View Full Version : Need help sealing cabin glass
10-13-2004, 06:53 PM
I am new to wood boats and the correct techniques and materials to make proper repairs. This site seems to have the most abundant knowledge on this subject I have seen and I have been searching lots. I searched this site for quite a while and haven't found the answer to my questions although I am quite certain it has been asked before. I have a 1968 Chris Craft Cavalier. The windows in the front cabin were leaking so I removed one of them so far and cleaned the groove as good as I could (needed a tow truck to remove some old 5200) and sanded with some 40 grit before applying one coat (so far) of CPES. I have cleaned the glass with windex and I am ready to re-install. I am unsure of what product or products to use for best results. I would like to have this back together soon so I can do the other window. I need to get the tarp off this boat so I can install my new Dickenson Newport heater.
After some reading on here in other threads I purchased some Dolphinite Mahogany bedding compound for use on the inner frames of the sliding windows and was thinkin that would be of some use here. Problem is that these windows are not held in by anything but goo. There were about 12 products used to hold this in when I removed it including some screen door double-backed foam adhesive strip (good lord). I hate to get long winded but I don't know how else to get my answer. I included a sketch of the cross section and letters A,B,& C for areas needing some type of sealer. Maybe all three areas will use one thing, I don't know. My thought, however ill-conceieved was to use the Dolphinite bedding compound for area's A & B and then use something like 3M 101 polysulphide sealer for area C. I read the topic on one part polysulphides and if they are discouraged, I need to know what works and comes in white. Any and all suggestions and comments welcome. I don't like to do things over because of ignorance. http://www.nwoffshore.com/images/windsheildframe.jpg
[ 10-13-2004, 11:02 PM: Message edited by: Jim Pooler ]
10-13-2004, 07:51 PM
I am surprised this hasn't been covered before, at least that I can find. I did find this thread, though: Sealing portlights - 1961 Chris Craft Constellation - carvel planked hull (http://media5.hypernet.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=002541)
I imagine one of the experts will be along shortly. Until then, let's talk clean glass.
You can tell when glass is really clean easily - water "sheets" instead of "beads". The best way I know of to get it really clean is Bon Ami powder; applied with a damp sponge and polished off with clean cloth. General Motors dealerships carry Bon Ami just for this purpose.
By the way, you might want to do your final testing with distilled to prevent recontamination.
I'm going out on a limb here, but I really think you want a strong AND elastic adhesive in Area A. I don't think that little rim of adhesive at C is going to retain the glass in a real blow.
Hopefully someone more knowledgeable will happen along shortly...
10-13-2004, 09:11 PM
Wow, I guess clean glass was harder to achieve than I thought. Can you still get Bon Ami in most stores?
Yes, I am concerned about it staying in too. Even with all the crap the last guy put in, it still had some movement. I mean movement as in I push on the glass and it separated from the seal. I wonder if the 3M polysulfide in B & C would work. I'm sure someone will pop in here soon with some answers.
[ 10-13-2004, 09:24 PM: Message edited by: Jim Pooler ]
10-13-2004, 09:34 PM
I just found an old article about repairing window leaks and it says to have some 3/32" shims under the glass, lay down some "silicone based window glazing" specifically designed for this purpose. (I don't like silicone) It says to let put some shims under the glass too so it doesn't rest on the frame and then let the bedding set up overnight. Then come back and finish glaze the exterior. Well that all sounds good except for the silicone. The 3M 101 application calls out windshields. Will it work or is there anything better I should use instead. I guess I'll go down to the boat and see if any birds have set-up house in the boat since the window has been taken out. :D
10-13-2004, 11:19 PM
Most any household scouring cleanser will work, Jim. Its the calcium carbonate (in most like Ajax and Bon Ami) that abrades any contaminates off, yet is softer than the glass, so they won't scratch.
A new breed of elastic polyurethanes (3M 5200 is one) are out now and formulated for elasticity as great glass sealants and are available at home centers, in a variety of colors like white. Try PL Polyurethane window and door sealant. Easily matches the performance of marine sealants but at a fraction of the cost. They are as elastic as silicone, but won't contaminate.
A good trick is to dry fit the glass, then mask off the wood frame AND the glass, running the masking tape right to where you want the sealant edge. Then pump in your sealant, press in the glass to adequate squeeze-out, then re-apply where needed for the outside beads, then use your finger or rounded putty knife to tool the wet sealant into a nice fillet.
When it looks good, peel off the masking and let dry - looks super professional.
10-14-2004, 03:32 AM
Good idea about the masking, I hadn't thought of that. Well it looks like the 3M 101 takes almost a month to cure Geeezzz. You would think that nobody ever has to do this anymore. Interesting that 3M does not recommend any of their products except the 101 for installing glass but you have to wait 2-3 weeks for cure at 70 degrees. The 4000, 4200, and 5200, all available in a fast cure option are not recommended for glass installation where there is not a mechanical means of holding the glass in. I can't believe they would think the 5200 would not hold the glass in.
[ 10-14-2004, 04:16 AM: Message edited by: Jim Pooler ]
10-14-2004, 09:29 AM
It's your boat of course, but personally I don't like the idea of glass being held by only adhesive. Yes, I know there are miracle goops out there that are all wonderful, but glass is such a weak area in a boat with regards to fresh water intrusion, if it were my decision, I would retrofit a mechanical system to hold the glass in place, and use the sealant only as a bedding compound.
I would, perhaps, set inside and outside a nice and meaty 3/8" thick border that overlapped the glass by something like 1/8", then use fancy looking s.steel/brass/bronze (depending on the aesthetic desired) carriage bolts with lock washers, nip the ends and 'sweat' on some solder. This way I could easily control the amount of pressure exerted on the glass, and I could use 3M101 all day long as my bedding compound if I desired, since the glass isn't moving.
If I was concerned about showing metal fasteners on the outside, I would increase the outer plate's thickness to 1/2", and counterbore the fastening holes down to 1/4". using very flat headed bolts so that I could epoxy in bungs. I know you don't usually epoxy bungs, but in this case I believe it would be better given that there are so few and you really do need gap filling. Why not rivets? Well, that would be a real pain in the butt to maintain later on.
Good luck in your efforts!
10-14-2004, 10:21 AM
What I did on my 1970 egg harbor.
Cleaned up the wood frame
coated the wood frame with good old epoxy
sanded it smooth
placed window into frame
went to home depot
bought polyurethane window and door sealant in white
ran caulk into channel only between glass and outside wood, I did not seal the inner glass side to the wood, this will make it easier to remove if you have too.
took an ordinary plastic smooth spoon and carefully dragged a concave bead all around the window.
Let it dry and cleaned up any excess with razor blade.
It holds against rain and water now for 3 years so far.
This adheasive caulk is strong and will not fall out!
10-14-2004, 12:49 PM
Amen, brother (Sdowney)! Couldn't have said it any simpler myself.
BTW, Jim, its a good thing that the 3M101 dries slow - As a chemist, I know that that slower drying polymers generally shrink less and retain adhesion better. The polyurethane spoken above dries slow also, but only two - three days - better than 3 weeks.
I have to respectfully disagree, Timothy - the least amount of mechanical fastening for glass the better. I manufacture exotic, color-changing glass for a living and I routinely write spec sheets on installation that my warranty hangs on, and the reason that any hard fastening points is bad (even moulding encapsulation) is because any stress applied to the glass will focus the stress on the most immovable point (like the tightest carraige bolt in your description), thus cracking at that point - even if the bolt were 1" away from the edge of the glass. Screwing a backer mould against the glass, even if you have heavy sealant in the gap can often crack the glass during installation (I know from experience too many times) because you don't always know how perfectly flat the plane is that the glass lays against. Any twist and you got crack city.
If the glass is bedded where there is at least 1/8" of elastic polymer separating it from any hard point, that glass can handle a lot more flex before cracking, and never gets "torqued" out of flatness.
You gotta picture passengers holding onto the window frame in rough seas. No glass should ever be installed with fasteners of any kind, anywhere near it, let alone screwed-in backer moulding. Not necessary with todays polymers. Still love ya though, Tim - good posts generally.
10-14-2004, 01:03 PM
Thank you for all your replies. I will probably go down to Home Depot and look at that PL polyurethane. There apparently are no marine products made for this purpose. :rolleyes:
I think 3 weeks to set is a little much especially when it is starting to get colder out. I don't think it's a good idea to lay the glass down on the wood though. I know for a fact that the wood frame is not completely flat. I also think you need the glass suspended from the frame with the goop to allow for the flexing of the frame.
[ 10-14-2004, 01:04 PM: Message edited by: Jim Pooler ]
10-14-2004, 02:57 PM
If you want leaf-proof window panes...then you'll have to use Uerathane adhesive. The very big down sideof this is, that it is vurtually unremoveable. Which means....if the glass pane breaks then you will have to work your *** off in order to replace the glass, and perhaps, building a new frame would be less work.
Uerathane is the adhesive for auto glass windshields. The going rate around here is $8 a tube. Find a local auto glass installer and buy a tube.
Sometimes its worth sealing in glass permanately and taking the chance of never needing to replace it. smile.gif
10-14-2004, 03:32 PM
The reason silicone is the standard for sealing or bedding glass is that it is very resistant to UV, and bonds well to the glass. Urethanes (notably 5200) in general are not good in sunlight, and the glass refracts the UV to the bonding agent, even under the glass or trim. This is also a problem with epoxies used to seal the wood under the glass. The main drawback to silicone is that paint and varnish don't adhere to it. The solution is to mask carefully, and don't get it where you don't want it--it doesn't come off easily if you do. I'd seal the edges with some aluminum powder in the epoxy, and use silicone for bedding.
10-14-2004, 03:32 PM
Be careful about UV resistance too. Though I don't know personally, I've heard that for example, 5200 degrades with extended UV exposure.
I'd be certain to get a product meant to bed transparent materials in the bright sun, not one meant to bed opaque materials.
10-14-2004, 04:49 PM
Sikaflex 296 is made specifically for windows on boats. I've never used it, so I can't vouch for it.
10-14-2004, 08:09 PM
hi, my 67 chriscraft front cabin windows are just held in with what looks to me like a hard but flexable gunk. the inside has thin rubber gasket type shim around the whole window frame.. i dont have any water leaks so im leaving mine alone for now
10-14-2004, 11:27 PM
Yeah I read about the Sikaflex 296 specifically made for windows. Why in the world did they only make it in black? :rolleyes:
The 295 UV will work for glass but is specifically intended for polycarbonate or acrylic windows. Nobody had any either.
Right, wrong, or indifferent, I went and bought some of the PL polyurethane. At least it is made for windows and is white. It also doesn't take 6 years to cure. The 3M 101 I put on so nice 2 days ago still isn't tack free yet. It isn't so nice now. :(
I laid the window into the bedding with 1/8" shims under it and shimmed away from the sides of the frame. I am going to let it set-up over night. I plan to use the same stuff for exterior glazing and hope for the best I guess. I sure am disappointed I couldn't find something that didn't have something wrong built into it. It's hard enough to keep things fixed as it is.
10-15-2004, 01:28 AM
"I sure am disappointed I couldn't find something that didn't have something wrong built into it."
Welcome to the world of engineering smile.gif . Making nerve-wracking decisions is the whole point, it sometime seems.
The good news is that you have mastered the key phrase: "Right, wrong, or indifferent, I..."
PS: They only make it in black because black usually has the best shot at UV resistance (I suspect carbon is the key; damn I miss The Chemist)
PPS: If polyurethane repair scenarios dominate your nightmares, take solace in the experience of the auto-windshield R&R guys - fine wires will separate the joints; clean & sharp tools will prepare the surfaces for re-joining. And if the above fail, heat helps.
10-15-2004, 04:01 AM
Thanks Ross, I am sure this is all intended to build character. ;)
Is "The Chemist" no longer around? His posts always amazed me but seemed to bring some sanity back into the threads.
[ 10-15-2004, 04:03 AM: Message edited by: Jim Pooler ]
10-15-2004, 09:38 AM
I'm certainly not "The Chemist" but I have a couple patents in polymer science, so here's a little correction on the UV resistance concept:
Black is actually not the most favored color for UV resistance - white is. The black color turns the suns UV light energy into heat energy, which accelarates the polymer breakdown by releasing free-radicals (sheared-off electrons, dismantling molecular chains). Its not just UV that generates free-radicals.
Next time you're in a parking lot on a sunny day, look for white vehicle and touch the hood. Then find a black one and do the same. If the white hood is cold, then the black will be hot. If the white hood is warm, you'll burn your hand on the black one.
White reflects all the heat away - hence the best pigment for any polymer longevity.
10-15-2004, 12:12 PM
These are the products that I have tried over the years...they ALL failed.
Silicon's from Home Depot
Silicon's from West Marine
BoatLife polysulfide, 1 part
BoatLife 2 part
The only thing that I have EVER put on a window pane in a wood frame that did not leak is/has been automotive windshield adhesive called "Urethane". I buy from both "Royal auto glass" and from an independant istaller near home. The extra tube I had left over is "Swedish" made I believe. I'd have to read the tube again to be certain...but I believe it is made in Sweden. ALSO, it does have a brush-on primer you can use with it.
I'd wasted too much time with too many products that did NOT work and said to myself..."self, to **** with the window frames, glue the sucker in there and be done with it!"
I am still very happy with each and every window pane. smile.gif
10-15-2004, 01:39 PM
I do not doubt the heat absorption side of things, but the UV resistance may to be a separate issue.
A few data points from which my opinion emerges:
Cabot Corp White Paper (http://www.cabot-corp.com/cws/businesses.nsf/8969ddd26dc8427385256c2c004dad01)
Carbon black is one of the most widely used and
most effective ultraviolet (UV) light stabilizers for
plastics applications. Several important segments
of the plastics industry rely on carbon black for
UV stabilization of weather-resistant products,
including telecommunications and power cable
jacketing, plastic pipes, geosynthetic membranes
and agricultural films..."
Carbon black (CB) is more than a colorant. In
addition to its tinting power, electrical or filler
action, it provides plastics with a long-term and
low cost UV protection, stabilising polyolefins and
other polymers against sunlight [1-4]. The UV
protection property of CB is dependent on its
morphology, loading and surface chemistry.
However if the CB is poorly dispersed or diluted,
its full benefit will not be realized."
Polyethylene protection from UV degradation can
be achieved by adding appropriate additives such
as antioxidants, typical UV stabilisers (i.e. HALS)
or carbon black. Parallel to its colorant function,
carbon black is known to act as a UV absorber
and antioxidant [8, 9]: it offers the best UV
protection for many materials, by absorbing /
screening out damaging wavelengths, and by
inhibiting photo-oxidation via its surface chemical
properties. The following experimental data
highlight morphology, dispersion and dilution
influence on carbon black UV stabiliser role."
From sdplastics.com/ultravioletresistance (http://www.sdplastics.com/ultravioletresistance.html)
"Nylon (all types)Unpigmented resins will degrade upon exposure to sunlight evidenced by discoloration and embrittlement. Formulations containing carbon black particles provide the best UV stability."
"PBT Polybutylene terephthalate (PBT) (also known as Hydex® 4101, Valox®, Celanex®, Ultraform®) is “inherently” UV resistant. Supplier data indicates that there is little degradation in mechanical properties after several years of exposure. Black pigmented resins have better property retention."
"Polysufone Polysufone (Udel®) will experience some degradation upon exposure to sunlight. Black pigmented formulations are recommended for improved performance."
I realise that the elastomers under consideration for the immediate problem are not addressed here, so It is entirely possible that my understanding is not applicable.
10-15-2004, 05:58 PM
I've decided to just break out my trusty mahogalass welder and lay a big bead all around. That should do it. Wha-da-ya think?
My other thought is to just get rid of the glass and build a seat on deck. Don't know if it would look that good on a Cavalier though.
10-25-2004, 09:08 PM
I received an email addressing this topic and thought I would share for the benefit of anyone else inquiring on this topic.
I'm Steve Smith.
I make CPES, and as a product manufacturer I cannot post on the Forum, since commercial use or self-promotion is not permitted by forum rules, and my very name is self-promotion due to my business. I am therefore replying to you directly.
3M makes 4200 and 5200, and both are available in black or white. UV resistance of either will be adequate, although black will soak up more heat from sunlight. More heating means more physical expansion of the elastomer, and thus more stress on the glass and wood.
Wood trim on the outside, around the windshield edge, blocking the UV from going thru the glass and attacking the sealant-glass bond,, is recommended and will give a nice appearance.
The wood needs to be primed with Clear Penetrating Epoxy Sealer(tm), also known as CPES(tm). Allow it to dry at least a day, if the wood is sound, or several days if the wood was somewhat deteriorated and soaked up quite a bit of CPES. The solvents should be largely dissipated before applying filers or sealants.
The glass needs to be cleaned with an alkaline solution, as pH above roughly ten dissolves a few layers of molecules of glass, and you then have a chemically clean surface which water will sheet off of. A strong solution of Cascade or similar automatic dishwasher detergent
will do. Abrasive cleaners are optional, if for instance silicone
sealants were used.
Use 4200, as it is a lower-modulus sealant than 5200 and for a given amount of inevitable structural movement it will develop less stress on the adhesive bonds.
4200 and 5200 are isocyanate-terminated urethane sealants, and should
bond just fine to chemically clean glass. They also will bond very
well to my CPES, even if fully cured and a month old.
As for joint design, put in some wood-or-whatever spacers, and pull them out before the sealant is fully set, and backfill those holes. The ideal joint design has the glass floating in a bed of elastomer on all sides. A reasonable elastomer thickness in your application is an eighth to three-sixteenths of an inch, if using 4200. I am on the Chris-Craft list if you need more info.
10-26-2004, 05:33 PM
Oh, oh! HAS THE CHEMIST BEEN "OUTED?"
10-26-2004, 07:42 PM
I have never seen such befuddlement about sucha simple deal as this. Do you have that many problems with the windows at home? Sheesh.
10-27-2004, 02:00 AM
Well thanks Gary for minimizing my issue. I didn't see a simple response from you about how easy this is. I don't think house windows would fall into the same category. That is unless you take your house out four wheelin.
This may not be rocket science, but since I have not performed this repair before I thought I would ask those who have so I can do it right. Thank you for your participation.
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