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Firewall finishes.

Posted By:
Denis Mexted
#1 Posted: 12/6/2010 18:53:49

Hello all,

A friend ask me yesterday what he should finish his stainless firewall in his RV in. I'm interested because I've got one for my DR-107 to do.

I recently saw a stainless C-180 firewall going in that in my opinion needed finishing. The firewall in my Cub has a Ceramic coating on it that after 13 years looks great. 

But what is this forum's thinking???

Dave Prizio
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
#2 Posted: 12/7/2010 11:26:58

I don't think that a stainless steel firewall needs any kind of finish. Bare stainless usually has a nice finished look to it. If it doesn't you can just clean it up and maybe polish it a bit.

With mild or chromoly steel you need some sort of rust preventative coating, but with stainless steel no such coating is required or usually desired. 

There are some ceramic coatings that can help retard to progress of heat through the firewall, but they are not required. If however, you have a structure behind the firewall that is flamable -- wood or composite -- that is another matter entirely, and no coating alone is sufficient to protect that.

Denis Mexted
#3 Posted: 12/7/2010 16:28:22

Thanks Dave,

The problem I had with the Cessna 180 stainless firewall was that it had rough gouge marks where it had been de-burred at any of the holes.  If the burr marks had of been polished out then yes it would have looked good. As it was it looked unfinished.

#4 Posted: 12/10/2010 02:50:32

Hi Denis,

Whatever coating you use on your firewall, it must not be combustible or support combustion.

That's why it is called a firewall.

The nearest heat resistant paint coating to a ceramic, vitreous enamel  is " Sperex " exhaust paint.

However, after it has dried it needs to be cured at exhaust temperatures for it to become inert to 1200 degrees.

Thus, unless the whole firewall is completely separated from the aircraft, curing it with a blowlamp is a no brainer.

Also, until Sperex is properly cured, it is easily dissolved with petrol( Gas ) and other solvents.

Sperex  also messes up very easily.

So unless something else is available, keep the firewall clean and keep the engine cowlings on.

A polished firewall will reflect heat and will keep everything behind it just that little bit cooler.