Should all exhausts be just rusty?

[fingers]

I'm just building a Miniart Valentine and have reached the exhaust construction stage now I was, as usual, about to paint the exhaust a rusty brown prior to attachment and I thought hang on surely these exhausts would be treated/painted and wouldn't be fitted as raw steel

.

Does anyone know what was done?

It opens a lot of options for paint finish on the exhausts what with new steel against old and rusted, flaking paint, burnt paint, in what patterns and all the degrees in between.

[Test Graham]

They weren't actually rusty, this is a modelling "thing". They would be burnished steel. I tend to use a suitable metal paint and then dry brush streaks of other colours, but other modellers have their own approaches.

[bobgpw]

Hi fingers,

I can't agree with Graham as I would think it depends on the vehicle powerplant. My own experience is of the Ford GPW (aka Willys MB) as I own one. The exhaust is mild steel, untreated with the exception of being sprayed olive drab when fitted to the chassis.

Having re-fitted the exhaust, the heat from the very small 2.2 litre engine quickly burns the paint from the manifold and turns it a red-brown colour. Further down stream, the paint eventually weathers to a red brown, which coupled with continuous exposure to the elements allows rust to form. The system also deteriorates from within as water in the exhaust gas collects in the silencer.

For larger vehicles, especially tanks, I would suspect that the exhaust manifolds may be stainless steel as the temperatures generated by these engines could exceed that found in softskins. The rest of the exhaust such as the silencer would probably be mild steel and would discolour and eventually rust.

As for the Valentine, the photos I found on t'net show that on a MkVI, where the exhaust exits the engine bay and joins the silencer, there is a cast iron elbow. I'd think that any of these parts could easily discolour and experience paint flaking after prolonged use/exposure. That said, knowing us Brits, we will have made the whole exhaust from stainless steel.........

Hope that helps,

Bob

[Test Graham]

Sorry Bob, fingers: I saw the WW2 heading and assumed it was my usual aircraft subject field.

[Tiger Ausf.E]

Hope you do not mind me dropping in my pennies worth!

I would think that the rust affect would take time to come in, the tanks exhausts would not go rusty on day one, and I think in some climates the rust would take longer to come through than in others. So depending on how long you want to depict your tank has been in the field would dictate how rusty the exhausts would be.

[Kiwidave4]

The major components of older vehicle exhausts were mild steel and cast iron. Both these metals will develop surface rust very quickly when exposed to oxygen and water. High temp paints are fairly recent, and even they dont last long on the primary section of an exhaust. Quality motorcars once used vitreous enamel on the manifolds to provide a corrosion resistant finish, but I dont know if that was ever used on tank engines. Given the anticipated service life of a weapon of war I guess not!

If you fit a new mild steel exhaust to an engine, run the engine at full operating temperature, and then leave the engine to stand outdoors for 24 hours there will be signs of corrosion appearing, especially at the primary end.

And cast iron can literally rust as you watch it.

Post-war AFV such as the Centurion and Saladin had a spaced sheet metal cover over the silencer. In-service pictures clearly show corrosion on this as a result of the heat from the silencer burning the paint off the cover. It is reasonable to assume the silencer would be at least as rusty.

I am not a great fan of weathering but exhaust pipes are one area where a bit of rust is appropriate.

Regards Dave

[fingers]

Thanks for the replies guys.

It seems to me that it would be possible to justify considerable variation in exhaust condition dependant on age (new clean against rusty), paint applied at factory to prevent premature oxidation (red oxide?), pattern of heat effect and field applied camo variants.

Unfortunately exactly how they looked is probably going to be a victim of the b/w photography of the era.

I wonder what the Axis powers did?

[Tiger Ausf.E]

Hi Fingers,

I put these up elsewhere on the site, but you may have missed them. These pictures show the actual exausts of a Tiger that is up and running. You can see how the paint and metal is being affected by the heat.

I hope you find these helpful.