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chorussf
03-28-2015, 07:46 PM
Hi,

I have a few cracked "main saloon" windows on a Kettenburg 38. They are oval shaped and about 2 square feet in area. There are four total and because of scratches I'm going to replace all four even though just two are cracked. I'm wondering what the best type of marine glass is for this type of application. Also where is this sourced, and how is it cut--do I take templates or what?

Second question is about chrome on bronze rimmed glass oval portholes. The chrome has broken down and is a unholy mix of rusted chrome, dirt and verdigris presents a pretty gnarly mix. What is the best way to refresh? Should I try to extract the glass and have them refinished or can this be done with the glass in? Any advice would be greatly appreciated.

Cheers & thanks in advance.

Bradley

shade of knucklehead
03-28-2015, 10:20 PM
Hi,

I have a few cracked "main saloon" windows on a Kettenburg 38. They are oval shaped and about 2 square feet in area. There are four total and because of scratches I'm going to replace all four even though just two are cracked. I'm wondering what the best type of marine glass is for this type of application. Also where is this sourced, and how is it cut--do I take templates or what?

Second question is about chrome on bronze rimmed glass oval portholes. The chrome has broken down and is a unholy mix of rusted chrome, dirt and verdigris presents a pretty gnarly mix. What is the best way to refresh? Should I try to extract the glass and have them refinished or can this be done with the glass in? Any advice would be greatly appreciated.

Cheers & thanks in advance.

Bradley

We usually use safety glass from the local glass shop. They would need a template or the old window. Sometimes the edges have to be ground if it goes in a rubber window molding. lately our local place has been really slow on turnaround so call them and talk to them before you take the old glass out. Depending on the installation they might have to be cut exactly right. Pictures of your windows would help.

Getting things re-chromed is costly. You could take them out and polish the chrome off and just have brass portlights. Its pretty time consuming. The glass would need to come out to do that. Its all a question of time and money...

MN Dave
03-29-2015, 01:27 AM
You probably can't strip chrome with the glass in place. Maybe shouldn't is a better word.

Chrome is easy enough to strip but you wind up with a bucket of chromium containing hazardous waste that would cost more to dispose of properly than it would to have the parts stripped by a plating shop that is equipped to handle the disposal.

Muriatic acid will do the job, but it will leave the nickel underplate behind. Nitric will take off the nickel, but it is harder to get, and will also dissolve bronze while boiling off a cloud of toxic red fumes. Not to mention an even worse bucket of hazardous waste to dispose of.

A plating shop can also put a nice thick layer of copper plating on the part that can fill in the pitting and be sanded and buffed to level off the corrosion. That is part of the normal chrome restoration done on a pitted part. It is getting harder to find chrome plating shops due to environmental woes.

slug
03-29-2015, 01:58 AM
Chrome plating is very difficult because of environmental issues. All the small shops that I used to deal with no longer chrome plate. I must now ship my pieces to be plated and its a 6 week turn around.

If your windows cracked there must be a structural issue that is causing the stress. Double check that the windows were installed correctly and that tthe structure that the frames are set into is free of stress.

As for glass I use a specialist. I create a plwood form, he double checks that the form is exact, then supplies the glass.

Best to ask you glass supplier for advise. Ask him why the glass cracked and for bedding counpound or gasket suggestions.

chorussf
03-29-2015, 04:10 AM
Wow thanks guys. Great advice. Slug the structural problem unfortunately was 1) an errant bowsprit of another boat during a race, and 2) an overzealous heat gun!

Thanks you all....

Bradley

slug
03-29-2015, 04:17 AM
Yah...bowsprits are a public menace . Keep a chainsaw handy and trim any nearby bowsprits down to snubnose size.

sheerline
03-29-2015, 04:28 AM
I was on my mooring when a passing yacht decided to go and U turn around the bow of me. He miss judged the wind and tide and impaled his rail on my bowsprit. He managed to get off by increasing HP to the prop which tore away my stb shroud. As he went passed he shouted and waved his fist that it was my fault for having "THAT THING" stuck out. As you can imagine a very colourful reply was given and the name of his yacht written down. I earned a pretty penny for his stupidity.
I LIKE BOWSPRITS :p

Trev

MW Jones
03-29-2015, 10:57 AM
I concur that safety plate is the best choice. It is stronger than tempered glass. When you fit the glass to the opening it is best to have a loose fit that allows for contraction and expansion. Sika makes some excellent caulking for bonding to "mineral glass" and "organic" glass(acrylic and polycarbonate) 295UV and 296. if you want a color other than black and white, I've used 221 a urethane sealant and 521UV a one-part Silane Terminated Polyurethane Hybrid (whatever that means) with success. Research the properties at: http://usa.sika.com/ They also have installation guide lines, not so critical for panels that are held in place mechanically.

A thicker section of caulking is less likely for failure than a tight fit, much more critical in large panels of real glass(mineral) and plexiglass(organic) which require 1/8" and up for large panels that are used on the big Plastic Boats that rely totally on the adhesive caulking to hold them in place.

Bob Cleek
03-29-2015, 02:42 PM
I concur that safety plate is the best choice. It is stronger than tempered glass. When you fit the glass to the opening it is best to have a loose fit that allows for contraction and expansion. Sika makes some excellent caulking for bonding to "mineral glass" and "organic" glass(acrylic and polycarbonate) 295UV and 296. if you want a color other than black and white, I've used 221 a urethane sealant and 521UV a one-part Silane Terminated Polyurethane Hybrid (whatever that means) with success. Research the properties at: http://usa.sika.com/ They also have installation guide lines, not so critical for panels that are held in place mechanically.

A thicker section of caulking is less likely for failure than a tight fit, much more critical in large panels of real glass(mineral) and plexiglass(organic) which require 1/8" and up for large panels that are used on the big Plastic Boats that rely totally on the adhesive caulking to hold them in place.

Very true. The expansion joint is particularly important when "glass" is set in wood because of the expansion of the wood frame. If a metal or wood trim ring is placed over the joint, I've found that common silicone sealant (which would otherwise degrade quickly in sunlight) is very good for the purpose because it is very flexible and compressable and remains so over a long time, unlike many other "tube goops," which may have a tendency to harden up over time. Silicone is also rather easy to remove when the time comes.

slug
03-29-2015, 05:04 PM
If there is any paintwork near silicone you will be cursed for life.

not sure what your frames and windows look like but the typical way of developing the proper joint gap to prevent a caulk starved condition is to use double sided foam tape on the inside edge of the frame and small rubber teardrops around the perimeter of the frame to keep the window centered in the frame and off the edges.

these rubber teardrops are available at most hardware stores. 3m. Bumpon is a common choice.


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chorussf
03-29-2015, 05:56 PM
Slug and all,

Thanks for the great suggestions. Here's a link that shows what the windows look like (the two big oval windows) http://i.ytimg.com/vi/wVuWPCUml1Y/maxresdefault.jpg. This is a PCC but the layout is roughly the same scaled down as the K38.

The windows are quite simple. The glass is just set into a rabbeted sill (in a two inch thick piece of mahogany) from the inside and then a wooden eschutcheon covers the rabbet and serves as a frame.

Here's an image of the look from the inside (again not my vessel but the model I'm striving for in terms of look).

https://plus.google.com/photos/100623877013429039202/albums/5812270345562074705/5953219673540702706?banner=pwa&pid=5953219673540702706&oid=100623877013429039202

Slug, can you explain the setting of the glass a bit more given the picture. I'm having a bit of trouble imagining how you do that.

Cheers, Bradley

Bob Cleek
03-29-2015, 06:19 PM
If there is any paintwork near silicone you will be cursed for life.

not sure what your frames and windows look like but the typical way of developing the proper joint gap to prevent a caulk starved condition is to use double sided foam tape on the inside edge of the frame and small rubber teardrops around the perimeter of the frame to keep the window centered in the frame and off the edges.

these rubber teardrops are available at most hardware stores. 3m. Bumpon is a common choice.



Absolutely. Paint or varnish won't stick well at all to silicone caulking goop. I almost said that in my post, but then figured there wasn't going to be much danger of that if one covered it with a trim ring. Those "rubber" buttons they sell as pictured above are used as "feet" for coasters, etc. or as "bumpers" on kitchen cabinets. Actually, they are made of silicone, just the same as what you get when silicone caulking goop cures. The advantage of a continuous bead of silicone goop rather than the "buttons" is that it also seals the window against leakage.

chorussf
03-29-2015, 06:24 PM
Slug and all,

Thanks for the great suggestions. Here's a link that shows what the windows look like (the two big oval windows) http://i.ytimg.com/vi/wVuWPCUml1Y/maxresdefault.jpg. This is a PCC but the layout is roughly the same scaled down as the K38.

The windows are quite simple. The glass is just set into a rabbeted sill (in a two inch thick piece of mahogany) from the inside and then a wooden eschutcheon covers the rabbet and serves as a frame.

Here's an image of the look from the inside (again not my vessel but the model I'm striving for in terms of look).

https://plus.google.com/photos/100623877013429039202/albums/5812270345562074705/5953219673540702706?banner=pwa&pid=5953219673540702706&oid=100623877013429039202

Slug, can you explain the setting of the glass a bit more given the picture. I'm having a bit of trouble imagining how the tape and bumpon is used in my application. Thanks alot for the help much appreciated.

Cheers, Bradley

chorussf
03-29-2015, 06:32 PM
Yeah no paint or varnish between the glass and the sill; but I do definitely need sealing from leakage. The current windows leak quite a bit--another reason I wanted to restore them. So yeah I'm having trouble understanding the proper use of the bumpons.

MW Jones
03-31-2015, 04:37 AM
The buttons are used as spacers between the glass and the frame so that you get an even thickness of you caulking. If your glass is 1/4" with an 1/8" thick button, your rabbet should be 3/8".

The foam tape is used the same way. and is used on the inside edge of the frame next to the opening. If your rabbet is 3/4" wide by 3/8" deep you could use mounting tape that is 1/4" wide by 1/8" thick, to leave your caulking 1/8" thick by 1/2" wide. Works well with larger panels, and especially with plastic panel it help with keeping the inside of the panel clean so less danger of scratching the panel during clean up.

You can make your own out of the caulk you are using by spreading some out on something it won't stick to like plastic and let it cure, and then cut it to the size you want.

for what it worth I would not use silicone, it bonds great to glass, but not so well to wood and paint.

MW Jones
03-31-2015, 05:00 AM
The foam tape would not work in your application, as it is would be used when the glass is set in a rabbet from the outside of the boat. With your set up you want your spacers set at the edge of the glass and solid caulking on the exposed exposed joint.

I would seal the inside of you rabbet with epoxy, ( one coat to penetrate, one coat with some barrier coat additive) allow to cure , and sand smooth. And the set the glass using Sika 296 made to bond mineral glass to a frame. If you are using an acrylic panel use sika 295 UV made for organic (plexiglass/lexan) glass. If you use plastic use cast acrylic rather than a polycarbonate, as the acrylics hold up better to UV.

Paul G.
03-31-2015, 05:29 AM
Stripping the chrome is doable, you need sulphuric acid and a 12v battery plus a jumper lead and a decent sized stainless bolt, first make a 50/50 acid solution by adding acid to the water NOT the other way around. Connect your chrome to the + and the bolt to the - and the chrome should bubble away pretty quickly. I did a lot of chromed bronze fittings and they turned out great. Do it with gloves, goggles, mask and old clothes outside. The residue is toxic for sure but the amounts are so small that disposal should not be an issue provided you dont chuck it down a drain or a waterway. Its been a while so maybe the + and - are reversed, anyway its very very simple to do.

slug
03-31-2015, 06:14 AM
Remember to prime the glass with the correct primer for your system

i use Sika. Black primer is common. The black hides any bubbles that form in the caulking to glass joint and offer UV protection to the cauliking

a "V" cut caulking tip produces a better joint

General glass bonding guidelines


http://fr-marine.com/Images/UpFile/201171292438717.pdf


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dnyknot
03-31-2015, 06:10 PM
Q , my boat has lexan ( ? ) windows which need to be replaced , the bedding compound looks to be dolphinet ( ? , we always call it dull knife dont know why ) any ideas on removing the windows without trashing all my varnished cabin sides ? . They have been in there for 52 years , and they are set in a rabbited recess , I was thinking of a hot knife and putting a back up strip to keep the cabin sides from tearing out . Any other ideas ? thx
dn

Paul G.
03-31-2015, 09:09 PM
Try a piano wire with one person inside and one outside and pull it around. It how they do it here.

chorussf
04-01-2015, 01:34 AM
Thanks for all the great ideas guys. I had a good time today removing the old glass. Came out fairly easily with only about 4 hours of work. I'm going to route clean the rabbets tomorrow, apply MW's treatment to the clean edges, send the templates off to the glass co, cut the new eschutcheons, sand the inside and outside of the cabin house to get it ready for eventual varnish, install the glass, install the eschutcheons, varnish wood until the cows come home. This should take two to three hours ;)

Today though while remove the glass I had a bit of archaeology exploring the past of the boat through the many ways the glass had been reset in the past. One or possibly two windows appear to be original. They are extra thick and solid and the eschutcheons are old and grey and full of sleep. Anyway after taking off what I believe to be the oldest windows I noticed that the bedding compound for these windows at least at the top of the window was still supple and pliable. It moved like a stiff gum between my fingers. I believe this dark brown tinged with red material is 60 years old Any one have any idea what this might be?

Anyway what an exploration!

Cheers, Bradley

chorussf
04-01-2015, 04:42 PM
MW Jones,

Thanks for the details. I suppose you leave the buttons in there encased in the goo for all time?

And that probably doesn't matter right?

Bradley


The buttons are used as spacers between the glass and the frame so that you get an even thickness of you caulking. If your glass is 1/4" with an 1/8" thick button, your rabbet should be 3/8".

The foam tape is used the same way. and is used on the inside edge of the frame next to the opening. If your rabbet is 3/4" wide by 3/8" deep you could use mounting tape that is 1/4" wide by 1/8" thick, to leave your caulking 1/8" thick by 1/2" wide. Works well with larger panels, and especially with plastic panel it help with keeping the inside of the panel clean so less danger of scratching the panel during clean up.

You can make your own out of the caulk you are using by spreading some out on something it won't stick to like plastic and let it cure, and then cut it to the size you want.

for what it worth I would not use silicone, it bonds great to glass, but not so well to wood and paint.

MW Jones
04-03-2015, 07:47 PM
correct, and slug is correct about the primers , they are more expensive than the caulking. And the V-cut in the caulking tube also.

neatness counts here, the object of the game is to be as clean as possible and use as little cleaning solvent as possible. Tape off areas to be protected, and wear gloves, change as needed and keep a rag damp with solvent (denatured alcohol works well) to keep your gloves clean. Do one complete dry fit before starting. Dry weather and shade are important. Your panels are small enough that it should't e too difficult. You could set the glass, with some temporary cleats to hold it flush to the inside of the cabin, and do the interior trim in a separate step. It will take a little more time but fewer part with sticky stuff to handle in each step.

chorussf
04-03-2015, 08:26 PM
MW thanks for the advice. I like the idea of doing the trim as a separate step with some type of shores or clamps.

Thanks, Bradley