Technical – Constraints & Considerations

Technical Information - Painting Constraints & Considerations

Painting Constraints & Considerations

  • Spraying can only be carried out in fine, dry weather with little wind.
  • Colour Coating is normally undertaken during the Warmer Months.
Spraying Colour Coat onto Tennis Court
Weather & Temperature

Painting outdoors is obviously, extremely weather dependent. It can only be carried out in fine, dry weather with little wind.
After being sprayed onto the surface the paint dries to the stage where it is touch dry, and at this stage it starts its initial curing.

This can take between one and twelve hours, depending on;

  • Temperature
  • Humidity
  • Air movement

As a rule of thumb spraying is normally only undertaken during the period of British Summer Time.

Wet Weather

Colour Coatings cannot be applied to an excessively damp surface or obviously when it is raining.

Programming work in the UK climate can sometimes be very difficult and delays can occur. It is very helpful if the client can allow flexibility with access & working times. During any periods of unsettled weather we will communicate if delays are likely to occur.

Wind & Air Movement

In order for the coating to cure effectively air movement over the surface is necessary to allow the water within the coating to evaporate, this is more critical when applying them indoors.

Strong winds, whilst being a benefit to the curing cycle can often cause problems with drift on to the surrounding fencing and also make the application of two tone surfaces more difficult with excessive masking required.

Temperature

The ideal application and curing temperature range is between 10ºC and 35ºC. This range should ideally be in place for the first 73 hours after the coating has been applied.

A drop in temperature below 5ºC will stop the curing cycle and therefore seriously affect the long term durability.

It is important to understand that whilst the ambient air temperature may be within this range, the surface temperature is most often lower than this as it’s temperature falls dramatically overnight.

The surface temperature affects the curing of the paint and that it should be the ground temperature that is measured not the air temperature – many sunny spring or autumn days have an air temperature above 10°C or 15°C whilst the ground temperature (and therefore the film temperature) remains at 2°C or 3°C.

Surface Preparation

Surface Cleanliness is extremely important if the Colour Coating is to adhere correctly. The area to be coated should be free from oil and dirt. Loose leaves and other detritus lying on the surface is normal and is swept or blown free by ourselves immediately prior to painting.

Re-Painting older existing courts or very dirty new courts will require Chemical Treatment and thorough Power Washing to remove moss, weeds and ingrained dirt prior to painting.

Macadam – New Surface
Paint coatings do not achieve good adhesion to newly laid macadam, the bitumen normally has a glossy finish; as it cures, the top layer hardens and it looses its sheen as the oils evaporate. It is at this stage that the court is normally considered suitable for spraying.

The time it takes for oxidation to occur will vary depending on the nature of the surface and the weather but it will normally take between two and three weeks in the summer and may take up to three months in the winter.

If a court is painted before the bitumen incorporated in the macadam has been allowed to harden adequately, the paint will cure satisfactorily but during periods of hot weather the bitumen below will soften. Foot traffic will break away the hard paint film leaving a black smear, often in the shape of a twisting sole or heel.

Method of Application

Method of Application
We apply paint or binders using Airless Sprayers, producing a uniform spray fan with feathered edges. This results in excellent coverage with minimal discernible lines on the painted surface.

Two coats of paint are applied, the second coat is applied at 90 degrees to the first to ensure an even finish with no patches.

Access to the Courts
Our Airless Paint Spraying Equipment is normally fixed on the rear of large 3.5 tonne vans.

The spray guns are fed with paint pumped through high pressure hoses running from the van to the courts.

Whilst we can extend the length of the hoses, we still require the van to be located nearby, with easy access for personnel working on the court.

Time Taken for Application
In good weather painting a standard court is achieved in a day. Where there is more than one court we may increase the manpower and number of spray guns to achieve this in 1-2 days.

During unsettled weather, two or more visits are commonplace to finish the courts.

Paint Curing Period
On completion of painting, the paint surface will be touch dry. The period of time necessary for the paint to fully harden is dependent on the ambient temperature.

Play can usually occur after 3 days but in low temperatures this can take up to 5 days.

Airless Sprayer

Airless Sprayers force fluid at high pressure through a small nozzle (spray tip). The tip size and pressure determines the material flow rate. The tip also creates the desired fan pattern.

Piston powered Airless Paint Sprayer develop the required pressure by driving a piston up and down. As the piston travels up it creates a vacuum sucking the paint up through the suction pipe, inlet valve and piston. When it travels down it forces the paint out through the outlet valve, through the hose and to the gun. Pressures will depend on many factors but will typically be between 2,500 and 5,500 psi.

When the spray gun trigger is pulled, paint emerges from the tip as a solid stream (sheet) at a high speed. When the solid stream hits the air, it becomes disrupted. This disruption breaks the fluid into fragments initially, then ultimately very small droplets that form the spray pattern.

Benefits of Airless Spray

  • Transfer efficiencies in the 60-70% range. High transfer efficiency means less waste, more product on the surface.
  • Fast application at excellent coverage rates, capable of applying thick coatings at high speed.
  • The ability to apply unthinned coatings. Airless sprayers can apply high-viscosity materials without excess thinning.
  • Excellent coverage of irregular surfaces.

Technical Information - Painting Constraints & Considerations