Article 2: Specialist preparation of Polyurea
Over the previous months CSC Services have been focussed on conveying the range of applications and adhesion characteristics of Polyurea coating.
In this series of articles Mark Lemon, Managing Director of CSC Services looks at the important reasons why approved and trained installers are required for such technology.
Preparation of Substrate
All too often coatings will fail due to incorrect substrate surface preparation. Dirt, grease, dust and other surface latents will form a barrier between the substrate and coating to be applied which means there is no mechanical bond present.
The preparation of the surfaces to which the system will be applied is of fundamental importance for its final success. Preparation will depend on several factors that can be summarised as follows:
- Type of substrate
- State of substrate
- Coating cycle
- Total Loads
The importance of preparation is a key area outlined in the Polyurea Development Association Europe‘s most recent Code of Good Practice (2014). Preparation methods described include:
Grinding: this is a mechanical action performed with abrasive wheels, or abrasive paper (sanding) in order to remove laitance, dirt or other material from the crust of the surface.
Scarification: this is a mechanical action carried out by a rotating or non-rotating scarifier aimed at removing the surface crust from 3m-5m.
Milling: this is the mechanical action of a rotary cutter to achieve homogeneous and total removal to a constant thickness, regardless of the resistance of the substrate.
Shotblasting: this is the mechanical action of metallic granules propelled by special machines with a complete recirculation, separation and recovery of sandy and other materials, all dust free.
CSC Services specialise in Dustless Blasting. This is a dust free process in which all materials, shot media and old coatings when blasted from a surface are vacuumed back into the machine via a hose attached to the inside of the blast nozzle. This process is used in areas which might house sensitive equipment, machinery or where dust might cause problems.
UHP Jetting or High Pressure Water Jetting can be used in the demolition of structures or materials such as concrete and masonry. This has distinct advantages over conventional methods. The risk of fire or explosion is removed and dust is controlled. Ultra High Pressure Water Jetting (UHP Jetting) is also used to remove old coatings which lower pressures cannot. Coatings needing Ultra High Pressure Water jetter removal might include bitumen, epoxy, limpetite and polyurethane.
Join us for our next article which will explore the three key variables associated with the application of polyurea coating, and examine why applicators should fully understand the dynamics of pressure, temperature and flow to ensure correct use of the specialist application equipment.