The paint on heating pipes in greenhouses is constantly exposed to humidity, residues and mechanical loads. As a result of this wear and tear, the pipes become less reflective and heat transfer suffers. The best time to maintain your pipes is in the period between crops. An advantage of a water-based pipe coating like PipePaint is that it doesn’t give off harmful vapors that could damage the crop. But there are other advantages as well.

The most important function of paint is to protect the metal from rusting. The second function is to reflect light, and with white paint you can increase light reflection by as much as 20-50%, some estimates say. The third function is to improve heat transfer, which a paint film can increase by about 10%. In theory, this allows you to reduce the pipe temperature as the crop temperature is reached more quickly. But how often do the pipes need to be maintained? That differs depending on the crop and the grower. The more the pipe is affected by humidity, residues or wear and tear from pipe rail trolleys, mobile benches or monorail trolleys, the more quickly the paint will wear. Rust formation should be avoided at all costs.

Preventing crop damage
If you decide to maintain your heating pipes this year, Mardenkro recommends using its water-based PipePaint. This product has various advantages over a solvent-based paint. Firstly, it doesn’t give off harmful vapors. Solvent-based paint can sometimes cause leaf scorch, particularly in young, delicate crops. If you grow pot plants or cut flowers all year round, a water-based paint is recommended in order to avoid crop damage. If you grow vegetables, a water-based paint can be applied in the quiet weeks before crop changeover. This not only saves precious time but energy as well. To dry solvent-based paints, the heating pipes have to be heated up to around 80°C for 24 hours with the windows wide open. That costs time and money. But there’s no need for that with PipePaint: a hand-hot pipe (30-35°C) during application and afterwards is all you need to allow the moisture to evaporate within a day.

No primer needed
PipePaint is a combination of primer and top coat in one. So there’s no need to apply a primer coat first. The quickest way to apply the paint is with a paint mitt, although a pipe roller can also be used. One coat of paint is sufficient for maintenance purposes. When installing new pipes, two coats are recommended to improve coverage and light reflection. Before applying the paint, make sure the pipes are free of grease, dirt and rust. On existing pipes this can be done using a glove and a piece of bent chicken wire. A brand new pipe should be degreased with a soap solution or a degreaser before painting. PipePaint is available from Mardenkro in 15 liter buckets. One bucket is sufficient for about 1,100 m of 51 mm pipe.

For more information
Mardenkro The Netherlands
Geerstraat 8
5111 PS Baarle-Nassau
The Netherlands
T: +31 (0)13 507 70 69