The Ultimate Guide to Caring for Clear Plastic

Posted by Darrell Nicholson at 12:53PM - Comments: (4)

Practical Sailor tester Drew Frye polishes the clear windows on the dodger of his PDQ 32 catamaran being used in our test of clear vinyl brands, and clear-vinyl cleaners and protectants.

Look at any boat more than five years old, and chances are, the clear dodger windows aren’t so clear anymore. By comparison, the windows on one of our test boats remained crystal clear for 15 years. Is clear vinyl really that vulnerable, or are boat owners doing something wrong to shorten its life? The answer to both questions is, "Yes."

One of the best known manufacturers of clear plastic windows for dodgers and cockpit enclosures is Fort Lauderdale-based Strataglass. The company has perfected a highly scratch-resistant coating for clear plastic, originally intended for the automotive industry. It has since become the product of choice for high-end yachts.

I can’t think of any boat product that is as insistent as Strataglass that customers use specific name-brand products for cleaning and protecting their popular clear-plastic windows. To do otherwise risks voiding the company warranty. Normally, this approach rubs me the wrong way. Insisting that we buy Brand X cleaner to clean Brand Y product limits competition and can add hidden costs for the consumer. But I’m willing to cut a bit of slack to Strataglass. The company has managed—against all odds—to keep its high-volume textile operation here in the United States while many sailmakers and other marine textile plants have fled offshore in search of cheaper labor.

In addition, the Strataglass-endorsed cleaners and protectants, made by Imar, have done well in our previous tests of clear plastic cleaners and protectants, and the prices aren’t significantly more than competing brands. But as usual, we remain skeptical—and curious. What about homemade cleaners, like our anti-mildew concoction that is 35 times cheaper than what you buy at West Marine?

With the hopes of finding a cheaper way to protect our $150-plus Strataglass dodger windows, we are testing other cleaning products and protectants on the company’s two types of clear plastic. Is Strataglass’ insistence that we stick with Imar well-founded? Or is it a mixture of paranoia and propaganda? Based on our initial testing, it appears that the company’s concerns about using the wrong cleaner or polish are well-founded. We were surprised to find that some everyday products—including sunscreen, bug spray, canvas treatments, and mildew cleaners—can do irreparable harm to Strataglass.

Strataglass user’s maintenance guide states the following: “We recommend using only Imar Products, Imar Strataglass Protective Polish, Imar Strataglass Protective Cleaner, and mild soap (preferably Imar Yacht Soap Concentrate) on Strataglass. We no longer recommend the use of any other products, regardless of the manufacturer’s claims. Use of harsh cleaners like Simple Green and/or pine will dull the curtains quickly. Using any other product(s) void the factory warranty.” It goes on to warn against RAINEX, Pledge, or Plexus and says that scratch removers and other products made for “regular, un-coated vinyl will damage Strataglass.”

So there you have it. It’s the Imar way . . . or the highway.

While we consistently advise readers to adhere to manufacturers’ recommendations, we have made a few observations regarding Strataglass of our own:


There are many common boating chemicals that can ruin vinyl windows and are rough on other plastics:

• Sunscreen: Sunscreen handprints on vinyl are difficult or impossible to buff out. Sometimes, the handprints occur when a guest helps roll up the windows, and you may not see them until the next morning, when dew “develops” them, inside the vinyl. Keep a washcloth handy for wiping hands, or better, wash hands before touching the clear vinyl.

• Insect repellent: DEET will melt vinyl. Even a fine spray will haze many plastics. We recommend politely asking guests to use insect sprays well outside of the cockpit area, away from all windows, and to wipe or wash their hands thoroughly when finished. Consider banning aerosol bug repellents from your boat.

• Vinegar: If rinsing your vinyl windows with fresh water and polishing them with a spray polish does not remove all of their spots, the spots are very likely calcium deposits. Use a 10-percent solution of vinegar and water to clean them, rinse thoroughly after use, and apply a protectant.

• Canvas water repellents: As we reported in the December 2013 issue, some canvas waterproofing treatments are quite tough on vinyl and can ruin it within minutes. If you treat your canvas, be certain to apply a fresh protectant coat to the windows before you begin, cover the windows, and then wipe the vinyl with a cleaner/protectant after you are finished.

• Silicones and solvents: All manufacturers advise against using products on vinyl that contain silicones, petroleum solvents, or alcohols. Small amounts of certain alcohols are permitted in some cleaners but not the use of alcohol-based glass cleaners.


Covering clear-vinyl windows offers fool-proof protection from harmful UV and dirt. The downside—other than cost and the added time before and after sailing—is the risk of abrasive wear between the cover (typically Sunbrella) and the window. We’ve heard of folks using textured Phifertex covers and finding that their windows have a fine checkerboard pattern within six months. We’ve also heard reports of damage in windy harbors from the covers constant flapping; in the wind, the best solution seems to be consistent cleaning and use of protectants.

Some folks use Sunbrella with an integral lining, but dirt can imbed in the lining, resulting in worse abrasion than plain fabric. Wear is very often related to the size of the dirt particles, and lined Sunbrella can hold larger particles than unlined Sunbrella.

For the best of both worlds, we suspended awning covers over the dodger windows. There’s no chance of abrasion even if the window is salt- and dirt-encrusted; UV and bird bombs are blocked; and they can even provide expanded shade and reduce the need to close the windows for a passing shower at anchor.


Use only soft polishing cloths to clean clear vinyl. Clean cotton jersey (T-shirts or polishing cloths) are safe, but paper towels may leave scratches (grit left over from the paper-making process is much harder than vinyl). Microfiber cloth is a favorite as well, but it must be kept very clean as it quickly attracts dirt.

Rinse the windows with water before polishing, and change to a fresh cloth every 5 to 20 square feet, depending on how clean the window was at the start. Turn the cloth frequently.

Storing Windows

Only roll up vinyl windows when they—and your hands—are clean. Salt spray is abrasive and can cause minor scratching. It’s better to squint through salt-encrusted vinyl until a freshwater rinse is practical than to have your view blocked by scratches for years to come. A handy fresh water squirt bottle can help rinse at sea. Alternatively, remove the window panels. If you’re rolling up the windows for storage, roll them with soft, clean fabric to keep the vinyl from touching itself and potentially abrading the surface.

If you plan to roll up your windows regularly, you’ll likely be happier with a thinner vinyl material (30 mil vs. 40 mil) or more flexible products (O’Sea and Regalite, vs. the stiffer Strataglass) since less force is required and less scratching results.

Cold Weather Care

While many folks put their boats away for the season as soon as they need socks, some sail into the fall or even year-around; the further north, the greater the urge to stretch the season. As temperatures plummet, we become more and more accustomed to the chill, and by January, some think 32 degrees is quite comfortable for a day on the water, if dressed for it. However, vinyl does not acclimate, and depending on the gauge—thicker is stiffer and more vulnerable—rolling or flexing old vinyl windows at temperatures below 60 degrees is just asking for trouble. The more worn and hazed the windows become, the greater the urge to clear the view by rolling them out of the way, and suddenly the window has a crack running halfway across. A good rule of thumb is to wait to roll windows until hats and gloves are forgotten (over 60 degrees). If there is dew or frost on the windows, wait for the sun to remove it.

Scratch Removal Products

Our early testing suggests the actual vinyl-restoration process might compromise the material’s protective coatings and lead to premature weathering, even if applied to just a few scratched areas. We’ve added some “restored” windows to our long-term test racks, but it is clearly better to keep windows scratch-free and UV protected than to restore damaged vinyl.

If your vinyl windows have some damage or weathering, and standard cleaning and polishing is not doing the trick, try laying them on a flat, towel-covered surface and polishing very firmly with Imar Protective Polish. This was effective in removing light oxidation and providing deep cleaning as the polishing, without the risk of abrasion or coating degradation.

Comments (4)

I've noticed this year with the excessive heat that a gray or fogging has occurred on my boat cover plastic windows. I clean them often with clear water and a little mild detergent. At the end of the summer season I store them inside. Do you have any suggestions on restoring the windows to a clear view. The plastic windows are 10 years old.

Posted by: Harry orlando | September 24, 2016 10:30 AM    Report this comment

TSP is agressive towards almost any material that is shiny, glossy, amd smooth

Posted by: Unknown | January 5, 2014 10:45 PM    Report this comment

The washing soda and borax based anti-mildew formulas were intended for cabin use. These DIY formulas are water-soluble, so although they might work on the underside of a canvas dodger, they will likely rinse away from the top in the first rainstorm. Nevertheless, we have since tested these, as well as 3M and Goldshield anti-mildew formulas on Strataglass and Regalite. Applied in the normal manner and allowed to dry, ALL of these will cloud vinyl windows. However, if exposure is limited and they are rinsed off before drying, no damage should occur. We have seen this same type of clouding damage caused by every highly alkaline cleaner; windows should be cleaned and polished only using products specifically formulated for vinyl windows, and at this time our recommendation is to stay with Imar products.

Posted by: sailordn | December 13, 2013 10:14 AM    Report this comment

Would the mildew cleaner (TSP, baking soda and sodium carbonate) solution harm the strataglas, if some were to drip from the canvas onto the window?

Posted by: George C | December 11, 2013 10:18 AM    Report this comment

New to Practical Sailor?
Register for Free!

Already Registered?
Log In