PSA: Sunbrella Covering Acrylic Hatches

[jigray3]

I have a large sliding companionway cover that has been partially covered by green Sunbrella for about 10 years. I would have thought the Sunbrella would protect the acrylic from damage, but just the opposite has happened. I have significant crazing in the Sunbrella covered area of the acrylic, and almost none in the uncovered area. I can only conclude that the heat from dark Sunbrella in sunlight caused the acrylic to craze. It is really unfortunate because this slab of cambered acrylic will be very expensive to replace.

My advice is that if you are considering covers for your hatches, think twice about using Sunbrella or any dark fabric that retains heat. Seems acrylic hates the heat more than the UV.

[JPA Cate]

Hi, Jigray,

Your acrylic crazing may be due either to stress in the acrylic, if it was just bent to the camber, rather than "melted" on a form. Another common cause of acrylic crazing is using an ammonia based cleaner on it, like Windex. It does craze also, from UV exposure. Don't know what caused yours, but obviously green sunbrella does not reflect much UV.

Sorry not to be more help.

Ann

[southernupdate]

A shame about your hatch, it sounds expensive.
It is probably not a problem with the sunbrella. Although a dark colour, sunbrella is a fully breathable fabric unless the one used has a rubber-ish or polyurethane backing (Seamark or Sunplus). The darker colours still get hot, but air circulation means there shouldnt be damage to the surface underneath. As a marine trimmer, I recommend a product called 303 Aero Space Cleaner, excellent cleaner for acrylics that puts a protective layer on the surface, and even has a sunscreen. Your local trim shop should stock it.
Hope this is of some help, unfortunately it wont repair existing damage
Kim

[ohdrinkboy]

i've had the same problem on the windshield of my pontoon boat. it stays under cover 99% of the time and i use 303. have no idea what the problem is other than it is 10 yrs old. btw cover is a dark tan.

[southernupdate]

Thats interesting, I wonder why. Ive also been using 303 on my covered acrylic hatches for years, and they are in great shape. Just thinking, is the windscreen curved? And / or under tension? Perhaps it has nothing to do with heat or sun at all

[ohdrinkboy]

mine is curved. i can take a picture over the weekend.

[Cheechako]

Hard to argue with a sliding door that crazed under sunbrella and didnt adjacent....

[jigray3]

Originally Posted by Cheechako

Hard to argue with a sliding door that crazed under sunbrella and didnt adjacent....

Exactly. It is the same large piece of 20 year old 3/4" acrylic, but only the covered part is crazed. The exposed part is clear. I wanted to share this info because the conventional wisdom is that acrylic crazes because of exposure to UV. That does not appear to be the case here at all.

[delmarrey]

I don't like green anyway!

You need to get the right stuff..... http://www.tapplastics.com/product/p...c_sheets_rolls