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Tennis Court Paint, Tennis Court Resurfacing, Tennis Court Surfaces

When Is It Too Cold To Apply Tennis Court Surfaces?

When is it too cold to apply tennis court surfaces?  The quick and direct answer is:  It must be 50 degrees Fahrenheit (10 Celsius) and rising during application, and for at least 24 hours after.  This is very important to ensure curing of the 100% acrylic latex binder.

My tennis court coatings were dry, why is it failing?

As explained in a previous article, there is a difference between drying and curing.  The coating must dry first, which means the water in the paint evaporates.  This leaves all of the coating molecules, which are unconnected.  It looks normal to the naked eye after drying.  However, the particles are not melted together or coalesced.  If the temperatures fall below the recommended range and the coating gets wet from dew or precipitation, it can be easily damaged.

Tennis Court Coating Failure
Tennis court coating failure from improper curing, during cold temperatures.

Application During Marginal Temperatures

You have to be very careful when the temperatures are close to the edge.  As a general rule of thumb, don’t even think about applying tennis court coatings when the nighttime lows are forecast to be below 50 Fahrenheit / 10 Celsius.  Here are some other important risk factors to consider when temperatures are marginal:

  • Apply coatings very early in the day, just after dew has dried.
  • Don’t apply much later than early afternoon.
  • Sunshine is very important to drying and warmth of the pavement.  Shade can prevent drying of coatings for many hours.
  • Make sure to measure ambient air temperature, as well as pavement temperature.  The ground temperature is usually colder than air temperature during spring and fall.
    Measuring Pavement Temperature
    Infrared Thermometer for measuring surface temperature
  • High humidity slows down drying, and coatings must dry before they start to cure.
  • White lines reflect sunlight and are usually the first coating to fail if not properly cured.

Completing the surfacing process in cold weather

What happens if you start a tennis or sports court resurfacing project, and you run out of good weather part-way through?  No worries, you can wait until next spring/summer to finish the job.  It’s not worth risking failure and having a major cleanup on your plate.  No matter what stage of the coating process you are in, it can wait until the weather is right.

Tennis Court Surfaces

Drying Vs Curing | Tennis Court Surfaces & Paint

One of the most misunderstood topics and frequently asked questions are,  “what is the difference between drying and curing”  when it comes to tennis court paint and coatings.

Acrylic sport coatings are water-based, and latex is the binder or “glue” that adheres to the pavement or existing acrylic surface.  The binder also locks in all of the components of the coating system, like pigments, sand, and other proprietary ingredients. Water is the vehicle that thins the coating solids so that application by squeegee can be achieved.  Once the coating is applied, the water evaporates leaving the solids of the coating in a consistent film.  This evaporation is “drying“.

At this point, the film solids are dry.  They can even be walked on without a problem. However, all of the components of the coating are not entirely connected and bonded in a strong film.  In order for the coating components to properly coalesce, or “melt”  together,  it is important that the film remain mostly dry and in temperatures above 50° Fahrenheit.  This is especially important within the first 24 hours.  This is “curing“.

If the coating is not allowed to achieve this initial cure, the components like sand and pigment can wash or roll out the film can fall apart to varying degrees.  The level of damage or failure depends on how marginal the cure.

Tennis Court Curing Failure
Tennis Court Curing Failure

Many coating and paint specifications include the statement “product shall be applied when temperatures are 50° and rising”.  This means start coating in the morning when the temperatures are at least 50° and getting warmer, not late afternoon or evening when temps are dropping.

Remember, the coating must dry before it can begin to cure.  Starting application late in the day puts the film at risk of dew and cooler nighttime temperatures. A good rule of thumb is to avoid acrylic paint and coating application on days when the nighttime lows are forecasted to drop below 50°.  If the daytime highs are not very warm and it is cloudy, or the courts are heavily shaded, you also need to take that into consideration.  The shade will increase the drying time and affect the temperature of the court surface.  These factors affect drying and curing.

If you are forced to push the application on marginal days, you may want to use an infrared thermometer to check the surface temperature.  Pavement absorbs and holds cold for longer than most people think. In Spring and Fall, the sun is further away and not as intense. The pavement surface isn’t able to warm up as quickly as it does in the summer.

If you are a contractor and your customer is pushing you to apply when the temperature and weather is not within acceptable range, make sure to provide them with a copy of the coating manufacturer’s specifications and ask to reschedule application when conditions allow.