the tin side is typically oriented toward the exterior of the air gap.