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Airless Spraying Hints and Tips

These are some useful hints and tips when using an airless sprayer for roof coatings.

Click on a topic to see more:

Tip Size
Film Thickness
Distance
Cleaning the Nozzle
General Advice

Tip Size

There are many different tips out there available to use. This information will help you pick the right one.

There are various factors relating to choosing a tip:

  • Fan width
  • Orifice size
  • Maximum output
  • Type of paint
  • Type of surface
  • Tip wear

Fan width

The fan width controls how wide the application is. The wider it is, the faster the job will get done. However, people spray at different rates, so someone who sprays slowly could have a wider fan width than someone who sprays too fast, as they may not get a thick enough coat otherwise.

Orifice

The orifice size controls how much coating flows through the tip. A larger orifice should be used for heavier fluids, which included elastomeric roof coatings such as Fibroseal.

Maximum output

Choosing a tip also depends on what kind of machine you are using. Certain machines can only handle certain tips.

Tip wear

Tips don’t last forever, and as they wear down, the fan width reduces and the orifice size increases, meaning you waste material and it takes twice as long.

Using abrasive coatings, such as Fibroseal, will mean the tip will wear down quicker. Replacing the tip will be cheaper than continuing the job with a worn out tip, so make sure you replace them when needed.

Film Thickness

It is important to measure the thickness of the film to ensure you are applying the correct amount. This should be implemented for cost reasons, because if you are applying too thick a coating, it can be corrected before doing the whole roof and wasting the coating.

Using a wet film comb is the simplest way of measuring this. It also means that, because you can measure it while the coating is still wet, you can correct any mistakes then and there without having to wait for it to dry.

How to use a wet film comb

Hold the comb perpendicular to the surface that is coated.

Wait a few seconds until the teeth are wet, then remove.

The wet film thickness is worked out as being between the biggest value that is wet and the smallest value that is dry.

For example, if the biggest value that is wet is 6, and the smallest value that is not wet is 8, then the thickness is between 6 and 8.  

Distance

When spraying, you should make sure each stroke is the same distance away from the surface as the last. This will ensure an even coating. A distance of 6 to 12 inches is ideal.

Unclogging the Tip

If you get a blockage in the tip while spraying, it’s very easy to clean with Graco Reverse-A-Clean spray tips.

  • Lock gun trigger safety.
  • Twist RAC guard handle 180°
  • Unlock gun trigger.
  • Aim into a bucket and pull the trigger for a second.
  • Lock gun trigger again, turn the handle back and continue spraying.

General Advice

  • For safety reasons, the tip guard must always be in place when spraying. The pressure of the fluid is very high, and can cause serious bodily harm if it comes in contact with your skin.
  • Always engage the trigger lock when not using the sprayer.
  • Start moving the tip before you pull the trigger and stop holding the trigger before you reach the end of a sweep. This will reduce waste.
  • Spray up and down, not horizontally.