A question of Glass?

[fredrosse]

A note about plastic materials, well documented in the motorcycle face shield arena:

When cleaning any of the plastic window materials, always use cold water. Warm water may remove dirt better, but it invites scratching of these materials which soften considerably when warm. One of the best ways to clean a motorcycle helmet face shield is with a piece of ice, at that temperature the plastic material resist scratching very well, warm cleaning water will result in scratches usually. Lots of insects striking the face shield at 80MPH on a motorcycle, much less of a problem on the water at 6 knots.

[Lopez Mike]

I'll have to try that ice thing. When I was racing motorcycles for a Japanese factory team in the 70's, I just threw away the face shield after every race. And when racing on dirt, I had layers of thin plastic that I tore off every few laps when the dirt began to bother me.

On a boat, the only thing to damage the plastic surface is the person attempting to clean it!

[steamdon-jr]

I am a union glazier by trade and have worked with glass, poly and lexan for almost 30 years now and I would not personally use lexan or poly due to scratching, just go for a 1/8' over 1/8' lami. nobody will ever go thru it, hard to scratch and break. but that is just my personal opinion.

[Lopez Mike]

That's how much I know. I didn't know you could still get laminated glass.

Yes. Very much a good choice.

[steamdon-jr]

actually glass standards are changing, you will see laminated alot more in the future, if you go to a mall and the handrail on the second floor is 1/2" tempered it may soon be 1/4" over 1/4" lami because if it breaks the weight of the glass coming down onto people below could be deadly not to mention a person on the second floor could now fall thru, hence the reason of going to lami in the codes of some cities

[fredrosse]

As to the options, Laminated or Tempered glass, this has to be made up from a supplier to final dimensions, Yes? Who does this in our Phila area, what does it cost (say a 12 x 24 piece of glass), and how long for turnaround from order to pickup?

I know the order time can be a problem, whereas the plastics can be bought at Home Depot and cut in an hour's time for a few dollars. I just had a piece of 48 inch x 36 inch x 1/2 inch thick tempered glass bought for $300 US, for the house shower.

[Lopez Mike]

I have the various retain glass repair companies in my area to be rather quickly responsive and not that expensive. They are often dealing with broken windows that need closing up right away.

Your search engine is your friend.

[Bob Cleek]

The glass pretty much lasts forever. You can calculate the weight of either from the densities. 2.6 gm/cc for most common glass and 1.2 gm/cc for acrylic and polycarbonate.

I have a repair kit for acrylic that claims that you can repair anything from a bullet crater to slight fogging. Depends on how much work you want to do. If it is the usual general accumulation of tiny scratches I just use plea polish. No big deal. If it has gone totally to hell, I just replace it. It's fairly cheap.

[Bob Cleek]

The glass pretty much lasts forever. You can calculate the weight of either from the densities. 2.6 gm/cc for most common glass and 1.2 gm/cc for acrylic and polycarbonate.

I have a repair kit for acrylic that claims that you can repair anything from a bullet crater to slight fogging. Depends on how much work you want to do. If it is the usual general accumulation of tiny scratches I just use plea polish. No big deal. If it has gone totally to hell, I just replace it. It's fairly cheap.

Sorry, Mike... I have no idea how that thing above reposted.

Anyway, another vote here for laminated auto glass. I've "been there, done that, and got the tee shirt" many times over working on boats. Plastics are, in my experience, at least, far more expensive than glass, and they don't hold up worth a damn in the sunlight. The UV degrades them. Then there are the scratches. Replacement is a chore and you do have to pay the big bucks for the good stuff (Lexan, Lexguard, etc.)

The solution is simple. Make up cardboard patterns for your windows, allowing a quarter inch free space all around if you are setting them in wood. This is because wood swells when wet and if you make it a too tight fit, the pane will crack. Bring the patterns to your local automotive glass shop, you know, where you buy windshields, etc. They should be able to cut you whatever size and shape you want and they'll finish the edges for you too. Bring them back and set them in a rebate, filling all around with silicone tub caulk (which remains very flexible... if you use putty that hardens over time, again, when the frame swells, your window will crack.) Be sure to cover the caulk with a trim piece so the sun doesn't get to it, as it will break down in the sunlight otherwise. Be sure not to get the silicone caulk on areas you want to paint or varnish, as nothing sticks to the stuff. (Mask around before setting the window. Clean cured excess silicone off the glass with a single edged razor blade.)

This will last as long as the boat or until somebody drives a truck through it. And it shouldn't cost you an arm and a leg, either. This is how the pros do it.

[Dhutch]

This topics run a bit, but I would use glass rather than acrylic or polycarbonate. Both have there uses, and come in a range of specification, thicknesses, etc. but ultimately will cost and weigh as much as glass, but will never keep scratches away.

Normal 'house' or soda glass is as you say, right out out safety grounds for large panes on a boat.

Laminated glass has a layer of tough plastic down the middle, and a thin sheet of glass both sides, giving you the best of both worlds. It really is bloody strong, and although it will break if pushed, it holders together in a perfectly stable/waterproof etc way with just a few cracks in the outer layer. This is what car windscreens and security glass are made from. Minimum thickness is slightly more than other options for obvious reasons, but assuming you can bear the weight its what I would use. It can also be cut 'while you wait' as you just score, snap, and used a knife on the middle layer.

Toughened/tempered glass is heated and cooled after cutting such that the surface is in tension, which increased the strength and also mean if broken if falls away into small pebbles which are much safer the large sheets/shards as while you can cut yourself on them its much more like mild gravel-rash than potentially deep flesh wounds. This is commonly used on the glass in doors, low level windows, phoneboxes, and boat windows and all the windows on a car other than the front windscreen. You cant cut it while you wait however, and you will find small peddles of glass behind things for the next 18months! So for instance when we broke a window in our wheelhouse (hit a bridge ) it was replaced with laminate for speed.

Good luck with the build!

Daniel