UV damage thru glass ?

I store a carbon fiber canoe in a back room near a window. (It’s 303’ed) Due to exposure no direct sunlight falls on hull but wondering if indirect light or UV rays can pass thru glass & damage hull ? Guess safest bet would be to throw an old blanket over hull but is this necessary ?


e glass vs. ordinary glass
Makers of new and replacement windows advocate E glass as offering far more protection from ultraviolet light than the average window (untreated glass).

The data’s been out there for over ten years and has credibility with industry groups like WDMA (Window and Door Manufacturers Association) which is currently revising the North American Fenestration Standard for new and replacement windows. I am not in that business but work in construction so have some general knowledge.

So it seems yes, unless you have e-glass or provide some other UV deflecting coating or cover,

either on the glass or on the object to be protected, that

UV rays will affect whatever you are storing indoors near that window. This includes carpets, upholstered furniture and of course boats :wink:

I wouldn’t miss sleep over it. Your
resin is probably vinylester, not as susceptible to UV as epoxy, and your outer fabric layer is carbon, not UV susceptible at all. Even ordinary window glass does reduce UV, and the sun isn’t shining through that window all day.

Maybe …
… he should just apply 303 to the windows?

Consider plexi
Regular glass is a little less than 50% UV resistant. Regular Plexiglas is roughly 80% UV resistant.

Plywood is 100% UV resistant.

In my own garage, I had two large windows and one smaller one and I was concerned about UV damage to my canoes and cars stored in there long term (after seeing how some things near the windows had faded in a year or so).

I had also installed a LOT of lights in the garage when I built my wood kayak, and the neighbors complained about the way it lit up the side of their house. I work nights, so it is not unusual for me to be doing projects at 3am.

I covered the windows with plywood on the inside. I painted the outer surface the color of the house and the inside surface white.

This was about ten years ago, and I have been really glad I did it as there would have been noticeable UV issues with things by now, plus the added security (even if it is only 1/4" luan plywood it keeps wandering eyes out and is still more secure than just glass.

colored 303 just to be sure nfm

hey now
With knowledge like that you’re going to give some architect fits :wink:

Thanx for feedback
Glass is original to home, 170yrs+/- so likely no “e”'s in it. Pleased to hear carbon & vinylester are UV resistant.

Canoe is stored in home we’ve painstakenly restored over yrs so will skip the plexi & plywood

Thanx again for helpful replies

Cover it or 303 regularly
You’ve got quite an investment. Though it may “not be very susceptible,” 4-6 months of a little susceptibility can add up to substantial damage.


gotta get my patent going on colored 303 before some damn naval architect or kayak designer does.

Sometimes my job involves giving them fits, other times to smile and soothe them into giving us

no cost changes :wink:

No, it can’t. Get realistic.

I’d say little to worry about…
The key is your words, “no direct sunlight”. While I guess a little UV rays might bounce around, unless it’s getting hit by direct sun for part of the day, there won’t be enough UV hitting it to matter much, especially if it has the 303 on it or similar UV resistant coating.

Why not…
…just go ahead and do as you originally mentioned: throw an old blanket over your boat? Seems to me like that would end any possibility of a UV problem.

FWIW, and this is just a general boat-care statement, has little to do with your situation: when I was rebuilding the structure that became our boathouse I eliminated all windows. When I leave the building & close the doors it excludes virtually all sunlight. I store a variety of canoes made out of various hull materials – better safe than sorry when it comes to UV degradation. The lack of windows also excludes wondering eyes… I don’t live in a high crime area, but again, better safe than sorry.

UV damage
Ultraviolet radiation can be measured as microwatts per lumen. Lumens are a measure of overall light levels, like foot-candles or lux. Reduction of full-spectrum light levels should be adressed before trying to filter out the more damaging frequencies like IR and UV. How about a curtain or pull-down shade?

no cost changes?
Ah, do they exist? There’s ALWAYS a cost (don’t get me started…:wink: )

New Kevlar boats stored in my garage
w/no windows show no darkening, boats hanging from shop ceiling (shop has full front windows w/overhang) will darken while hanging. Those boats ARE NOT hit by direct sun rays in any way.

I’m with Stickman
My experience tells me that anything not mineral is gonna suffer from UV exposure. The damage is cumulative and cannot be reversed. Faded items that are stored in the dark will not regenerate. Transparent materials like “skincoat” vinylester resin get a double dose of radiation, once on the way in and again when reflected back out. I’d keep my stuff at 65 degrees Fahrenheit, 50% relative humidity and in the pitch black if I wanted it to last forever. Otherwise, common sense must prevail!

And yours ain’t common sense.


– Last Updated: Nov-08-07 5:39 AM EST –

Follow that advice & you'd better not paddle at all.

Exactly my point, Cockeye and GD2! Most of us don’t paddle museum pieces. Common sense dictates that we must expose ourselves, along with our stuff, to certain risks in order to fully experience and understand our existence, or just have fun! Some want to protect and preserve their stuff while not in use. I was simply trying to illustrate the impracticality of ideal storage conditions. That said, there are steps one can take to mimimize damage while not active, like not smoking (your body), or keeping your boat out of the sun.