What the heck happened to my Lexan windows? And can it be fixed?

[rbthorson]

Could it be the the product used to bed the windows? It looks lie it originated at the top edge of the panes and ran down.

[wind rose ll]

NEVER use an oily rag on Lexan it may be tough but petrochemicals will absolutely ruin it..can not be polished or buffed..needs to be replaced.

[NNBill]

Originally Posted by a64pilot

Lexan is very tough, hard to break. That’s because it’s so soft. It’s also very easily scratche. I’d be surprised if you could polish it out, I would try extremely fine plastic polish, anything courser will likely scratch it badly.
d.
Good luck.

I wonder if a headlight polishing kit would work for that.

[Ric Sheridan]

Aloha,

I have some experience with plastics Plexiglas, lexan and polycarbonate. The fine crazing is caused by alcohol. If you take a rubbing alcohol to a small portion of your glass you can see how it reacts to the alcohol. I have seen big chunks fall off of the other side of 1/2" plastic before just by being wiped down with alcohol. This should be a warning to all who are replacing their windows/ portholes. Polycarbonate is the only way to go. It is the plastic they use on Vending machine covers. Plexiglas and Lexan are not to be trusted.
With your window it looks like either somebody spilled alcohol on your boat or a bird had fermented seeds inside it and did a number on your boat. IMHO. I could be completely off base but I thought I would throw it out there.

[er9]

Originally Posted by Ric Sheridan

Aloha,

I have some experience with plastics Plexiglas, lexan and polycarbonate. The fine crazing is caused by alcohol. If you take a rubbing alcohol to a small portion of your glass you can see how it reacts to the alcohol. I have seen big chunks fall off of the other side of 1/2" plastic before just by being wiped down with alcohol. This should be a warning to all who are replacing their windows/ portholes. Polycarbonate is the only way to go. It is the plastic they use on Vending machine covers. Plexiglas and Lexan are not to be trusted.
With your window it looks like either somebody spilled alcohol on your boat or a bird had fermented seeds inside it and did a number on your boat. IMHO. I could be completely off base but I thought I would throw it out there.

Lexan is a brand name for polycarbonate. Alcohol will not damage acrylic or polycarboanate if its new and in good condition. its a generally safe solvent to use to clean either when cleaning off residue from tape, bedding compounds etc. The fine crazing can be caused by many, many things. Plexiglass (acrylic PMMA) is a fantastic option for windows and generally superior to polycarbonate in many ways. I'm an arcylic fabricator by trade and have been for 26 years. i replaced all my ports with acrylic. good quality cell cast acrylic cant be beat except maybe with glass in very specific situations.

that being said the damage you witnessed was either due to very deteriorated acrylic or acrylic of very poor quality, probably both. alcohol can severely damage poor quality acrylic which i suspect some boat builders and window installers use due to its low cost or ignorance, however...so can paints and solvents of many varieties. once acrylic get close to 10yrs age all bets are off.

[Westcliffe01]

Sorry, I should have elaborated on the video.


This is an example of a polycarbonate headlight cover that had previously been restored by polishing but had subsequently become cloudy due to not having UV protection.


So it is re-polished until it is perfectly clear, then coated with several coats of a UV resistant clear coat. The clear coat is allowed to dry and harden, then wet sanded to remove any orange peel (very gently) and finally re-polished to a mirror finish. The result should last a long time due to the new UV protective coating.


Apparently automotive headlight lenses are clear coated from the factory but the factory finish is usually attacked by the chemicals used in car washes that frequently contain HF acid (there were lawsuits about the HF acid damaging windshields in car washes and voiding the warranty on the windshields). Once the coating is compromised then clouding over is inevitable....

Originally Posted by Westcliffe01

https://youtu.be/GPihLU9ZC-U

[Chotu]

Um.... Lexan IS polycarbonate

Originally Posted by Ric Sheridan

Aloha,

I have some experience with plastics Plexiglas, lexan and polycarbonate. The fine crazing is caused by alcohol. If you take a rubbing alcohol to a small portion of your glass you can see how it reacts to the alcohol. I have seen big chunks fall off of the other side of 1/2" plastic before just by being wiped down with alcohol. This should be a warning to all who are replacing their windows/ portholes. Polycarbonate is the only way to go. It is the plastic they use on Vending machine covers. Plexiglas and Lexan are not to be trusted.
With your window it looks like either somebody spilled alcohol on your boat or a bird had fermented seeds inside it and did a number on your boat. IMHO. I could be completely off base but I thought I would throw it out there.

[Chotu]

Originally Posted by er9

Lexan is a brand name for polycarbonate. Alcohol will not damage acrylic or polycarboanate if its new and in good condition. its a generally safe solvent to use to clean either when cleaning off residue from tape, bedding compounds etc. The fine crazing can be caused by many, many things. Plexiglass (acrylic PMMA) is a fantastic option for windows and generally superior to polycarbonate in many ways. I'm an arcylic fabricator by trade and have been for 26 years. i replaced all my ports with acrylic. good quality cell cast acrylic cant be beat except maybe with glass in very specific situations.

that being said the damage you witnessed was either due to very deteriorated acrylic or acrylic of very poor quality, probably both. alcohol can severely damage poor quality acrylic which i suspect some boat builders and window installers use due to its low cost or ignorance, however...so can paints and solvents of many varieties. once acrylic get close to 10yrs age all bets are off.

How much did you size up the acrylic to make up for its lower strength in comparison to polycarbonate?

[a64pilot]

I haven’t dropped a winch handle and broken a window.
go to youtube and search using a center punch to break a car window to see what happens to tempered glass.
I wasn’t saying put large glass windows on a Cat, just saying if you use glass, don’t go with tempered glass was all.
Yes laminated glass can go bad around the edges from the adhesive breaking down, you can see that in old cars, but look at how old the cars have to be to see the degradation, it’s most often several decades before you see it, but in antique cars over 50 years old, some have degraded windshields, many don’t. I have I think 15 or so portlights with laminated glass that 33 years old, one window has slight degradation on the edges, but it’s so slight you don’t see it unless your cleaning the window. Maybe by the time it’s 40 years old it might need replacing, but does any plastic window last 40 years on a boat in the tropics?

lemon pledge does indeed help with old aircraft windshields, it helps fill in the tiny scratches that are a part of life of old plastic windows.
Cleaning is how plastic windows are most often damaged, we learned to never initially use a rag, rinse off as much as possible with fresh water, then use your clean bare hand with a little soap to remove as much dirt as possible, if you use a rag it traps the dirt and then grinds it into the plastic.

However on weight in a Cat, 99% of the Cats I see are not as weight conscious as we may think, Think of how huge the generators are on many Cats, if you are carrying around a 14KW Diesel generator, well maybe your not real worried about weight.

[capn ken]

Next time you replace glass for your port lights I would recommend safety glass instead of a vinyl. Easier to maintain and if it does crack it will not scatter there’s a layer in between the two pieces of glass.

[er9]

Originally Posted by Chotu

How much did you size up the acrylic to make up for its lower strength in comparison to polycarbonate?

generally speaking we double it but thats just our general rule of thumb, not lab data. on my boat im using 1/2" for the hatches (which have cross bars) and 3/8 thickness for the side ports. I'm also going to use 1/2" polycarb over the side ports as offshore covers but im lucky, my side ports have a thick metal frame with an internal flange i can mount these polycarb covers to.

[rbthorson]

Sorry about the typo, I meant "It looks like"

[MalteseFalcon]

I used a 2 step buffing system produced by 3M first a compound and a polish/wax both done with a foam pad on a buffing machine occasionally spraying water to keep the plastic from getting too warm. They came out good as new.

[SailFastTri]

Originally Posted by LifePart2

Ok, we have a conclusion.

It looks like this CAN be polished out, though it is quite a bit of work. That tells us that the damage is on the outer surface, not inside it caused by UV tunnelling.

After checking our log book and memory, we recalled that the sequence of events was:

1) March 2019 Got Awlgrip done in Trinidad by Perfect Finishes in Power Boats.
2) May 2019 Had windows replaced in St Martin by Custom Fit Marine
3) June 2019 had to go back to Trinidad to get their shoddy job redone.
4) March 2020 left the boat on a mooring in Grenada
5) Came back to find the damage.

So our conclusion is that Perfect Finishes used some kind of product on the coach roof which destroyed our windows. Their re-done job is also still far from a 'Perfect Finish'. Nedless to say we are very unhappy with their work and seriously regret having the Awlgrip done, which was hugely expensive.

I think we will try to polish out the damage as well as we can. Then maybe cover it with a UV-protecting file.

Maybe that will last a while. Eventually I guess we will replace it with Acrylic or maybe glass.

Thank you all for helping us figure this out.

Amonia cleaners can damage acrylic windows. It can cause crazing and hazing. Perhaps this was the cause.

I haven't read the whole thread, so perhaps this has been suggested; but you might be able to polish it out to an acceptable level.

[Icarus]

It's a replacements job IMO
Doesn't look like bird **** it looks more like a run off from some sort of cleaning product or pollution fall out?
Quality of the windows?
I get all sort of bird **** on the hatches which are 40 years old, sofar they are still not marked.