An improper or eroding greenhouse frame is often the unsuspecting culprit in the premature decline of a greenhouse cover. There are a variety of issues that can result from the type of greenhouse frame you use. Wood frames, for example, can be damaging to plastic sheeting, while also harboring unwanted pests. Metal and aluminum frames absorb heat from the sun and can literally melt the plastic sheeting at the touch points.
Additionally, PVC or polyvinyl chloride, is efficient, lightweight, flexible, and inexpensive, so it's also a popular choice for greenhouses. However, when polyethylene with hydrocarbon derivatives come into contact with PVC, the PVC acts like a solvent. Over time, when exposed to high temperatures and UV radiation, the PVC can chemically react and release hydrogen chloride acid, which damages the polyethylene or greenhouse cover touching the PVC.
Painting the PVC white with an acrylic-based paint or applying white felt tape to the greenhouse structure can reduce damage by preventing the migration of chemicals from PVC piping to the greenhouse cover. Using white felt tape is a great solution, and will also:
Prevent greenhouse cover damage during installation.
Prevent metal or galvanized steel from overheating and melting the greenhouse cover.
Reduce friction against rough edges and splinters.
Allow for easy movement of poly.
Protect your investment.