Preservation of cast iron recovered from salt water

[Wgreen]

Hi all just thought I would tell u a way in which cast iron objects recovered from the sea can be preserved ,lots of objects made from cast iron are recovered from the sea each year(cannon balls) many of which unfortunately are doomed to slowly break apart and turn to rusty dust .when cast iron is recovered from the sea it has over many years of attack from the salt water lost some of its carbon content slowly turning it to graphite and at the same time has absorbed sea water and chemicals which once exposed to air readily turn to corrosive elements which break the surface apart allowing air to get even deeper into the object making complete destruction an eventuality .what to do ? The best treatment I have found is called electrolysis and it is a simple solution u will need a AC/DC converter of no more then 4v strip each end of the wire mix up a small glass of salt water and place each end in the water with a gap in between the one that bubbles is the one u need in the end to attach to your cast iron object ,then u will need some costic soda ( drain cleaner) and a plastic tub large enough to hold your object for treatment with a space around of at least 6 " now connect your DC converter to two metal objects stainless steel is best one on each wire one must be big enough to hold your cast iron object and arrange them in your tub if u can put something under the item for treatment to hold it just of the bottom of the tub u will get better flow ,placing the two stainless steel items opposite each other is best ,once set up place your cast iron object on top of the stainless steel which gave of the bubbles now get your costic soda remember gloves and eye protection this stuff is nasty I use a small cup filled up to every 15 Lt of water and fill up your tub to just over the level of the object to be treated once u are set up and happy turn on the power u should see bubbles coming from both wires costic soda is very conductive but u should slowly see bubbles start to come out of the cast iron may take a few minutes ,now just leave to bubble away depending on the size and weight depends on how long and how many time u must change the water in the tub I've found a 32 lb cannon ball take two weeks with at least two changes of water ,after which a quick ten minute boil in water to drive of moisture from inside once removed allow to cool and dry for a few days before spraying with a sealer it's like most things it seems hard but I can assure u it is not and once treated u will have a artifact to treasure that won't crumble to dust, hope someone finds it useful I did

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[mach1bang]

Hi Wgreen,
Thanks for posting.I thought this process should take at least 6 months,not 2 weeks though.
How long have items lasted after treatment so far?
Cheers Tim.

 

[Wgreen]

Hi Tim I started doing this about a year ago when found a very informative site wrote by a professor of archeology his team recover historic artifacts from shipwrecks mainly large cannon and such and the item he had used to explain the process was a large cannon weighing 3/4 of a ton so roughly 1500 lb this took a year to remove all the concretion and salts from within so something only 32lb should take 8 days but that is only a guide roughly 4lb a day but I allways go over to make sure.i have found lots of cannon balls hundreds even and had to watch nearly all of them break up but since starting this process I have had none the first one I did was a small c ball a bit larger than a baseball I've had lots they are bad for breaking up treated it a year ago and it is still perfect,I have noticed a few things since starting this when u first but an item in the treatment the water/ costic mix will become quite scummy on the surface and lots of debris will fall of the item to the bottom when this water is changed the next time u will start to see white (what looks like fluff) coming out of the object I'm not an expert but I assume this to be the salt being pushed out by the bubbles from my experience the item is well on it way to being done as I said I started out about a year ago and the days of loads of cannon balls have gone but since I started I have treated a 6 lb ,12 lb ,18 lb cannon balls a cast iron 6lb ww2 projectile a 1.5 lb cast practice cow gun proj quite a few ww2 2 lb steel proj but it stops the dreaded sweating were salty water drips from items removed from the sea, a large piece of 10" rml which is a good two inches thick and at this moment a stunning 1870 6.3" 64 lb rml which I work out should take about 3 weeks. all of this is just my personal observations and I claim to be no expert but I also heard it take a long time up to a year and it does for a cannon weighing up to a ton and being so thick but a cannon ball is a lot smaller time will tell with my items but the difference between not doing this and doing it is amazing I more thing I forgot to add to the original thread is never when found let the item dry it will start to corrode immediately I place them in a plastic bag till home then in a bucket of water and costic mix untill I am ready to treat I will post some pics of thing I have treated, hope this is useful

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[Wgreen]

Hi Tim I started doing this about a year ago when found a very informative site wrote by a professor of archeology his team recover historic artifacts from shipwrecks mainly large cannon and such and the item he had used to explain the process was a large cannon weighing 3/4 of a ton so roughly 1500 lb this took a year to remove all the concretion and salts from within so something only 32lb should take 8 days but that is only a guide roughly 4lb a day but I allways go over to make sure.i have found lots of cannon balls hundreds even and had to watch nearly all of them break up but since starting this process I have had none the first one I did was a small c ball a bit larger than a baseball I've had lots they are bad for breaking up treated it a year ago and it is still perfect,I have noticed a few things since starting this when u first but an item in the treatment the water/ costic mix will become quite scummy on the surface and lots of debris will fall of the item to the bottom when this water is changed the next time u will start to see white (what looks like fluff) coming out of the object I'm not an expert but I assume this to be the salt being pushed out by the bubbles from my experience the item is well on it way to being done as I said I started out about a year ago and the days of loads of cannon balls have gone but since I started I have treated a 6 lb ,12 lb ,18 lb cannon balls a cast iron 6lb ww2 projectile a 1.5 lb cast practice cow gun proj quite a few ww2 2 lb steel proj but it stops the dreaded sweating were salty water drips from items removed from the sea, a large piece of 10" rml which is a good two inches thick and at this moment a stunning 1870 6.3" 64 lb rml which I work out should take about 3 weeks. all of this is just my personal observations and I claim to be no expert but I also heard it take a long time up to a year and it does for a cannon weighing up to a ton and being so thick but a cannon ball is a lot smaller time will tell with my items but the difference between not doing this and doing it is amazing I more thing I forgot to add to the original thread is never when found let the item dry it will start to corrode immediately I place them in a plastic bag till home then in a bucket of water and costic mix untill I am ready to treat I will post some pics of thing I have treated, hope this is useful

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The first one I ever treated still looking good after a year no cracks no dripping

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