🧽 How to clean moldy tile gaps to make them white in Hong Kong

Hong Kong's weather is humid, especially in bathrooms and kitchens where there is constant moisture. This is where gaps in tiles are most likely to appear:

• Black mold spots🦠
• Yellowish-brown stains
• Musty smell 😖

This black mold not only affects appearance but can also release mold spores, causing allergies and respiratory problems. This article will teach you how to restore your grout to its pristine whiteness with a three-step process: deep bleaching, physical cleaning, and long-term mold control .

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1️⃣ Why do Hong Kong tile joints get moldy? 🔍

• High humidity 🌧️ → Hong Kong's average humidity is 70-90%, which allows mold to grow quickly.
• The gap material is porous → the caulk easily absorbs water, becoming a breeding ground for mold.
• Insufficient ventilation 🚪 → Most bathrooms in small units have no windows, making it difficult for moisture to escape.
• Infrequent cleaning → Water and soap stains accumulate, providing nutrients for mold.

💡Let me tell you : Once mold has penetrated deep into the caulk, it cannot be wiped off the surface. A two-pronged approach of "chemical penetration" and "physical scrubbing" is required to be effective.

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2️⃣ Preparation before cleaning🧰

• Bleach (chlorine bleach) or mold remover (containing sodium hypochlorite)
• Spray can (chemical resistant)
• Old toothbrush/stiff-bristled crevice brush
• Kitchen paper/cotton strips
• Gloves and masks
• clean water bucket
• microfiber cloth

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3️⃣ Deep Cleansing Process🧼

Step 1: Surface Cleaning

1. Use clean water to wash away dust and soap stains on the surface of the gap.
2. Wipe dry with a rag to prevent dust from affecting the penetration of bleach.

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Step 2: Bleaching to remove mildew (core step)

Method A – Direct bleach spray

1. Dilute bleach with water in a 1:1 ratio and pour into a spray bottle.
2. Spray evenly on the moldy gaps, making sure they are completely wet.
3. Let it sit for 15-30 minutes (up to 1 hour in severe cases).

Method B – Bleach with Paper Towel

1. Soak kitchen paper or cotton strips in bleach and apply them to the moldy seams.
2. This will allow the bleach to work longer and prevent it from running away.
3. Apply for 30 minutes to 2 hours for noticeable results.

💡Editor 's experience : Most mold in the gaps of Hong Kong bathrooms is stubborn. Applying bleach paper is more effective than spraying directly because the liquid can penetrate for a long time.

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Step 3: Physical scrubbing

1. Use a stiff-bristled brush (a toothbrush will also work) to scrub back and forth along the gaps.
2. Brush the sunken areas a few more times to remove the dead mold.
3. If you encounter any black spots in the corners, you can use the tip of a toothpick to gently pick out the black spots.

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Step 4: Rinse and dry

1. Rinse off any bleach residue with plenty of water.
2. Pat dry with a cloth to keep the caulking dry.

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4️⃣ Special Notes for Hong Kong📍

• Windowless bathroom : Be sure to turn on the exhaust fan when cleaning and wear a mask throughout the process to reduce the inhalation of chlorine.
• Severe mold in the gaps of old buildings : Dark shadows may still remain after bleaching because the mold has penetrated deep into the caulk. It is recommended to re-caulk the gaps.
• Colored caulk : Bleach may lighten the color, so test it in an inconspicuous area first.

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5️⃣ Long-term anti-mildew method🛡

• Scrape water after each shower → Use a glass scraper to scrape away water droplets on the wall.
• Spray anti-mildew agent regularly → Spray the gaps once every 1-2 weeks (transparent anti-mildew coating is available on the market).
• Maintain good ventilation → Turn on the exhaust fan for at least 30 minutes after showering.
• Use less soap bars → Soap stains can become nutrients for mold, so it is recommended to use shower gel instead.

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📌 Editor's Summary

To restore the whiteness of the tile gaps:

1. Apply bleach to moldy seams for a long time (penetration and sterilization)
2. Physical removal with a stiff brush (to remove dead mold)
3. Rinse + keep dry (to prevent regrowth)

💬 I've personally tested it and found that using the "bleach solution for 1 hour + hard-bristle brush" method can make even 2 years of mold and mildew look as white as newly renovated. The results are very satisfactory✨.
However, if the mold has penetrated deeper, it is best to re-caulk to maintain the beauty of the bathroom in the long term.