Can I use acetic silicone on metal?

No. Acetic silicone releases acetic acid as it cures and corrodes metal. Use neutral cure silicone on metal, aluminium and zinc.

Why has my silicone yellowed?

Usually a product with low UV resistance used outdoors, or a chemical reaction with an unsuitable surface. Outdoors, choose a product that states UV resistance.

Can new silicone go over old?

No. New silicone will not bond to cured silicone; strip the old joint out completely, then clean and degrease the surface.

How do I slow mould growth in a bathroom?

Use a sanitary grade with a fungicide, keep water off it until it has cured, and ventilate. Mould usually grows in the soap residue on the silicone rather than in the silicone itself.

What temperature does heat silicone withstand?

It varies by product and is printed on the cartridge; the red gasket grades are formulated for engine and exhaust temperatures. Inside a fireplace, use a dedicated high-temperature sealant instead.

How long until silicone is fully cured?

The skin forms in minutes; full cure advances at roughly 2 mm of depth per day. In a deep joint that means several days, and temperature and humidity affect it directly.

Brand

Sort

Silicone Sealants

Silicone keeps its flexibility for years and resists water and UV — but where a given silicone can go depends on how it cures. This page explains the difference between acetic and neutral cure, the special-purpose grades, and the rules for applying them. The catalogue holds 28 products.

1–24 of 28 · page 1 / 2

Cure type: acetic and neutral

The by-product released during cure decides which surfaces a silicone belongs on. Acetic silicone gives off acetic acid — the source of the vinegar smell; it cures fast and grips non-porous surfaces very well. Neutral grades (oxime, alkoxy) are not corrosive.

Using acetic silicone on metal, concrete, marble or a mirror damages the surface: corrosion on metal, staining at the edges of marble, and breakdown of a mirror's backing.

Surface	Silicone	Why
Glass, ceramics, tile	Acetic	Best adhesion on non-porous surfaces
Aluminium, zinc, metal	Neutral	Acetic acid causes corrosion
Concrete, marble, natural stone	Neutral	Acetic acid attacks the surface and edges
Mirrors	Mirror silicone (neutral)	Leaves the backing intact
Aquariums	Aquarium silicone	No fungicide, safe for livestock
Exhausts, ovens, gaskets	Heat silicone	Withstands high temperatures

Special-purpose grades

Heat (gasket) silicone is made for engine gaskets and ovens and is usually red. Aquarium silicone leaves out the mould inhibitor found in ordinary sanitary grades, because that additive leaches into water and harms livestock.

Sanitary grades for bathrooms and kitchens carry the opposite requirement: a fungicide, precisely because they live in permanently damp air.

Application and cure

The surface must be dry, clean and free of grease; running new silicone over old without stripping it out is the most common cause of failure. Masking tape either side of the joint, removed straight after tooling, leaves a clean edge.

A skin forms within minutes; full cure takes days depending on thickness — around 2 mm of depth per day as a rule of thumb. Water on uncured silicone ruins adhesion, so leave a shower 24 hours before use.

Frequently Asked Questions

Can I use acetic silicone on metal?
No. Acetic silicone releases acetic acid as it cures and corrodes metal. Use neutral cure silicone on metal, aluminium and zinc.
Why has my silicone yellowed?
Usually a product with low UV resistance used outdoors, or a chemical reaction with an unsuitable surface. Outdoors, choose a product that states UV resistance.
Can new silicone go over old?
No. New silicone will not bond to cured silicone; strip the old joint out completely, then clean and degrease the surface.
How do I slow mould growth in a bathroom?
Use a sanitary grade with a fungicide, keep water off it until it has cured, and ventilate. Mould usually grows in the soap residue on the silicone rather than in the silicone itself.
What temperature does heat silicone withstand?
It varies by product and is printed on the cartridge; the red gasket grades are formulated for engine and exhaust temperatures. Inside a fireplace, use a dedicated high-temperature sealant instead.
How long until silicone is fully cured?
The skin forms in minutes; full cure advances at roughly 2 mm of depth per day. In a deep joint that means several days, and temperature and humidity affect it directly.