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How to prevent streaks under the window vents when applying a diffuse coating?

diffuse coating is applied more and more often for crops that are not resistant to high ambient temperatures, but do have a need for cultivation light. Using a diffuse coating during the summer, a greenhouse can easily be equipped with a translucent layer that allows light to enter the greenhouse diffusely. When applying a diffuse coating, it is important to take account of points of attention during application. This to prevent that streaks appear under the window vents and to ultimately get an even result. In this article our specialist provides 5 tips.
Prevent streaks window vents diffuse coating
Roger de Jagher
Specialist Shading and Coating | May 20, 2022 | 4 min. reading time 

Ensure that the greenhouse roof is clean

It is important that you always apply a diffuse coating on a clean greenhouse roof. If you don’t do that, the coating many not stick adequately (in some spots). Also, the dirt may hold back the light, preventing you from taking full advantage of the available sunlight

Choose the right time

At nights the dewpoint is lower, due to which the humidity is higher. As mentioned before, a diffuse coating will not dry in case of high humidity. That is why the application of a diffuse coating must always be completed at least six hours before dusk, allowing the coating sufficient time to dry. Also, as a result of dew, the coating could get damaged.

Take account of the weather conditions

Always apply a diffuse coating under dry circumstances. During application of the coating, the exterior temperature must be at least 10°C, while humidity should be no higher than 80%. 

When the weather forecast is doubtful, it would be wise to notify contract workers/employees about this and postpone the application of the diffuse coating until further notice to prevent problems. You should assess, in consultation with the contract workers/employees, whether applying the diffuse coating would be the right choice at that moment. After all, you are the commissioner.

Prevent condensation

As the window vents must remain closed during the application of the diffuse coating, the temperature and humidity in the greenhouse could rise rapidly. After completion of the work, you want to open the window vents as soon as possible, to let the heat in the greenhouse out. However, during the application of the diffuse coating, the temperature difference between the (hot) greenhouse and (colder) outdoor air could create condensation on the window vents. When the windows are opened, these condensation droplets could leave a trace (vertical stripes) on the outside under the window vent. This is nothing serious, but there are different ways to prevent it:
  • Before a contract worker starts applying the diffuse coating, you could open the window vents entirely in order to lower the temperature in the greenhouse in advance. 
  • During the work activities, you could, if possible, close the window vents per climate section, to allow air circulation and cooling through the windows that are still open. You could additionally make use of any fans to transport the cool air from the opened section into the closed sections. This way you keep better control of the climate (which is pleasant for the crop as well as the staff)
  • When a venting section has been coated, it is best to keep it closed for about 30 minutes, allowing the top layer of the coating to dry and make it less vulnerable to the condensation droplets.
  • You can also choose to open the window vents somewhat more slowly after the contract worker has finished his tasks, in order to allow the top layer of the coating to dry and make it less vulnerable to the condensation droplets. 

Delay roof irrigation

If the greenhouse has a roof irrigation installation, it is recommended to make use of it, the day after application of the coating. Then you will be sure that the coating is dry and no damage can be done. 

Take into account that in case of prolonged use of tap water/calcareous water, a thin layer of lime will be created on the coating. This may lead to problems if the coating must be removed. In that case, the limestone should first be removed by use of an acidic agent (e.g. citric acid) before you can use the cleaning agent Removit
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Can't find your answer? Fill out the contact form and our specialist Roger de Jagher will get back to you. On weekdays, even within 24 hours.

How to prevent streaks under the window vents when applying a diffuse coating?

diffuse coating is applied more and more often for crops that are not resistant to high ambient temperatures, but do have a need for cultivation light. Using a diffuse coating during the summer, a greenhouse can easily be equipped with a translucent layer that allows light to enter the greenhouse diffusely. When applying a diffuse coating, it is important to take account of points of attention during application. This to prevent that streaks appear under the window vents and to ultimately get an even result. In this article our specialist provides 5 tips.
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Roger de Jagher
Roger de Jagher
Specialist Shading and Coating | May 20, 2022 | 4 min. reading time 
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Prevent streaks window vents diffuse coating

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Ensure that the greenhouse roof is clean

It is important that you always apply a diffuse coating on a clean greenhouse roof. If you don’t do that, the coating many not stick adequately (in some spots). Also, the dirt may hold back the light, preventing you from taking full advantage of the available sunlight

Choose the right time

At nights the dewpoint is lower, due to which the humidity is higher. As mentioned before, a diffuse coating will not dry in case of high humidity. That is why the application of a diffuse coating must always be completed at least six hours before dusk, allowing the coating sufficient time to dry. Also, as a result of dew, the coating could get damaged.

Take account of the weather conditions

Always apply a diffuse coating under dry circumstances. During application of the coating, the exterior temperature must be at least 10°C, while humidity should be no higher than 80%. 

When the weather forecast is doubtful, it would be wise to notify contract workers/employees about this and postpone the application of the diffuse coating until further notice to prevent problems. You should assess, in consultation with the contract workers/employees, whether applying the diffuse coating would be the right choice at that moment. After all, you are the commissioner.

Prevent condensation

As the window vents must remain closed during the application of the diffuse coating, the temperature and humidity in the greenhouse could rise rapidly. After completion of the work, you want to open the window vents as soon as possible, to let the heat in the greenhouse out. However, during the application of the diffuse coating, the temperature difference between the (hot) greenhouse and (colder) outdoor air could create condensation on the window vents. When the windows are opened, these condensation droplets could leave a trace (vertical stripes) on the outside under the window vent. This is nothing serious, but there are different ways to prevent it:
  • Before a contract worker starts applying the diffuse coating, you could open the window vents entirely in order to lower the temperature in the greenhouse in advance. 
  • During the work activities, you could, if possible, close the window vents per climate section, to allow air circulation and cooling through the windows that are still open. You could additionally make use of any fans to transport the cool air from the opened section into the closed sections. This way you keep better control of the climate (which is pleasant for the crop as well as the staff)
  • When a venting section has been coated, it is best to keep it closed for about 30 minutes, allowing the top layer of the coating to dry and make it less vulnerable to the condensation droplets.
  • You can also choose to open the window vents somewhat more slowly after the contract worker has finished his tasks, in order to allow the top layer of the coating to dry and make it less vulnerable to the condensation droplets. 

Delay roof irrigation

If the greenhouse has a roof irrigation installation, it is recommended to make use of it, the day after application of the coating. Then you will be sure that the coating is dry and no damage can be done. 

Take into account that in case of prolonged use of tap water/calcareous water, a thin layer of lime will be created on the coating. This may lead to problems if the coating must be removed. In that case, the limestone should first be removed by use of an acidic agent (e.g. citric acid) before you can use the cleaning agent Removit
Contact form
Can't find your answer? Fill out the contact form and our specialist Roger de Jagher will get back to you. On weekdays, even within 24 hours.
Roger de Jagher
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