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Old 02-03-2016, 09:58   #16
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Re: Which sealant for Lexan

To protect the Lexan in my Lewmar hatches, I had Sunbrella covers made.

Using butyl rubber to bed the Lexan storm shutters over my existing ports will allow me to replace the Lexan when it is crazing...if I live so long.
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Old 02-03-2016, 10:20   #17
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Re: Which sealant for Lexan

I like Lexon because it is bullet proof. But if scratches. You may do better with safety glass?
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Old 02-03-2016, 10:27   #18
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Re: Which sealant for Lexan

Thanks so much, everyone. I'll research your replys.
Ken
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Old 02-03-2016, 10:27   #19
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Re: Which sealant for Lexan

Quote:
Originally Posted by Scaramanga F25 View Post
Have you tried an industrial automotive glass supplier/cutter as in buses?

I have had them cut a flat windshields, with radiused corners, for dune
buggies.

This, we have the windshields for our aircraft cut at the local glass place, it's the laminated safety glass, like what is in a cars windshield, it may be a whole lot cheaper than you think and glass last a long time.

Lexan is extremely tough, really is almost bullet proof, it is this way because it's soft, it gives as opposed to breaking, being soft it scratches easily and is not very UV resistant.
From a first look, it would appear to be a very good aircraft windshield, hit a bird and the bird bounces off, not break through, but because it scratches so easily and is damaged by UV, it's not.

Price the glass before you go down the Lexan route. If you want plastic, Plexi may be a better choice.
Plexiglass and Lexan are both brand names I believe, but I don't know the correct name
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Old 02-03-2016, 10:33   #20
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Re: Which sealant for Lexan

There are many caulks/silicones that will stick to lexan but not many that will act as an adhesive. Sikaflex 295 UV is one of the few that will adhere. This is important only if you need adhesive qualities as well as a sealant.

Sikaflex 295 UV

As previously mentioned, although lexan (which is polycarbonate) is supple and strong, it is not UV resistant and will glaze over permanently after a fairly short period if exposed to sunlight. It is also not as scratch resistant as acrylic. Acrylic is therefore preferable for hatches IMHO.
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Old 02-03-2016, 10:33   #21
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Re: Which sealant for Lexan

Use a high strength GE silicone adhesive (scs1200). It is clear, will last the life of the Lexan and no leaks!
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Old 02-03-2016, 10:36   #22
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Re: Which sealant for Lexan

I would strongly recommend taking these peoples advice: Which Sealants To Use – Selectplastics
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Old 02-03-2016, 10:39   #23
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Re: Which sealant for Lexan

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Originally Posted by George DuBose View Post
Just to give a different opinion, Sikaflex makes a system of sealants and primers that will give a secure bond between Lexan and aluminum. It's a bit complicated, but gives great results.

I cracked one of the pieces of new glass when I was replacing the old glass that was in my ports and it was the devil to remove the frame and the broken glass.

I am going to screw pieces of Lexan over all my ports as permanent storm shutters and for this I will use butyl rubber.
The question is : Does the OP need a "glue" type sealant to hold the lexan/glass in place without any other fasteners or frame?
Or does he have a frame with inside & outside flanges that will hold the Lexan/glass from falling out & he only needs a bedding compound to waterseal it?

For holding AND sealing-use Sika,4200,or your favourite compound-except silicone.
Silicone is only useful as a gasket between two mechanically clamped(by bolts/screws,etc) items & has very few if any uses on a boat.

For waterproof bedding of mechanically held components(deck fittings,windows,etc.) that you may want to remove in future,it is hard to beat butyl.

Note: If you are holding Lexan or similar plexiglas products by screws,make sure you drill the holes in the Lexan twice as large as the screw diameter & don't tighten them past the point of just starting to squeeze the sealant. Lexan & similar plastics expand/contract greatly & will crack/break at the screws if it cannot move.

just my experience

Cheers/ Len
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Old 02-03-2016, 12:13   #24
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Re: Which sealant for Lexan

Use primer on Aluminium
As a trademark,Lexan = Perspex = Plexiglass

Glass can be dangerous, and does not bend, that which in some cases is a necessity
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Old 02-03-2016, 14:23   #25
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Re: Which sealant for Lexan

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I used Dupont 795 on out Hatch lexon replacement and worked excellent. UV will degrade and cause crazing in lexon in fairly short time, so glass would be recomended though much more expensive.
I bought a good old boat and the previous owner had replaced all the glass with lexan. I didn't know this and attempted to clean some adhesive off one porthole with acetone. Bad mistake as you can't see clearly through the porthole anymore. Of course before it dawned on me that it was lexan I kept rubbing on the damn porthole thinking the adhesive was just smearing and not coming off.

I have since decided to replace all my portholes with safety glass. Sure it'll be more expensive than lexan but I feel there will be fewer problems.
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Old 02-03-2016, 14:34   #26
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Re: Which sealant for Lexan

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Originally Posted by TheThunderbird View Post
Use primer on Aluminium
As a trademark,Lexan = Perspex = Plexiglass

Glass can be dangerous, and does not bend, that which in some cases is a necessity
That is BS. Lexan and Plexiglass may both be polycarbonates but vastly different.
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Old 02-03-2016, 14:53   #27
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Re: Which sealant for Lexan

Lexan is polycarbonate. Perspex/ Plexiglas is not. Lexan is bulletproof IF thick enough. I have shot .22 bullets through 1/4 inch lexan with no problem.
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Old 02-03-2016, 15:06   #28
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Re: Which sealant for Lexan

I offer my excuses to all but one.

"
Plexiglas Acrylic Vs. Lexan .
Plexiglas, a trade name for acrylic, and Lexan, a trade name for polycarbonate, perform in much the same way: their clear, glass-like properties make them ideal for industrial and consumer products such as race-car windshields, aquariums and various kinds of lenses and computer hardware. Both materials are used in safety equipment because of their strength and resistance to shattering. Each have slightly different pros and cons, though, depending on what you're using them for."
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Old 02-03-2016, 15:06   #29
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Re: Which sealant for Lexan

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Originally Posted by Steve Bean View Post
Lexan is polycarbonate. Perspex/ Plexiglas is not. Lexan is bulletproof IF thick enough. I have shot .22 bullets through 1/4 inch lexan with no problem.

Just for shits and giggles. I shot a 1/4 inch piece of Lexan with a 38 spec..

At about 25 ft. Fractured it and just glad my dumb ass didn't get hit by the rebound.
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Old 02-03-2016, 15:32   #30
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Re: Which sealant for Lexan

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Originally Posted by TheThunderbird View Post
Use primer on Aluminium
As a trademark,Lexan = Perspex = Plexiglass
Lexan is a trademark for polycarbonate.

Plexiglas is a trademark for acrylic.

They are very different in both properties and longevity. While both the Coast Guard and the Forces use Lexan it is replaced every 3 years.

Plexiglas will outlast Lexan by many, many years.
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