Recommended application procedures Coatings in the BASF range are normally applied by brush, roller or airless spray.
The requirements for successful application, are the same for all types of coating, whether for industrial use or decorative purposes. The main points are listed below:
- Select the right product for the job
- Smooth substrate free of defects
- No sharp arrisses
- Good surface preparation
- Correct equipment for the application
- Trained operatives
- Substrate and ambient temperatures in the safe range
- Relative humidity acceptable
- Sufficient product to complete the job
Substrate preparation
Good surface preparation is a key factor in the durability and performance of any coating.
The type and extent of surface preparation will vary according to the requirements of the coatings "in service life". If a product is to protect the substrate from chemical attack, the coating must be entirely free of pinholes or any other defects that would allow the chemical to penetrate the coating. If the product is being used to provide dust proofing or abrasion resistance, then a few pinholes are unlikely to affect the long term performance.
Good surface preparation will help ensure that the selected coating will achieve its expected performance.
Surface preparation
Coatings subject to chemical attack - All concrete surfaces should be lightly grit blasted to remove all laitence and expose blowholes and other surface defects. Very high pressure water jetting is also suitable.
- Round off arrisses, and grind off surface projections to ensure a smooth substrate.
- Cut out and repair defective concrete.
- Using clean, oil free compressed air or high pressure water jetting with potable water, clean down the prepared surface.
- When the surface is clean and dry, use an epoxy filler, such as Concresive 2200 or a cementitious product, such as EMACO R303 to fill all blowholes, cracks and other defects.
- When using epoxy fillers, an alternative method is to apply a mist coat of coloured primer / sealer (which could be a diluted form of the protective coating) to highlight blowholes and other defects. As soon as the mist coat has dried, start applying the filler.
- When filling has been completed, rub the surface down to ensure a smooth finish.
- Ensure EMACO repairs are fully cured.
Coatings subject to traffic / abrasion - Initial surface preparation should be as (1) above but horizontal surfaces could be etched utilising a captive blasting machine or acid etching.
- When acid etching, great care must be taken to ensure that all traces of acid are washed away from the treated surface.
- Filling of surface defects will be as required, to achieve the finish and durability expected of the coating.
Cosmetic or aesthetic coatings Light duty coatings are often applied to concrete surfaces that have had minimal preparation. The adhesion of any coating to a substrate from which the laitance has not been removed will be poor compared to the same coating applied to a correctly prepared surface. If the surface of the concrete is weak, premature failure of the coating can be expected. Application
- Mix and apply the coating according to the recommendation of the technical data sheet and good application practice.
- Always apply two coats of the product, the second coat being applied at right angles to the first.
- Do not apply coatings if the humidity is likely to rise above a RH of 85% or the dew point is reached during application.
- Take note of overcoating times both minimum and maximum.
- Avoid coating surfaces that are exposed to direct sunlight at the time of application if the surface temperature is likely to rise above 40°C.
- Hot surfaces can cause flash setting and blistering, with a reduction in bond strength.