Neutral cure or acetic cure? How to choose a silicone sealant

Silicone sealants fall into two main types: neutral cure and acetic (acid) cure. They look much the same, but using the wrong one can damage materials or bond poorly.

1. The difference

Acetic cure silicone releases acetic acid as it cures, giving off a strong vinegar smell, and can corrode or bond poorly to aluminium, coated glass, metal and stone. Neutral cure silicone does not release acetic acid, has less odour and does not corrode building materials.

2. Windows, doors and curtain walls: use neutral cure

For aluminium windows and doors, glazing, aluminium curtain walls and stone joints, use a neutral cure silicone, such as WACKER TOPP weatherproofing sealant and LC909N (LE-RELAX is the sole Hong Kong distributor of WACKER), or KCC SL907 Premium glazing sealant.

3. Bathrooms and kitchens: use an anti-mould sealant

Bathrooms, toilets and kitchens stay damp and are prone to mould. KCC BIO-KORESEAL SL825 and SL825 Premium have an anti-fungal, anti-mould formula for these areas.

4. Application tips

• Clean the surface first: it must be dry and free of grease and dust.
• Check the application temperature: TOPP, for example, is suitable from 5°C to 40°C.
• TOPP, for example, is tack-free within about 10 minutes and fully cures in 7 to 14 days; avoid stress or water on the joint during this time.
• Match the colour to the frames: TOPP comes in champagne, white, grey, black and bronze.