Firewall Insulation Glue

[Randy Hooper]

In my uninsulated RV-8, my feet sometimes get uncomfortable hot. I am going to use Theomozite with foil on both sides for insulation material. I researched glues and found 3M 1300 with heat range of -30F to 300F to be my choice for attachment. Does anyone have experience with a better glue in this application?

[Jeff A]

Randy-

I'm not aware of any better option than 1300 (or 1300L which is sprayable). We use it extensively on all interior components on our company airplane. If you follow 3M's application instructions, you can't go wrong.

[Randy Hooper]

Jeff, 1300L is pretty thick as it comes from the can. Have you experience spraying it? What do you use for thinning? What is used for spray equipment?
The spray application would make a much nicer job than brushing.
Thanks.

[Lars]

After reading this thread in its entirety, I ordered some 1/2" thick refractory insulation from McMaster-Carr as described in post #64, along with some 5 mil aluminum foil. I plan to wrap the insulation in the foil, then drill some holes in the firewall stiffeners and use safety wire to retain the insulation panels, as described in post #73. As awful as a fire sounds, I figure that minimizing smoke and fumes in the cabin will improve my survival odds at least slightly.

[Jeff A]

Randy-

I haven't needed to spray 1300L for quite some time. Normally, I am applying only a small amount....maybe 6" x 6" for small interior panels or repairs. The few times I have sprayed, I used a cheepo touch-up spray gun (Ingersoll-Rand, I think) that I bought from Grainger or Northern Tool. If the 1300L is stirred properly, thinning shouldn't be necessary. Although, I'm sure a VERY small amount of MEK or Naptha would take care of the job. Since the areas between the firewall stiffeners are fairly small, you could probably get by with brushing the adhesive on without a problem. Spraying can be pretty messy no matter how careful you are.

[hecilopter]

RTV red spread in a "W" pattern on the back of the foil covered insulation. Been OK for 700hrs so far.

[Larry Ocker]

Contact cemet works great.

[Jim Percy]

I used 3m 90 from an aerosol can. They call it "high strength" but I used it more because it has a higher temp rating than the other 3m contact cements. ~250 hours and no sign of separation.

[DanH]

A Thermozite insulation blanket was one of the first materials tested on the hot firewall rig. It is polyester fiber between aluminum foil sheets, and burns like a torch.

Below is a repeat from a previous thread. If ya'll keep slapping stupid things on the back sides of firewalls, soooner or later we're going to have a Darwin award winner right here in the RV community.

And BTW, 3M contact adhesive ignites in less than 20 seconds.
_______________________________

Sample was held in loose contact with the stainless "firewall" using two clamp strips at the vertical edges:



The sample was emitting heavy black smoke a few seconds after flipping the burner valve. It burst into flame in about 15 seconds. I dropped the Raytec and grabbed the camera. This was about 30 seconds into the test:



A few seconds later, from the "engine" side of the firewall:



The fibrous insulator between the aluminum foil sheets was rapidly consumed. The flames you see here were jetting out from between the foil sheets. The foil was mostly intact after the test, indicating a temperature at the insulation package less than 1100-1200 degrees F. The stainless temperature is around 1500-1700 F.

There is a very large difference between an appropriate firewall insulation and an FAR-compliant cabin wall insulation.

[flyboy1963]

I also am one of those interested in insulating my firewall.
As Dan says, 3M spray adhesive is best left for glueing the headliner in your car!
It melts, the insulation falls off, then ignites in 20 or 30 seconds with any heat at all.
Water-based contact cement seems to perform much better, with the caveat of possible corrosion of bare aluminum.