Sealants

[DIYWell]

I hope someone can educate me.

I want to seal the gap between brickwork and a new UPVC frame. (Previous frame was wooden and sealed with something that's hardened over the years.)

Frame sealant: Matt and overpaintable
Silicon sealant: Shiny and can't easily be painted

Must be more of a difference between the two surely?

 

[robinbanks]

What is your question?

 

[DIYWell]

What's the difference between silicon and frame sealants?

 

[Swwils]

Silicone sealants are polymers that are primarily derived from siloxane monomers. They're characterized by a repeating Si-O backbone. Frame sealants are typically based on acrylic or sometimes polyurethane polymers.

They both have different jobs, properties and applications.

 

[DIYWell]

They both have different jobs, properties and applications.

And what are those different jobs, properties and applications?

 

[Swwils]

Silicone Sealants

Molecular Structure: Primarily derived from siloxane monomers, silicone sealants are characterized by a repeating Si-O backbone.

Properties:
Thermal Stability: Exceptional temperature resistance, functioning well across a wide range (from -50°C to 150°C).
Weather Resistance: Highly resistant to ultraviolet (UV) radiation, ozone, and external environmental conditions.
Flexibility: Excellent elastic recovery, allowing for movement and flexibility in structures.
Adhesion: Bonds well to a variety of substrates, including glass, metal, and certain plastics.
Chemical Resistance: Resistant to moisture, mildew, and many chemicals.

Applications: Used in a wide range of construction and industrial applications, such as glazing, window and door perimeters, and other building joints.

Frame Sealants (Acrylic/Polyurethane Based)

Molecular Structure: Typically derived from acrylic or polyurethane polymers.

Properties:
Paintability: Acrylic-based frame sealants can be painted over, allowing for a seamless blend with adjacent surfaces.
Durability: Polyurethane offers higher durability and strength compared to acrylic.
Adhesion: Both offer good adhesion, but polyurethane has a broader substrate range.
Shrinkage: Acrylic sealants may shrink more upon curing than polyurethanes.
Weathering: Polyurethane sealants generally offer better weather resistance than acrylics.

Applications: Specifically designed for sealing window and door frames, and other joinery applications. They are also used in gap-filling, internal skirting, and areas where paintability is required