To remove every ReduSystems coating, 250 litres of ReduClean is needed per hectare which is mixed with around 1000-1750 litres of clean water depending on the method of spraying. It doesn’t make any difference whether a thin or thick layer is present on the roof. It is often thought that when the coating is thin or has been weathered that less ReduClean is required. However, this is not the case. The remains of glue that are present on the roof also need to be removed and for that you always need 250 litres ReduClean per hectare. In order to ensure a proper removal you always need to stick to the recommended mixing ratios as indicated on the packaging.
In addition, it is also important that the roof which is to be sprayed is completely dry and that rain is expected within a few days in order to rinse it clean. If roof sprinklers were used while the coating was present it’s possible that the coating will be covered in a layer of iron or chalk. This will need to be removed first by using an acid (for example, oxalic acid) because otherwise ReduClean will not be able to penetrate the coating.
Practical experiencePrecision, both during application as well as during the removal of the coating, is essential. Otherwise you never achieve the required amount of light distribution and, at the end of the season, clean windows again. Wim Vreugdenhil, manager of Marel Loonwerk in the Netherlands, explains how he goes about cleaning a glasshouse. “Every step in the process has to be right. This starts by making the correct dosage: 1200 litres of spraying fluid with 250 litres ReduClean per hectare when applying mechanically and just under 2000 litres when applying manually. Then it’s the trick to distribute it perfectly with the machine or with the spray gun. You choose a machine with the right sprayboom set-up, depending on the width of the bays,” he says. “Then I calculate the correct travelling speed and sprayer pressure which we then set on the machine. You do need to get this right. It’s not guesswork.” His colleagues keep an eye on the machine and check everything is running properly, for example, that all the sprayers are spraying evenly. They can also check digitally if the correct speed is being maintained.
In order to reach all areas the spray pattern of the spray caps has to be set to ensure a certain amount of overlap. “You make a calculation so that everywhere gets an even amount of fluid,” says Vreugdenhil.
Rain shower necessaryReduClean reacts with a binding agent in the coating so that it becomes water soluble. A rain shower then has to rinse the coating from the roof. Therefore the weather plays an important role in both the application as well as the removal of the coating. The roof has to be completely dry otherwise the dosage is no longer correct and you have an uneven film over the roof or insufficient removal at the end.
Vreugdenhil takes all of this into account, within the possibilities that the company has within its planning. “ReduSol can be removed quite easily. Then you can be a little more flexible. But you can always have bad luck such as just a light rain shower so that the coating is not completely washed away. Then you have to do it again. ReduFuse IR is more difficult. Then you really do need a heavy shower within a few days to remove it properly,” he says.
Window vents shutAs well as the rain the combination of temperature and humidity plays a role too. Coating can be applied with the windows a few per cent open but they need to be shut for cleaning. That means that for few hours the grower doesn’t have the climate completely under control because the windows can’t be opened. “If it is really too warm for the grower then we can wait,” he says. “Then we take a coffee break!”
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