Both are silicone. The difference is the chemistry they release as they cure, and that decides where you can use them.
Acetoxy (acetic) cure
Releases acetic acid as it cures — the sharp vinegar smell. It is fast, cheap, and sticks well to glass and glazed tile.
Do not use it on:
- Bare metals — aluminium, galvanised steel, copper, brass, mirror backing — the acid corrodes them and the bond fails.
- Cementitious surfaces — concrete, mortar, natural stone, fibre-cement — it reacts with the alkalinity and does not adhere.
- Enclosed joints where the acid cannot vent, and near sensitive electronics.
Keep acetoxy for glass-to-glass joints, sanitaryware, and internal tiled areas.
Neutral (oxime or alkoxy) cure
Releases neutral by-products and a mild odour. It sticks to almost everything used in facades — coated aluminium, uPVC, concrete, stone, most plastics — without corroding or staining.
Use neutral cure for:
- All perimeter sealing of windows and doors.
- Panel-to-panel and expansion joints.
- Anything touching metal, stone or concrete.
- Structural and weather joints on a glazed facade (with the correct grade).
On site
If you are not sure what the joint touches, use neutral cure — it is the safe default and the small extra cost is nothing against a failed joint. Ask us for the neutral grade rated for the substrate and the movement.
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