Polysiloxane / Silicone

For many years the most widely specified paint system for bridges and marine applications has been a three-coat system consisting of a zinc-rich primer, an epoxy midcoat and a polyurethane topcoat. Recently FEVE, fluoroethylene vinyl ether fluoropolymers have been an alternative for the polyurethane topcoat. Another topcoat alternative for this demanding application is polysiloxane and it is a highly effective material for architectural applications as well.

This new siloxane chemistry results in a finish that is durable and corrosion resistant with much lower VOC levels than polyurethane and quicker drying times.

Dow Corning Allguard® Silicone Elastomeric Coating

An issue with silicone sealants, the material used most in building envelope joints, is the fact that acrylics and other paints won’t adhere to it. Dow Allguard does adhere to silicone sealants.

Dow AllGuard Product Data Sheet

Contractors Scope of Work — Scope of Work by JVS Building Services for Sealant Restoration (Sect. 2.1), Dow AllGuard® Polysiloxane Coating (Sect. 2.2) and Other Services

Before Application of Dow AllGuard® Polysiloxane Coating, and After

Norfolk Virginia Office Building Before and After Application of Dow AllGuard Polysiloxane Coating — Norfolk, Virginia Office Building Before and After Application of Dow AllGuard® Polysiloxane Coating (photo © JVS Building Services, LLC & Rob Crimmins)

Jimmie Davis Bridge Coating Project

This Durability + Design Magazine December 2014 article details the plan to paint a bridge built in 1968 over the Red River between Shreveport, Louisiana and Bossier City. The project will include cleaning and recoating all structural steel surfaces. Work will include abrasive blast-cleaning to a Near White finish (SSPC-SP 10) and recoating with a zinc-based, three-coat paint system (epoxy primer, epoxy intermediate, and polyurethane or polysiloxane finish).

Polysiloxanes vs Polyurethanes Epoxy Siloxanes and NISO (Acrylic/Acrylic or Acrylic/Epoxy)

For many years the most widely specified paint system for bridges and marine applications has been a three-coat system consisting of a zinc-rich primer, an epoxy midcoat and a polyurethane topcoat. Recently FEVE, fluoroethylene vinyl ether fluoropolymers have been an alternative for the polyurethane topcoat. This paper compares another topcoat alternative, Polysiloxane, to polyurethane.

This new siloxane chemistry results in a finish that is durable and corrosion resistant with much lower VOC levels than polyurethane and quicker drying times.

Selecting Polysiloxane Topcoats

June 2013 Design+Durability Magazine Article