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Plexiglass window restoration

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    Posted: 21 June 2014 at 4:08pm
Hi all,

The previous owner of my boat epoxied the top deck but in the process there are now several "runs" of epoxy where it dripped down the sides and he didn't notice before it dried.  One of these areas is the plexiglass cabin windows which now have white epoxy drips on them.

I'm wondering how to remove these and/or restore the windows in some way?  I'm assuming the epoxy would have essentially bonded itself to the plexiglass and simply scraping or sanding it off won't do a sufficient job.

So my question is whether anyone has any suggestions for removing the epoxy or replacing the windows altogether in which case suggestions on where to source this materials would be appreciated.



Thanks
Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote George S. Quote  Post ReplyReply Direct Link To This Post Posted: 21 June 2014 at 10:54pm
hi Chris,

Frank/Voila is the guy who will know the compatibilities of the different materials you are dealing with.

I am probably going to replace the windows in WarBird this summer. Not because they are leaking (so one wonders.... why replace them)........... well, rather than use tinted plexi, someone just left the mylar (?) tint on the inside of the windows which now looks ugly. Frank has replaced Voila's and we have a plastics fabricator in our yacht club that has the template for this.......... so if you want a new set let me know and maybe I can get a discount for 2 sets. Bill might chime in here if the L28 window openings are not exactly the same, but I think they were..... Bill ?

It was great meeting you when you were in town, and it wasn't a great surprise that you guys beat us in that wednesday night race, with three L28 owners on board Voila, you would have had a lot of explaining to do if you hadn't .......... :-)

cheers,
George
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2014 at 9:23am
All windows are indeed identical. Except they differ from port to starboard because of the radius on the outside edge. They were originally Plexiglass 1/4" thick. Do not use acrylite it's not the same quality acrylic. I used to use a company in Ottawa called Canus Plastics. 1-800-267-9699 and dealt with Don Pineau. They used to have templates for the L28 but it's been years since I spoke with them. Also plexiglass can be sanded and polished like gelcoat. So any deficiencies can be dealt with in that manner.


Edited by Bill Layton - 22 June 2014 at 9:24am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Winner Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2014 at 10:26am
Hey Bill sounds like it's worth trying to restore and if that doesn't work, I can go the replacement route.

So I'm thinking sand with 220 grit and then progressively up, finishing with a polishing paste?
Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2014 at 10:37am
Correct that's the method. But a buffer with proper compound will help at the end.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote George S. Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2014 at 10:50pm
hi Bill,

Just wondering.... Would Canus also have the template for the front hatch ?

I've emailed them about the windows.

cheers,
George
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2014 at 11:01pm
It's possible but I don't know.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote George S. Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2014 at 2:22pm
Just rec'd email back from Canus. Your contact and the window templates have disappeared it seems. I will source locally.

George
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Winner Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2014 at 2:36pm
Hi George I'm gonna try restoring my windows before proceeding with a replacement.  I'll let you know how it goes.
Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote frfletch Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2014 at 3:43am
Chris,
I would try first cutting the epoxy off with a razor blade and then deal with the aftermath. When you sand, I would start with 320, wet, on a small board and I would mask off about 1/2" each side of the drip to keep your sanding onto the direct drip and avoid scratching up the whole window. 320, 400, 600, 800, 1200 (all wet) then polish.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2019 at 8:16am
Hi All and happy holidays,
With regards to removing the window, any hints, tips, or tricks? I tried counter sinking the epoxy over the hole but the drill bit hit the screw and could not bore deep enough to relieve the epoxy. I guess next I would try a grinder but that will only expose the top... is that sufficient to release the screw? thx, john
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2019 at 8:55am
If you can get the nuts off inside then the window will remove with the bolts. This matters not because installing new windows now are done without the bolts and nuts. We now use Dow Corning 795 to glue the window in place. https://www.dow.com/en-us/pdp.dowsil-795-silicone-building-sealant.01595717z.html  

It's works perfectly without fasteners and eliminates all water leaks. Using fasteners causes cracking around the fastener holes which eventually causes the windows to fail.

So if you have to grind the plexi/epoxy away to get to the fastener head it's of no consequence as the windows likely need to be replaced anyways.



Edited by Bill Layton - 23 December 2019 at 8:56am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2019 at 1:39pm
Thanks Bill, I'm not really sure how to remove the interior window trim to get to the nuts; is there a trick to that? john
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2019 at 1:46pm
They are just snap on plastic moldings - 4 pieces per window. Just pull each piece off. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 27 December 2019 at 5:35pm
I made a mold for the starboard window and I'm going to send it to ePlastics and have them make a new window. If you need a window it would be easy to run another at the same time. Let me know by 2020-1-1. john
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 28 January 2020 at 7:56pm
ePlastics James said that the plexiglass does not need to be molded so I just need to glue a flat piece.
Bill, do you use gray glue?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 28 January 2020 at 9:55pm
Correct the plexiglass window bends easily to fit the curve in the deck.

These are instructions for installing new windows without fasteners on the L28. The boat flexes and the original window fasteners cause the windows to crack and leak after very little use. I replaced my windows 3 times over the years using the original fasteners and they leaked like crazy every time no matter what sealant was used. Special sealant now bonds the window to the gelcoat and it works perfectly without any fasteners. But if you use fasteners the windows will crack and leak... so fasteners are a no no. Learned this one the hard way. There are a few tricks below that describe how to do it properly. 

Buy a new set of Acrylic windows (plexiglass not Lexan) that are 3/8" bigger than the perimeter of the original windows all the way around. This gives you added gluing surface that will be necessary in the absence of fasteners.

You need to clean the gelcoat fiberglass surface very well by scraping all the old sealant off and using Lacquer thinner on a rag and on a scotchbrite pad to be sure you have a super clean surface on the gelcoat. This is very important to have it perfectly clean without any remnants of old sealant left behind because we are only using sealant to bond the new windows to the gelcoat.

Make some small wood blocks. It's simple and they are used to align the new window to sit in to the correct position.  Make 3 per side and put some of the tape (3/16" thick foam tape with glue on each side) on one side. Then I used the old window and put it in place with 2 fasteners (one at each end) then I used another small piece of wood that is 3/8" wide(because new windows are bigger by 3/8" all way around) and rested the small piece of 3/8" wide wood against the bottom edge of the old window and on the ends in all 3 places and then stuck those 3 pieces of wood in place on the gelcoat. Now you remove the old window and put the new one in place and you'll see the cut out in the deck for the window is perfectly centered in the new window.

Using the same foam tape cover the faster holes in the deck all the way around. We stick it on so that it just covers the fastener holes and then we trimmed it flush with the edge of the fiberglass hole with an xacto blade. Now all you do is peel off the film on the outside of the stuck on tape and lay the new window in place against the wood blocks and push it in place firmly so that the window sticks to the tape well. Then you can remove the wood blocks and start with the caulking Dow Corning 795.

The trick now is to get the sealant to fill the gap that is left in the oversized window. So just using a caulking gun doesn't get the sealant all the way in against the tape. We had to use a couple of 3" putty knifes (two of us working at it) to pack the sealant into the gap so that it goes all the way to the tape sticking the window. This takes time and is messy and will require a major cleanup with solvent after it's done. Plexiglass can only have varsol or mineral spirits used on it. But for the fiberglass you can use Lacquer thinner because it so much stronger and faster. You can touch the edges of the windows with Lacquer thinner but not the flat surfaces. This is the hard part because it's easy to spill lacquer thinner on the window surface. Lacquer thinner will mark the surface of the see thru areas of the plexi if that happens. If it happens and marks the viewing surface it can be polished out with compound. As you will learn Lacquer thinner cleans so much better than varsol. You tend to use very wet rags with lots of solvent on them.

You will need 2 large tubes of Dow Corning 795, 3 small blocks of wood, plus 3 x 3/8" wide woods shims per side, you can use the same blocks on the other side afterwards.  Lots of paper towel and rags and try not to do this in the sun or the sealant will skin too quickly. We did it with the cover still on the boat. Goodluck!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2020 at 8:33am
Hi Bill,
I did not see mention 'tape' in previous posts. Could you say more about this tape?
Also, the window I got is of original size. I was planning to use 100% adhesive until I saw your recent post. I'm wondering if you've done a window using just adhesive.
Thanks,
John
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2020 at 9:56am
I can't seem to locate it online but in short it's a double sided foam/neoprene tape that is approx 1/4" wide by 1/4" thick. (black colored tape is best) The tape is placed around the perimeter of the deck cutout covering all the fastener holes and it holds the window in place while leaving a 1/4" gap that will be filled by the sealant. Once the fastener holes are covered you will see it's very close to following the cut out edge in the fiberglass... and you trim the edge of the tape following the cutout edge of the fiberglass.

So if you now stick your window into place the tape holds it in place perfectly so you can now fill the 1/4" gap with the sealant. Once the sealant cures you have a leakproof set of windows that won't crack. Yes we have done this on a few boats with total success.

The dilemma is that the measurement from the cutout edge of the deck to the edge of the original window outside perimeter is now reduced because of the tape. So the area that holds the sealant is not wide enough to hold enough adhesive sealant to hold the window in place. Hence the larger window. 

  






Edited by Bill Layton - 31 January 2020 at 9:57am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ron Waterson Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2020 at 10:28am
Unaware of Bill's process, I replaced my windows last fall using a similar process.  3m VHB tape is what I used.  Major keys to success are to get a tape thick enough that your caulk can get in the gap created. Make sure you are placing the new window in the correct place (temp blocks and such as Bill suggests) because once the window hits the tape, its for good.  You can not adjust the window on the tape.  Google around for using VHB tape on boat windows and you will find some more info.  Surface prep is important too.  There are a couple of 3m spray on primer products that help. 
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