Question:
What's the right way to maintain the plastic windows in my soft-top?
Answer
The material used for the `plastic' windows in convertible tops, soft-tops, boat enclosures, etc. is a specialized type of vinyl called `Pressed Polished Sheets', or 'pressed poly'. The material is actually two layers of non-colored vinyl laminated together under intense pressure and high heat. This process squeezes out all the impurities and renders it perfectly clear.
This material is soft and easily scratched and is not made in rolls but in sheets, which are separated by paper. Also known as `sheet goods', finished stock is always gently rolled and then stored and shipping standing vertically, never laid down. Pressed poly is known by its gauge - 20 gauge is made from two 10 gauge pieces, 40 gauge from two 20 gauge pieces, etc.
On clear vinyl plasticize loss and UV exposure cause embrittlement, yellowing and failure. Like all vinyl, clear vinyl contains plasticizers (to keep it soft and pliable) and UV stabilizers (to retard UV degradation)
Clear vinyl loses its plasticizers much more rapidly than top-coated vinyl. An UV protection added in the manufacturing process is less effective each day. Consequently, if clear vinyl windows on a vinyl soft-top are not properly cared for, they can fail within 2-3 years while the vinyl top itself will last for years longer.
