Brief Description: Firewall completion & sealing it off.
I was not sure what to use to seal off the firewall holes and rivets heads. So I selected an High Temp silicone to seal off each rivet heads. Although, fire exceed 700 F , the silicone being locked between the rivet head and the SS sheet, it will hold long enough in case of a fire as I imagine to be on the ground as fast as possible in case such event happens. But for holes, I used an intumescent 3M fire Barrier that will, in my opinion block off all holes better than the high temp silicone. The 3M fire Barrier is rated as 4 hours resistance to fire, more than required. But because it's intumescent, I would not use it between parts but for holes it will work great.The third part of fire protection will be to add a ceramic wool that will be held in place by a thin aliuminium sheet on the cockpit side; ceramic paper used by many does resist to high temperature but does not provide a temperature drop (cold side) as good as a 1" wool will. All this add a bit of weight but a ton of fire protection. Finally all these sealing compound will help block CO2 ingression as a bonus which is not to be neglected.
Sealing compounds
Rivet head red beside a hole with the grey 3M compound