Paint Consumption – Coverage and Spreading Rate Guide

Aug 7, 2023 | News

When painting a surface, the amount of paint used for certain areas depends on the following factors.

  • Required thickness.
  • Volumes solids of the paint.
  • Surface roughness.
  • Application conditions (wind, temperature, etc.).
  • Application technique.
  • General wastage (material left in the drum, over application, etc.).

For this blog we will primarily focus on required film thickness – a vital part of a coatings durability performance and application methods. When coatings are used, they are either applied by hand brushing /rolling or spray application. To make sure you get the most out of your coatings, it is vital to get the right amount of paint on the surface.

Sometimes determining the correct amount of paint can be a challenge and potentially costly if incorrectly budgeted for. In addition to purchasing the correct amount of paint, each application method also has pros and cons.

So, what is the difference between hand brushing /rolling and spray application?

Brush / Rolling

  • Less prep work i.e., less masking on the surface required.
  • More attention to paint detail require, can be difficult to paint around tricky surfaces and obstructions.
  • Thicker paint strokes.
  • Uses less paint per square metre.
  • Can be physically demanding and time consuming.
  • No costly machinery or paint protection accessories required to complete the job.

Spray – Conventional (Air) Spray & Airless Spray

  • High quality surface finish.
  • More preparation work required (masking and taping required for all surfaces you do not want painted).
  • Easier to spray tricky surfaces and obstructions.
  • Faster than painting once you start.
  • Optimal spray distance 10-20cm.
  • Will use more paint during spray application and clean up.
  • Potential risk of a thinner application if note done properly.
  • Can be difficult to master even spray application (cross – coat may be required vertical than horizontal spray).
  • May need to dilute the paint.
  • Will need a spray machine – added cost.
  • Coveralls, respirators, and goggles.

Spraying a surface as opposed to painting a surface will use on average three times more than brushing. It is also important to mention that when spraying a coating, paint will disperse (over spray) during the process. Once the job is completed for the day any paint left in the spray machine must be blown out. This will also result in some wastage of paint.

Loss Factor Considerations

There are two types of loss factors to consider. Losses encountered vs. theoretical values for spreading rate. This includes material left in the drum and hoses of spray equipment to material spillage or missing the substrate due to complicated designs and small dimension parts. Each application technique has its own expected loss factor – expressed as a percentage of paint consumed*.

Brush or RollerTypically, between 10-15%
Conventional (Air) Spray50% is no exception
Airless SprayUsually, 30%

*Loss factors are estimations only. These percentages are based on local conditions, painters experience and other factors.

So how do you know what application will work for you?

There is no right application method, both methods have pros and cons, and it will come down to personal choice, cost, and time. Always be sure to measure the surface area you are intending to coat, and factor this into the amount of coating you will require, and application method chosen.

All surface areas must be adequately prepared and cleaned prior to starting. Follow all paint manufacturer’s instructions on the label, technical datasheets and SDS’s. If in doubt, contact the paint manufacturer’s technical department prior to starting the job. In areas subjected to prominent levels of direct UV sun exposure, potential rain exposure, high traffic areas, an extra coat may provide more protection.

This article should be used as a guide only. This article is for informational purposes and should not be relied on as application variables affect product performance. The user must satisfy themselves as to the suitability of this product for their requirements. Mirotone assumes no liability for use on thus information.