Sealants Summary ...

[TinTin]

... added Trempro 635 to Windows/Trim/Rubrail

For wheel wells/underbody:

Vulkem 116
Trempro 635 Grey
Sikaflex 221 Black (use Eternabond spray cleaner to prepare surface)
Adseal Premium Quality Sealant Grey

Roof:

Sikaflex 221 White (for roof seams, seals and bonds. Use Eternabond spray cleaner to prepare surface)
Sikaflex 715 (around fans, vents, skylights ... self-levelling)
Adseal Premium Quality Sealant White
Dicor self-levelling sealant

Windows/Trim/Rubrail:

Sikaflex 221 Grey (seals and bonds. Use Eternabond spray cleaner to prepare surface)
Parbond Grey or Clear (small hand tubes, prep and clean-up use cosmoline remover)
Trempro 635 Grey
Loctite® PL® S40 Polyurethane Window Door and Siding Sealant

Small seams (between aluminum panels)/Exterior Lights:

Acryl-R (available in cans from Airstream store. Use applicator or disposable syringes to apply)

Rivet sealer:

Captain Tolley's Creeping Crack Cure

[Fly at Night]

The FaN has endured hot, hot, summers, freezing winters, and enough rain to drown an ox; am happy to report that it has not leaked for over three years. (There were two small consecutive leaks the first year). I asked the dealership what the heck they used as sealant, because it is obviously working. Parabond!

[1947liner]

TinTin,

Also noticed that VTS feature 'butyl tape' for windows, similar to the original product,(they also have a good descriptions of which mastic to use where, of course to make sure, a call to them or any other supplier such as RV Centre for advise would be my first port of call). Personally I would only use a bonding sealant such as Sikaflex when:
1) I don't anticipate to have to remove the parts, ever.
2) I can get to the seam with a knife or cutting wire.
3) There is no other mechanical fitting(rivets/screws) holding the parts together

(As always, there are some exceptions to the above. )

[lewster]

Originally Posted by 1947liner

TinTin,

Also noticed that VTS feature 'butyl tape' for windows, similar to the original product,(they also have a good descriptions of which mastic to use where, of course to make sure, a call to them or any other supplier such as RV Centre for advise would be my first port of call). Personally I would only use a bonding sealant such as Sikaflex when:
1) I don't anticipate to have to remove the parts, ever.
2) I can get to the seam with a knife or cutting wire.
3) There is no other mechanical fitting(rivets/screws) holding the parts together

(As always, there are some exceptions to the above. )

Butyl tape is a bedding agent that is placed under or behind flanges and bases of items to be mounted by other mechanical means. You would use butyl tape to line the bottom of the mounting flange of a Fantastic Fan prior to placing it on the roof and then screwing it down, or under a roof termination vent for your grey or black tank. A covering sealant top coat (usually self leveling) is still required.

Another place butyl tape is used is when mounting a water heater. The mounting flange gets a layer of the tape prior to placing the heater into the opening in the sidewall. Screws are then used to secure the heater to the wall, and a a semi rigid sealant (SikaFlex 221) is then used over the seam.

[Starstream]

Tin Tin, Thank you for the list. Have this thread bookmarked. The list will come in very handy as we update.

Lewster, Thank you for the knowledge and application of the different sealants

Great Thread

[subfan1]

Bookmarked


Sent from my iPhone using Airstream Forums

[thumbelinadj]

Thank you! I was just reviewing my shopping list today for the next stage.

[perryg114]

So which sealants have the best UV resistance? Once these sealants see the light of day, they harden and crack or peal off. I am not impressed with the long term on Trempro-635. I have some that has already aged out in less than 3 yrs. It also cracks if you don't have it thick enough in areas that flex.

There is a clear sealant "Lexel" that has good UV properties but it yellows over time. It picks up dirt pretty bad. It has good adhesion and elongation but not much tensile strength. So it is not the greatest adhesive. It is also hard to work with. You get one chance with it. No smoothing it out after the fact. It is probably best applied with a syringe. This stuff with survive on a hot shingle roof. Trempro won't last a year under those conditions.


I expect the Lexel is similar to Acryl-R. You can buy the stuff at hardware stores but it is not cheap. It is solvent based which means you need to have good ventilation if you use it inside. Once the solvent is gone it should not outgas.

I like Parbond but it ages out pretty fast as well. It starts to crack from the outside in until it eventually turns to dust. I expect it would work well as a first coat followed by a more UV proof sealant.

Perry

[thumbelinadj]

Worlds Collide! Lewster is not only an excellent repairmen but an incredible summer roommate! Greetings old friend!! Dena

[lewster]

Thanks Dena! Let's take this to the private message side before folks get the wrong idea and start to 'talk' :-))


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[TinTin]

Originally Posted by perryg114

So which sealants have the best UV resistance?


Perry

I came across the 3M polyurethane sealants while doing a Google Search. They make a number of polyurethane products, but this one caught my eye. They are marketed as marine products, but may have applications for Airstreams:

3M 4000 UV fast cure, UV resistant,high performance adhesive sealant

3M Marine 4000 UV fast cure is a premium cosmetic sealant. It offers better UV resistance than most polyurethane sealants and comparable silicones. It is strong, paintable and does not exhibit dirt-collecting properties. 4000 UV has equivalent or better adhesion to most substrates, when compared with
3M 4200 fast cure, making it a great product for most above and below the waterline applications. Recommended when very high strength bonds are required.

I wonder if anyone has tried this or the other 3M polyurethane products?

[perryg114]

It only comes in black or white and it is about $20 a tube. It better be pretty good stuff for that. Not the right color for an Airstream. I am going to experiment with the Lexel at least it is clear. I know it has good UV properties.

Part of our branch at NASA does UV testing for space applications. We are the guys that analyzed the LDEF samples back in the 80's. I may ask around. Usually, RTV's (silicones) did pretty good but these were industrial versions that did not use Acetic acid as part of the curing process. Not many organics last long in space with the extreme UV and atomic oxygen.

I can also do my own UV test on the roof of my house on the top of my skylights. Trempro-635 turned into powder in about a year up there. I guess I could get some Silkaflex and put up there to see how it does. There is LEXEL up there now that was put on when the Trempro-635 failed and started to leak.

Perry

Originally Posted by TinTin

I came across the 3M polyurethane sealants while doing a Google Search. They make a number of polyurethane products, but this one caught my eye. They are marketed as marine products, but may have applications for Airstreams:

3M 4000 UV fast cure, UV resistant,high performance adhesive sealant

3M Marine 4000 UV fast cure is a premium cosmetic sealant. It offers better UV resistance than most polyurethane sealants and comparable silicones. It is strong, paintable and does not exhibit dirt-collecting properties. 4000 UV has equivalent or better adhesion to most substrates, when compared with
3M 4200 fast cure, making it a great product for most above and below the waterline applications. Recommended when very high strength bonds are required.

I wonder if anyone has tried this or the other 3M polyurethane products?

[perryg114]

From what I can tell Acryl-R and Lexel are similar type products. They are clear very flexible but have a gummy consistency even when dry. They are not easy to apply to small areas with a caulk tube and you don't get a chance to retouch the surface. They are both solvent release but don't out gas when cured. There is little or no strength to these. They seal but don't glue very well. They are soft sticky materials. They are great for places where there is movement. They also seem to have good UV stability which far exceeds that of polyurethanes and parbond.

The polyurethanes are much easier to work with and make a nice pretty bead. However, they only last a couple years in the south when exposed to sunlight.

Perry

[TinTin]

Originally Posted by perryg114

It only comes in black or white and it is about $20 a tube. It better be pretty good stuff for that. Not the right color for an Airstream. I am going to experiment with the Lexel at least it is clear. I know it has good UV properties.


Perry

Yes, the lack of colour choice pretty much rules this stuff out. Some of the other 3M polyurethane products do come in gray.

I like Parbond myself, but have no personal data yet on UV breakdown. One thing I like about it, opened tubes remain usable for many months (perhaps years?), while opened caulking tubes of other items (Sikaflex, Adseal) have a very short storage life, even when carefully sealed.

[TinTin]

Please give us a review of the Lexel™ after you've had a chance to test it. It appears to be readily available in stores and online, a big advantage.

[TinTin]

(added Lexel™ to the list)

For wheel wells/underbody:

Vulkem 116
Trempro 635 Grey
Sikaflex 221 Black (use Eternabond spray cleaner to prepare surface)
Adseal Premium Quality Sealant Grey

Roof:

Sikaflex 221 White (for roof seams, seals and bonds. Use Eternabond spray cleaner to prepare surface)
Sikaflex 715 (around fans, vents, skylights ... self-levelling)
Adseal Premium Quality Sealant White
Dicor self-levelling sealant

Windows/Trim/Rubrail/Exterior Lights:

Sikaflex 221 Grey (seals and bonds. Use Eternabond spray cleaner to prepare surface)
Parbond Grey or Clear (small hand tubes, prep and clean-up use cosmoline remover)
Trempro 635 Grey
Loctite® PL® S40 Polyurethane Window Door and Siding Sealant
Lexel™ Clear

Small seams (between aluminum panels):

Acryl-R (available in cans from Airstream store. Use applicator or disposable syringes to apply)

Rivet sealer:

Captain Tolley's Creeping Crack Cure

[lewster]

Originally Posted by TinTin

Yes, the lack of colour choice pretty much rules this stuff out. Some of the other 3M polyurethane products do come in gray.

I like Parbond myself, but have no personal data yet on UV breakdown. One thing I like about it, opened tubes remain usable for many months (perhaps years?), while opened caulking tubes of other items (Sikaflex, Adseal) have a very short storage life, even when carefully sealed.

Bob,

After using a tube of SikaFlex, I place a screw or nail in the tube opening and then freeze it. Lasts quite a bit longer that way.......just defrost and use!

I have also been using it for a bunch of years and it seems to hold up to UV very well on SOB roofing. I haven't had a call back on seam sealing where SikaFlex was used in about 8 years.

[TinTin]

Thanks for the tip, Lew. I've frozen paint rollers, hadn't thought of freezing opened sealant. Will give it a try!

[Aerowood]

I'll just throw this in, but I do not expect anyone else will use it due to cost. As many of you may or may not know is, I've stated many times that my Airstream DOES NOT LEAK this is do to the sealant I'm using and how I am using it
I'm using a two part polymer aircraft fuel tank sealant called PRC 1440 B, 1/2 or 2. It's and excellent sealant with superior UV resistance and adhesive qualities. It also has a shelf life. One of the perks I have at work is I can have it after the shelf life has expired as it is no longer legal to use on the aircraft, and we have to pay a hazmat disposal few to get rid of it. Everybody wins.

Now here's the hard part, I've opened up every seam on the trailer, cleaned, injected sealant and riveted it back together. I have also removed every window frame, removed the foam gasket and reinstalled wet using the PRC. I still have the awning rail to go but it will only take a couple of hours to do
While I was at it I installed sealing dome style nut plates on every penetration of the shell that a screw will attach a fixture. I also reduced the rivet spacing on the skin attachments to approximately one inch.
As a redundancy after I have finished with the task that I'm using the sealant for, I thin the rest to a paint like viscosity and then paint over the bucktails.

I'm really mystified as to way Airstream does not Fay surface seal as they are assembling the trailers on the line. The cost would be minor compared to the cost of doing the work again on the warranty line along with the dissatisfied customers.

[thumbelinadj]

I'm going to look for the PRC since I am at this perfect stage