Preservation of 1865 iron

[Bellifortis]

This 8cm lead-skirted prussian shell of the Prussian-Danish war of 1865 I feel very fortunate of having gotten at an auction, quite a while ago, but it is falling apart slowly even while you watch. The iron oxidises horribly fast. I tried to take explanatory pictures. It's similar to a mould invading the iron in patches. Sometimes even larger , black coloured scabs, peel off. What can be done to preserve this artefact ?

 

[highlandotter]

Look into the processes use by marine archaeologists to preserve objects removed from the sea. Good luck, the Otter.

 

[Slick]

What Otter said. As well, it looks like galvanic reaction might be playing a part in its disintegrating. If it was mine, I'd put it in a can of oil 'til I found a better process to stop it from degrading further. Maybe some sort of electro-emulsion.

 

[Bellifortis]

I have read into the specialist literature for many years now. The archaeologists in Denmark probably have the longest experience in trying to preserve iron objects removed from the sea (16th century cannon). They used to sell a nice small publication (which I have) at the "Toihuis Museum"(the old Arsenal) in Kopenhagen describing their work with the 16th century cannon over a few decades. Many different paths have been tried (even placing the iron in a fresh water stream for many months), but the degradation could only be stopped for a while. The problem with seawater recoveries is the salt. I do not have the financial facilities at my disposal that governments have. My object has not been recovered from the sea and I do not understand the chemical reactions that are taking place. Does anybody here know of a simple test one could make to get to the root of this chemical degradation. It for shure is a REDOX reaction. Only 40 year have passed between the Prussian-Danish War and the "German War Of Independence"(from Napoleonic occupation). Cannonballs and sperical shells from Napoleonic times (around 1800 ) never show this degradation. There has to be a difference in the type and working of the iron (pigiron ?) used in the 2 periods. Does anybody have any info ? A similar problem occurs with medieval crossbow-bolts. This iron falls apart in layers. The colour of the scabs that fall off is black, not brown.
Regards,
Bellifortis.

 

[BMG50]

Try and contact the V&A museum London about preservation or the Historic Portsmouth docks, they may know something about preserving iron contaminated with salt water.

 

[Bellifortis]

This shell was not found in seawater, so I do not know if salt is the source of the problem. By the way, I'm not a shell collector. This shell is the only one I ever bought, because it is so important historically. It is very,very seldom in warfare, that a munition wins a war. Most people in the world have been made to believe that the Atomic bomb won the 2. World War. But that is not the case. Incendiary bombs destroyed many more citys and the storages were overflowing in 1945 while production was at its height. For those who are interested I can recommend very much the extremely well researched work "Making Goop out of Lemons", which you find online. The above pictured Prussian shell won the Prussian-Danish war. Or better said, it's fuze. Up till that time all explosive (Black Powder) bursting shells had a time-fuze. All the danish shells, all spericals, were mostly fuzed with wooden time-fuzes. The prussian fuze "Zuendvorrichtung (aelt/C)" was the first mechanical impact fuze, just newly introduced in Prussia. Thus the prussian artillery was able to let their shells explode in the middle of the defenders at the "Dueppeler Schanzen", while the danish shells exploded before , behind or too high, with little effect. I attach a drawing of this first prussian fuze.
regards,
Bellifortis.

 

[Depotman]

Try contacting The Royal Armouries, Fort Nelson, Portsmouth. They have huge experience in preserving iron guns. Depotman

 

[pzgr40]

You cannot stop the rust. This projectile is not made from steel, but iron with a lot of carbon(inclusions), called "pig iron". In facto it is like an iron-carbon sponge. That was no problem for the black powder propelling charge guns of those days, as pressures were relatively low.
We used to find dutch 5cm practice shells near where I live from the 1900's. After drying them, we found out they could be crushed with one hand only as the only thing that was left was a carbon skeleton, all the iron was oxidated away.
I'm sorry to say, but I'm afraid you'll have to accept it will slowly degrade.
The only thing that seemed to slow down the falling apart somehow -as a friend of mine discovered - was to cook it in linseed oil and soak it some more in there for some weeks. I suppose it had to do with locking out oxygen.

Regards, DJH

 

[25thapril]

If locking out oxygen is the way to stop it flaking away could you dip it in wax ? I have seen on YouTube somewhere a bloke preserving cannonballs and 75mm AP rounds by dipping them in wax . Just a thought
regards Daryl

 

[Rockteer]

Hi, I clean up a lot of crap being into aircraft recovery and WW2 in general including a number of steel and iron items out of the sea. It can be preserved – don't panic, if it were me, I would use evaporust untill the rust is gone, Matt laquer over the top (when dry) do not was after dip in water as it will begin to rust again, any surplus evaporust acts as a corrosion inhibitor and the laquer is quite happy sitting on top. After all this then lightly oil over the laquer, the idea being if the laquer (which locks out the oxygen) gets scratched the oil will act as a back up and will naturally run into any inperfections from the laquer, if it has only just been recovered from the sea, then it may need cleaning several times over but it will settle down, you just need to keep an eye on it and if and when it begins to show signs of rusting again (rust speckles) repeat the process. No need to strip off the old laquer as evaporust will remove the rust where it has broken through the surface coating and unaffect the remaining laquer, it can then be recoated and eventually it will stop completely. I have treated a number of items out of the sea and find this works. The great thing about this method above is that no abbrasive wire brushes are needed.