I'm wondering what the best way to seal my new windshield is. The windshield only comes with felt and sealant is optional. I've heard of people using prestite sealing tape or a silicone to do the sealing. Those of you who have replaced a windshield in your Cessna, what do you recommend?

robw56 wrote:I'm wondering what the best way to seal my new windshield is. The windshield only comes with felt and sealant is optional. I've heard of people using prestite sealing tape or a silicone to do the sealing. Those of you who have replaced a windshield in your Cessna, what do you recommend?

I use 3M Strip Caulk on the parts that fit in the groove, and once the windshield is in then use masking tape around the perimeter and clear silicone. Run your finger over the silicone then remove the tape for a nice clean edge.

Try to cut the felt so the edge stays inside the groove. (makes the silicone easier to do).

You definitely don't want to use silicone as its the wrong application. I wouldnt put the sealant in the track, just use the felt. As suggested, install the windscreen, then mask both sides of the edge with tape (fineline is better than masking.) Apply and pull the tape.

This is a good product to use: http://www.aircraftspruce.com/pages/cs/ ... ac236b.php

bigrenna wrote:You definitely don't want to use silicone as its the wrong application. I wouldnt put the sealant in the track, just use the felt. As suggested, install the windscreen, then mask both sides of the edge with tape (fineline is better than masking.) Apply and pull the tape.

This is a good product to use: http://www.aircraftspruce.com/pages/cs/ ... ac236b.php

I saw this which looks very similar but appears to be specifically for windshields and canopies. http://www.aircraftspruce.com/catalog/a ... kkey=16359

When you say both sides of the edge, do you mean you applied it to both sides (front and rear edge) of the lower retainer strap?

robw56 wrote:

bigrenna wrote:You definitely don't want to use silicone as its the wrong application. I wouldnt put the sealant in the track, just use the felt. As suggested, install the windscreen, then mask both sides of the edge with tape (fineline is better than masking.) Apply and pull the tape.

When you say both sides of the edge, do you mean you applied it to both sides (front and rear edge) of the lower retainer strap?

Mask both edges of the seam that you are going to seal. Then tool the sealant with your fingertip to get a smooth, even radius. Depending on what your sealant type is, spit on your fingertip, or dip your finger in a safe solvent when you have to interrupt and resume tooling, to help keep it smooth. (Acetone works well with silicone, e.g.) Then carefully pull the tape to yield a really clean, smooth result. Try pulling the tape at a low angle, high angle, diagonal angle etc and you'll see pretty fast what gives the best result.

I've seen silicone used on many windshields, including mine that I replaced about this time last year. Wondering why it is not good for this application Bigrenna? I did it cause thats what the IA I was working with told me to do…as in everything, sure pays to do some research before hand

Really enjoying watching the progress on your build, great job!!!

Silicon won't take paint, that's one big problem, additionally it's very difficult to remove, should removal become necessary.

There's a PPG product, milspec something-or-another, that's 2 part. I think they sometimes call it pro seal. It's dark grey when mixed. It's used a lot in pressurized aircraft. Anyway, its the stuff for windshields.

Hearsay is that the clear silicone will eventually cause crazing close by.

Skalywag wrote:I've seen silicone used on many windshields, including mine that I replaced about this time last year. Wondering why it is not good for this application Bigrenna? I did it cause thats what the IA I was working with told me to do…as in everything, sure pays to do some research before hand

Because silicone is 5 bucks and thats the cheap way to do things and it is the reason people use it on GA aircraft.

Proseal is the correct sealant whether you use 890 B1/2, 1432, 1425, 8802 (Bigrenna's Suggestion)….. You will never see silicone on a transport category aircraft and if you do it was done by a hack.

If Proseal is good enough for Gulfstream and Falcon windshields, then its good enough for mine.

Proseal is also what we use in the military.

Watch your mix, too hot and it's brittle, too cold and it never cures. Look for Goldilocks

The two products above appear to be generics of Flamemaster and Proseal. As everyone has pointed out these are the accepted sealants to use when installing a windscreen. Having said that, neither of these have uv inhibitors worth a darn. If the doesn't get painted they dry out, shrink, crack, and are a pain to clean up and re seal. While silicone is not the correct sealant, quality polyurethane blends like Lexel or Sikaflex will go on clear, stay that way, and judging by the windows in my cub (6 year old lexel in AZ sun) will retain flexibility, long after the once a year Proseal cracks out of my work planes...

As often proven in experimental aircraft, what's accepted methods on certified, may not always be what's superior in performance.

Take care, Rob.

BTW, neither of the products I posted paints well, but IMHO they stay clear so well that correctly applied in a windscreen application they look better than painted sealant.

bigrenna wrote:You definitely don't want to use silicone as its the wrong application. I wouldnt put the sealant in the track, just use the felt. As suggested, install the windscreen, then mask both sides of the edge with tape (fineline is better than masking.) Apply and pull the tape.

This is a good product to use: http://www.aircraftspruce.com/pages/cs/ ... ac236b.php

The reason for the strip caulk in the groove is it helps keep water out better than just felt. When you change a windshield things come apart easy.
Clean the channel with Naptha it dissolves the caulk easily.
Also Naptha works on silicone just let it soak.

The felt by itself seems to "wear out" also. after a few years of heavy use there isn't much left of it along the bottom edge of the windshield.

B1/2 is stronger and lasts longer than silicone, also harder to remove.
I have seen cracks on Cessna's from using it though ( I have also seen some that do just fine with it too), it doesn't seem to flex enough for my taste.
Silicone is very flexible.

Rob wrote:polyurethane blends like Lexel or Sikaflex will go on clear, stay that way, and judging by the windows in my cub (6 year old lexel in AZ sun) .

Going to have to try them!

SixTwoLeemer wrote:

Skalywag wrote:I've seen silicone used on many windshields, including mine that I replaced about this time last year. Wondering why it is not good for this application Bigrenna? I did it cause thats what the IA I was working with told me to do…as in everything, sure pays to do some research before hand

Because silicone is 5 bucks and thats the cheap way to do things and it is the reason people use it on GA aircraft.

Proseal is the correct sealant whether you use 890 B1/2, 1432, 1425, 8802 (Bigrenna's Suggestion)….. You will never see silicone on a transport category aircraft and if you do it was done by a hack.

If Proseal is good enough for Gulfstream and Falcon windshields, then its good enough for mine.

Hack????

Ha ha.

I agree on the bigger planes with you Pro Seal!
But on cessnas the flex in the airframe will cause you difficulties.
Did you put in a v-brace in the 205 yet?

TangoFox wrote:Hack????

Ha ha.

I agree on the bigger planes with you Pro Seal!
But on cessnas the flex in the airframe will cause you difficulties.
Did you put in a v-brace in the 205 yet?

No V-brace yet but I do want to do the one-piece windshield and the other windows as well. The plane is currently in Twin Falls getting a radio stack put in and since I'm not rich, the windows will be on next years list.

When I do the windshield I may try another material in the channels because of the flex you speak of. Others have said the same thing… lots of flex! I will positively use 1425 for the rain seal on all windows, its the bomb. Been using it for 20 years on the G's.

When I find the mechanic that installed the windows on my last plane with RTV, he's getting a free haircut. It was a disaster cleaning up. Doesn't seem like it was done in Green River tho

Take care

SixTwoLeemer wrote:

TangoFox wrote:Hack????

Ha ha.

I agree on the bigger planes with you Pro Seal!
But on cessnas the flex in the airframe will cause you difficulties.
Did you put in a v-brace in the 205 yet?

No V-brace yet but I do want to do the one-piece windshield and the other windows as well. The plane is currently in Twin Falls getting a radio stack put in and since I'm not rich, the windows will be on next years list.

When I do the windshield I may try another material in the channels because of the flex you speak of. Others have said the same thing… lots of flex! I will positively use 1425 for the rain seal on all windows, its the bomb. Been using it for 20 years on the G's.

When I find the mechanic that installed the windows on my last plane with RTV, he's getting a free haircut. It was a disaster cleaning up. Doesn't seem like it was done in Green River tho

Take care

Do the V brace when the windshield is out. The bolts that attach to the wing root are a pain with the windshield in place!

Hey guys,

I’m resurrecting this thread because, for the life of me, I can’t remember how we applied the pro seal on my previous airplane. This summer while in Alaska’s I learned that my front and rear windows leak like crazy. So I bought the pro seal 890 in the tube with the mixing rod. I remember we mixed it with a drill last time, but I can’t remember what we used to apply it. No nozzle came with it like you see with some of the 3M stuff.

So can someone walk me through it? I thought for sure there would be a YouTube video out there, but I didn’t find one.

Thanks!

My turn to renew this thread.

Changing the windscreens on the 108. The last "mechanic" who was one of the lead instructors at a major private aircraft school used epoxy. I can't even begin to tell you the hassle that has caused to install and seal the windscreens. After 2 weeks of heat, wipe and they heat and use a solvent we are clean again, all but the very bottom of the track in the bottom screen retainer, I have not figured out how to get that squeaky clean. The rest is with out epoxy now.

I read this tread and I am not wanting to put something in that will be a bugger to clean up again if I have to do this again in the future.

It sounds like proseal is what larger ac use, however, will it hold up in smaller planes? Will the Silkaflex or Lexel come off? I can make a foam backer rod to go in the bottom of the channel on the retainer at the bottom of the shield, that will make the bottom of the screen have a softer material to sit against.

What do you all think.

I will say I NEVER want to do what I just did again EVER.

As previously stated - mask off the window so you have 1/8" around the circumference. Use ProSeal A2 or Flamemaster (less expensive) A2 and have at it. Don't use silicon!!!!!!