Silicone vs Acrylic Sealant: What’s The Difference?

If you’ve ever searched “silicone vs acrylic sealant” or “can I use silicone instead of acrylic?”, you’re not alone.

This is one of the most common DIY questions in Australia, and it’s also where most people get it wrong.

Using the wrong sealant won’t usually fail immediately. It’ll fail six months later. Cracks. Peeling. Mould. Water damage. Then you’re scraping it out and doing it again.

Let’s break it down properly.

The Simple Answer

• Silicone sealant is flexible, waterproof and ideal for wet areas.

• Acrylic sealant (gap filler) is paintable and ideal for interior cosmetic gaps.

That’s the high-level version.

Now let’s go deeper.

Flexibility: Which One Handles Movement Better?

Silicone Sealant

Silicone is highly flexible. It remains rubbery after curing and can stretch and compress without cracking.

That’s why it’s used in:

• Showers

• Around baths

• Around sinks

• Window frames

It handles thermal expansion and contraction extremely well.

Movement capability is often ±20% to ±25%, sometimes more depending on the product.

Acrylic Sealant

Acrylic sealant is far less flexible. It dries firm and can shrink slightly as it cures.

Movement rating is usually low, around ±5% to ±10%.

It’s designed for small interior gaps that don’t move much, like:

• Skirting boards

• Architraves

• Cornices

If the joint moves significantly, acrylic will crack.

Paintability: Can You Paint Over It?

This is where acrylic wins.

Acrylic Sealant

• Fully paintable

• Designed to be painted

• Can be lightly sanded once dry

If you’re prepping a room for painting and need to fill gaps, acrylic is what you want.

Silicone Sealant

• Not paintable

• Paint won’t stick

• Needs to be colour matched at purchase

If you apply silicone where you plan to paint, you’ll regret it.

Waterproofing: Which One Is Water Resistant?

Silicone Sealant

Silicone is completely waterproof once cured. It’s designed for constant water exposure.

If you’re searching:

• Best sealant for shower

• What sealant for bathroom?

• Can acrylic be used in wet areas?

The answer is silicone for wet areas.

Acrylic Sealant

Acrylic is water resistant to a degree but not waterproof long term. It softens with ongoing moisture exposure.

Using acrylic in a shower or around a bath will lead to:

• Cracking

• Peeling

• Mould growth

• Water getting behind tiles

Mould Resistance: Which One Is Better?

Silicone sealant formulated for kitchens and bathrooms contains mould inhibitors.

Acrylic does not offer long-term mould resistance in wet areas.

If you’re sealing:

• Shower corners

• Around sinks

• Splashbacks

Silicone is the safer choice.

Movement Rating Explained

You’ll often see something like “movement capability ±25%” on silicone.

Here’s what that means.

If a joint is 10mm wide:

• A ±25% sealant can stretch to 12.5mm

• Or compress to 7.5mm

Without tearing.

Silicone typically has a much higher movement rating than acrylic.

In Australian conditions, with heat, UV and big temperature swings, movement matters. Exterior window frames and wet area joints expand and contract constantly.

Acrylic simply isn’t designed for that, so most people opt for a Polyurethane sealant here. 

Where Silicone Fails

Silicone isn’t perfect.

It fails when:

• You try to paint over it

• You apply it to dirty or dusty surfaces

• You use acetic cure on sensitive metals or stone

• You use it in structural expansion joints designed for polyurethane

It also requires more careful application to get clean lines.

Where Acrylic Fails

Acrylic fails when:

• Used in showers or wet areas

• Used outdoors without proper exterior rating

• Applied to large moving joints

• Exposed to heavy water over time

It’s not designed for structural movement or waterproof sealing.

Silicone vs Acrylic Sealant Comparison Table

Here’s the side-by-side breakdown people are usually looking for.

So Which One Should You Use?

If you’re filling small interior trim gaps before painting → Acrylic sealant

If you’re sealing a shower, bath or sink → Silicone sealant

If water is involved, choose silicone.
If paint is involved, choose acrylic.

It’s that simple.

Final Thought

Most DIY sealant problems don’t happen because people can’t apply it neatly.

They happen because the wrong product was chosen at the start.

If you match the sealant to:

• Water exposure

• Movement

• Whether it needs to be painted

You’ll get a result that still looks good in three years, not just on day one.