Landships II

Dodo · Corporal

Painted fuseheads on British shells?

Gwyn Evans · Legend

Are you sure it's inert?! I know someone who makes a living going around museums inspecting ammunition that they think is inert and which, in fact, isn't...

Rectalgia · Legend

Not familiar with this field of collecting but I would have to agree with Gwyn in his concerns - an inert fuse on a (presumed) battlefield is fairly much an oxymoron. One that has (so far) failed to detonate is far more likely in the field and is a completely different thing. Yes, I have looked at (some of) Evo7125's videos and have (so far) been unable to discern any clues that might offer assurance (something to the contrary in fact). Yes, any nasty and sensitive bits should have denatured after all this time but that is not a lottery I would care to enter.

Dodo · Corporal

Oh, I'm pretty sure it's inert.. The shell it came off exploded over 90yrs ago... This is not off a dud shell, the fuse did its job.. The fuse heads are usually expelled more or less on contact once the shell explodes... This one, like most of the ones you see, has deformation around the thread where it screwed on to the shell... she's safe, just a lump of bronze now and a reminder of the horror of war... The ones on the pellet (see other photo) on the other hand, well they are live and are awaiting collection by the Belgian army..

So, what about the colour of the paint?....

Ironsides · Legend

Hi Dodo, I think what your looking at there is corrosion products not paint although it may give the appearance of such, the extent of the corrosion and depth of the layer would be down to its exposure to oxygen and the immediate ground conditions, many copper alloy items can remain remarkably untouched even after centurys given the right conditions...

I�would say it was typical for brass...

leaving the layer will not do it any harm and will actually help preserve it, removing it may since you would end up removing the original surface layer�of the item (effectively the top layer of brass has already�been converted to oxides) and any details preserved in it....

Cheers wink

�

-- Edited by Ironsides on Saturday 7th of January 2012 11:29:36 AM

Rectalgia · Legend

Thanks for the clarification Dodo, and the excellent photograph. Yes, that does look like the natural bronze patina to me - and it extends to the screw threads as well, which seems to clinch the matter. If fuses are painted it would be very poor practice to coat the threads as well. I think you should find a close match for that colour in collections of old bronze objects (I'm thinking coins in particular) though there will great variation.

Here are a few "coppers" I have laying about - while none of these have been shallow-buried in moist clay for 100 years and while they may not match closely the composition of your fuse (these would be mostly 97% copper 2.5% zinc and 0.5% tin) they might give some idea of what I'm talking about.

CharlieC · Legend

�

Just a thought...

Wouldn't the fuse bodies be made of free cutting brass since they are heavily machined parts. Normal brass can't be machined at high speeds because it tears rather than cuts. Free machining brass is about 61.5% Cu (nominal), 2.5% Pb (Lead)(minimum) and 35.4% Zinc(nominal). I don't know what the patina on free machining brass would look like but I'd guess it wouldn't be like normal brass items.

Regards,

Charlie

-- Edited by CharlieC on Sunday 8th of January 2012 01:05:48 PM

Rectalgia · Legend

Much the same patina as other brass/bronze alloys I believe Charlie.

"Introduction

This paper is intended as a brief primer on Free-Cutting Brass, UNS C36000. Free-Cutting Brass, which many people know by it's traditional name, CDA Alloy 360, is the most important commercial copper alloy, surpassing all but copper itself in terms of annual consumption.

...

Corrosion Resistance

When exposed to the atmosphere, brass tends to form a protective tarnish film that impedes corrosion beyond a few micrometers into the metal surface. The tarnish will deepen in color from bronze to dark brown, and may eventually take on the green color of a patina in some environments. The important point is that brass's corrosion rate in normal atmospheric conditions is low and self-limiting, and the corrosion products that do form are not objectionable."

http://www.copper.org/applications/rodbar/alloy360/free_cutting.html

P.S. A comprehensive treatment of "metal colouring" including patinas:

http://wwww.archive.org/stream/metalcolouringa00hiorgoog#page/n6/mode/2up

-- Edited by Rectalgia on Sunday 8th of January 2012 05:01:39 PM