Window Sealant

[Bcone1381]

What is the EAB Industry Best Practice for sealing windows? I am hoping to seal up the side window and have done some experimenting. But before I go and try it I bet there is a best practice being used I dont know about. The second photo shows an example....it's the Patrols rear window channel. When it rains water will enter.

One concern or unknown factor/question.....will the window be removable after I apply the sealant. Should it be?
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I've been playing around with 3M Strip Caulk. This stuff is kind of like tar, but it does not set up. It stays sticky and pliable. Its like chewing gum, but stickier. I experimented with a piece of angle. I got a nice result by applying painters tape to both sides, then pushing the caulk into the corner, removed excess using a 1/4" wood dowel, then removing the painters tape. That little ball of caulk sat in the shop all week and was still like new today. I'm not sure how to smooth it out, and don't know any trade secrets on how to apply it. I'm not experienced or skilled with caulk of any kind. need help.

I think if this was used the it a builder could dig it out to remove the window, but Scratches during digging would be a significant risk.

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[alaskabearhawk]

FWIW, I used SikaFlex 221 in aluminum gray for all my windows, skylight and will use it for my windshield. It's very easy to use.

http://www.mykitlog.com/users/display_log.php?user=yeeeha&project=527&category=3583&log=307093&row=5

https://skygeek.com/sikaflex-0221243-221-non-bag-polyurethane-sealant-black-10-3-oz.html

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[noema]

I tried different sealants and found the 221 great. It's fairly cheap and decently easy to work with. I usually tape the area left and right, apply it, scrape off excess with a custom shaped plastic spatula tool, remove tape, then shape rough areas with my finger and soap water, then clean up any smears and discontinuity with plenty of q-tips and ipa. Typically hardens in a couple of hours when its warm. Used it down to 10degC with no problem and so far hasnt caused any grazing or cracking on acrylic and polycarbonat (even though sikaflex has other supposedly more compatible versions for PC and acrylic)

[Paul Johnston]

Brooks it’s been my experience that any type of goo will turn on you sooner or later, I wrapped the edge with felt that’s intended for covering pool tables then cut off the excess with a single sided razor blade. Just did top of windsheald and skylight so it won’t drip when flying in rain. But the goo can be cleaned from plexiglass acrylic if you use taluline,and look like new. Don’t use toluline on polycarbonate- it will melt

[Utah-Jay]

I used Butyl Tape to seal my rear windows. I will likely do the same for my windshield

[Fatiger53]

Based more on street rod building (as a first time Bearhawk builder) I like the non hardening sea
lers like you used or in a tube applicator from 3M found at auto body supply houses. Seems like every other product that sets up hard leaks sooner or later and doesn't handle vibration well

[Steve W]

I’ve used Silpruf SCS2000 on two aircraft I built, the Patrol and a Glastar. It only has a one year shelf life. It has adhesive properties but remains flexible after it cures. It doesn’t shrink either. All the Glastar windows, windshield included, are retained in a lip or sill with that stuff. I used it on the windshield and rear windows of the Patrol. My rear windows are recessed in a wood frame. I didn’t use any screws through the acrylic on the windshield. All the perimeter of the shield is sandwiched between the outside formers and inside retainer strips. I like it but is hard to get north of the border.
Steve P203

[stinger]

Over thinking , the rear window needs very little sealant, just install your blue tape to give you a good line and use auto gasket maker along the outside up the trailing edge and along the bottom . Window will be easy to remove if you ever needed .Never had a leak . Stinger

[Bcone1381]

Over thinking ........ Stinger

Thats an industry best standard advice....don't overthink it Brooksie!

[Bcone1381]

I ended up using my 3m strip caulk. I taped both sides of the gap, applied the strip caulk with my fingers and sheared off excess with a pop sickle stick. I removed the tape and have a neat appealing seal. This stuff cleans up easily with a little Naphtha on a paper towel. Easy to control, shape, and clean up.
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[Ryan Koeneke]

Hey Brooks, thanks for posting the trial and error process of making strip caulk look good. I was on method 4 when I went to search for answers and found your method which works great.

Do you have any long term review of strip caulk on exterior windows? I'm going to use it on my windshield-boot cowl connection since that lives under a fairing. But I'm worried that, since it never sets up, junk will get stuck in it and using it on door windows it might end up getting smudged around with fingers gripping right on the window frame-window interface.

[Bcone1381]

Here is my long term (1 year) review.

• Strip Caulk is thinned with 100LL.
• If "Junk gets stuck to it" I do not notice it.
• The application for the side windows and the windshield are working out great.
• SMUDGING
  • I've had no smudging issues.
  • I don t feel like I have to be careful of it.
  • It'll be easy to clean and restore if it gets smudged.
  • Beware, "Intentional smudging" will smudge it, but an inadvertent brush will not.
• SKY LIGHT
  • 3% of the sealant has lifted off the front lexan/fitting seam.
  • Suction created by lift seems to effect MY application here.
  • Lets call if Builder Install Error.
  • Laziness mandates that I go fly on nice days and do somethings else on other days so I've left it so far.
  • Maybe I did not press it into the crevice up there well enough?
  • I'll redo it during the condition inspection. (January)

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