Roof sealant ?

[sphanna]

I think I screwed up. I tried to post a thread to ask for info on what to use to seal the top to keep water from seeping on the headliner. I have used black silicone in the past but I would like to find a better solution this time. I just repainted my Fordor and tried to post the new thread it did not come up but it did go to my album. Why, I do not know. ????

Is there a recommended product to use for this sealant?

[700rpm]

What is your top material?

[P.S.]

3M 5200 black. It takes about a week to "dry", but will outlast the top material itself.

[Craig Lewis]

1) Silicone sealer and bare metal is an incompatible combination. As soon as moisture enters the picture, the silicone will promote rust.
I would use a liquid butyl product under the roof strip so the nails draw the butyl through the metal and totally encapsulate the seal. Butyl is a flexible, petroleum based sticky product that exudes a slight oily film into surrounding metal (effectively preventing corrosion) and reflowing slightly on warm days. A denser version of it was called "dum dum" or "tape kit" and was used to adhere most automotive glass though the sixties & early 70's.
1960's vehicle pinchwelds (the metal body flange around a windshield) didn't suffer the severe rust we see around windshields today because the exuding oils from the butyl seemed to help protect the paint gauges inflicted by careless glass installers.

2) In my glass business we use 2 versions of butyl distributed by a large company called C.R. Laurence.
Butyl Rubber Sealant #777 is free flowing and I think would be ideal.
Windshield sealant #7711 flows slightly thicker and skins over...drying semi-rigid after a few days but is reworkable if wiped with mineral spirits or mild solvent. This is ideal for running a thin lick around a rubber seal or window that might leak (instead of silicone) and can be reduced to a fine edge with a solvent rag.

3) Getting back to silicone...I need to stray off Model A's for a minute but pictured below are typical examples of the damage inflicted by nearly every glass shop across the nation...on your everyday drivers. The bare metal left behind by their sawzalls and reciprocating razor knives turns to rust in short order but is hidden by the trim molding so they "get away with it" every time.

4) The final 2 pics shows a mini van as I found it with silicone smeared around the molding. Notice how much more severe the rust is (it had holes rusted right through)....this is typically what I uncover each & every time there's silicone near bare metal.

Silicone = good for bathtubs & boobs.

[Al Bass]

Originally Posted by P.S.

3M 5200 black. It takes about a week to "dry", but will outlast the top material itself.

I second the 3M 5200. I've used it to seal windshields and rear windows on older cars and the top material on on my 31 Tudor.

[sphanna]

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Thanks, Guys, all of you.. I will research these suggestions. I appreciate knowing where to start.

[Craig Lewis]

I did a search and see 3m 5200 is a urethane.
A bead of urethane has been used to hold windshields in cars for the past 30+ yrs. It fills gaps, adheres to smooth, carefully prepared surfaces & cures to a rubber tire consistancy.
I can see it being used to seal top moldings successfully, although anyone who's never handled the product is in for a surprise in the cleanup department as it's relatively fast curing, very messy and tends to "get away" from you.
Assuming we're taking advantage of a sunny day to smooth out the roof material wrinkles, I'd say the urethene will begin setting up in 10 minutes ...that's the workable stage...after this it still moves around except with each move you're permanently breaking the bond and increasing the risk of water seepage. I've worked with alot of urethane and not sure I'd want to be rushed like this on something as finicky as a top, although if you were an expert it would be one heck of a strong bond providing one could get it all nailed down in time!
My feelings are that I would still prefer the selfhealing, reflowable properties of a butyl product under my roof moldings as it's far less permanent and infinately reworkable over extended time periods.
Many of you folks have more experience with Model A tops than me... I remain open to all feedback.

[P.S.]

Originally Posted by Craig Lewis

... anyone who's never handled the product is in for a surprise in the cleanup department as it's relatively fast curing, very messy and tends to "get away" from you.
Assuming we're taking advantage of a sunny day to smooth out the roof material wrinkles, I'd say the urethene will begin setting up in 10 minutes ....

Apparently, you have never used 3M 5200...

It takes a week to 10 days to set up. You can literally work it for 2 days without the fears you expressed. The product gives you a tight bond no matter what.

[sphanna]

I failed to mention that my roof is installed and has been for years. The metal strip is nailed down. I just want to keep water from seeping in under the strip and through the nail holes, etc. I thought that running a bead against the inside of the strip will preclude problems. It did leak in a heavy rain storm a little bit about a year ago. At the time I used silicone which stopped it, but now I see that silicone was a poor choice.

[P.S.]

You could certainly run a bead of 5200 around the seams to help keep the water out.

It would be best to first remove the silicone, then apply the 5200. I ran a bead of 5200 around the top material on my Tudor along the front, sides and double along the back. No leaks.

The trick is to press the sealant into the space between the top material and the strips, then wipe away any excess so it doesn't look crummy. I used a spreader to open the gap between the material and the strips then let excess squeeze out after moving the spacer.

[sphanna]

Sounds good P.S. Thanks. I did remove all the silicone in order to paint.

[wrndln]

It appears that 3M 5200 would be a good sealant as it seems like it can be "worked" for a while. I need to install the two piece metal strips on the header and rear part of my 28 special coupe. I currently don't have 5200 sealant. Most sealants are a mess to use. For someone that has used it before, how difficult is it to remove the excess that squeezes out and what solvent do you need to use.
Rusty Nelson