How does polyurethane sealant differ from silicone?

Polyurethane bonds structurally, takes paint and has higher mechanical strength. Silicone is more flexible and more resistant to water and UV, but will not hold paint and bonds less strongly.

Can acrylic sealant be used outdoors?

Not in moving facade joints — it cannot take the movement and will part. It can serve in sheltered, static cracks, but its proper place is indoors.

What is a siliconised sealant?

An acrylic-based sealant with silicone added to raise its flexibility. It keeps acrylic's paintability while flexing more than pure acrylic, and is common around timber frames and interior joints.

Why choose sausages over cartridges?

A 600 ml foil sausage leaves far less packaging waste for the same volume and costs less per litre. It needs a sausage gun, which makes it worthwhile for crews working continuously.

When can a sealant be painted over?

Polyurethane must cure fully first; paint applied early cracks as the joint moves. Acrylic can be painted shortly after the surface has dried.

How does fireplace sealant differ?

It is formulated to survive high temperatures and is generally not painted. Ordinary sealants break down at those temperatures, so fireplaces, flues and oven surrounds take a high-temperature product only.

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Sealants & Acrylics

A sealant does more than close a joint: it absorbs the building's movement, and whether it can be painted depends on its chemistry. This page covers the difference between polyurethane, acrylic and siliconised sealants, cartridge against sausage, and what movement capability means. The catalogue holds 25 products.

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Three sealants, three jobs

Sealants divide by chemistry, and that decides both durability and whether paint will hold.

Type	Movement	Paintable?	Where
Polyurethane	High	Yes, once cured	Facade joints, precast, vehicles, floor joints
Acrylic	Low	Yes	Interior cracks, around frames, skirting
Siliconised	Medium	Yes	Timber frames, interior joints, repairs
Fireplace sealant	Low	No	Fireplaces, flues, high-temperature points

Cartridge or sausage?

The 280-310 ml cartridge runs in a standard gun and suits occasional work. A 600 ml foil sausage leaves far less packaging waste for the same volume and costs less per litre, but needs a sausage gun.

For crews working continuously the sausage is the clear saving on both cost and waste; for a few cartridges a year, the cartridge is enough.

Colour and paint

Sealants come in white, grey, anthracite (RAL 7016), black and timber shades; choosing the right colour on a visible joint removes the need to paint at all. Where a polyurethane joint will be painted, let it cure fully first or the paint will crack.

Remember that paint does not hold on silicone: a "siliconised" sealant is acrylic-based and takes paint, while pure silicone does not.

Frequently Asked Questions

How does polyurethane sealant differ from silicone?
Polyurethane bonds structurally, takes paint and has higher mechanical strength. Silicone is more flexible and more resistant to water and UV, but will not hold paint and bonds less strongly.
Can acrylic sealant be used outdoors?
Not in moving facade joints — it cannot take the movement and will part. It can serve in sheltered, static cracks, but its proper place is indoors.
What is a siliconised sealant?
An acrylic-based sealant with silicone added to raise its flexibility. It keeps acrylic's paintability while flexing more than pure acrylic, and is common around timber frames and interior joints.
Why choose sausages over cartridges?
A 600 ml foil sausage leaves far less packaging waste for the same volume and costs less per litre. It needs a sausage gun, which makes it worthwhile for crews working continuously.
When can a sealant be painted over?
Polyurethane must cure fully first; paint applied early cracks as the joint moves. Acrylic can be painted shortly after the surface has dried.
How does fireplace sealant differ?
It is formulated to survive high temperatures and is generally not painted. Ordinary sealants break down at those temperatures, so fireplaces, flues and oven surrounds take a high-temperature product only.