Tile grouting looks simple, but in practice, it involves a lot of know-how. Especially for homeowners trying it for the first time or workers new to the trade, overlooking small details can lead to a series of issues, such as the appearance of grout whitening.
Why does grout turn white? The whitening of the grout is not due to a color change in the sealant itself, but rather because, in low-temperature and high-humidity environments, the curing agent and the oxygen molecules in the epoxy resin react with water, forming a white salt-like substance. This substance gives off a frost-like effect, leading to the whitening of the grout.
The water involved in this chemical reaction may come from the following sources:
Moisture in the air
Residual water in the tile gaps
Condensation caused by temperature differences between the environment and the grout surface.
However, there's no need to worry too much. Once the grout is fully cured, it will not turn white again, even in humid or low-temperature environments.
Common causes of grout whitening:
Damp or low-temperature construction environment: For example, during prolonged rainy weather or when the humidity rises in certain seasons, moisture enters if doors and windows are not closed in time.
Un-dried tile gaps: If the tiles are laid recently or the construction area hasn't fully dried, especially in damp areas like bathrooms.
Condensation due to temperature differences: In low-temperature environments, using devices like a bathroom heater can create localized temperature differences, leading to condensation.
Cleaner residue: Using oxalic acid or strong alkaline substances to clean the tile gaps before construction.
How to avoid grout whitening:
Control the construction environment: Ensure the temperature is between 10°C and 30°C, and relative humidity is below 70% (use a thermometer and hygrometer or check the weather forecast).
Check the base for dryness: Before starting, ensure the tile gaps are completely dry, especially in areas where tiles were recently installed.
Avoid working in humid weather: Try to avoid construction during rainy days, high humidity, or the monsoon season. If necessary, use air conditioners or dehumidifiers to reduce humidity.
Use appropriate cleaning methods: Avoid using oxalic acid or strong alkaline cleaners for the tile gaps. By conducting the construction scientifically and paying close attention to the details, the grout effect will be more durable and aesthetically pleasing, saving you from having to redo the work later.
