Halo Dimensions?

[Dinkydick]

Ok this question is for all the long time saltwater searchers.

Has anyone kept records or have good information on the sizes of
detectable halos surrounding ferrous metals.

Example - Suppose that a piece of ferrous metal is buried in beach sand
for along time. A rusty halo of sand starts to form around the object. Over
time this halo begins to enlarge as time passes. A person with a metal
detector can detect this halo and the object as they both contain ferrous metal.

Questions - How large do these halos become relative to the size of the object
over time? And are the halos still detectable once the object has been removed?

Has anyone detected balast rock from shipwreck sites? Was there a metalic halo
around the rock?

Thanks for any help

Dinkydick

 

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[DaChief]

Hey Dinky,

I can't speak to the ballast question but I can speak to the iron issue. I use a Pulse Induction Machine and I find iron on a regular basis when in dry sand. I cannot tell you of the age of the iron as I have not found a relic that could be dated but I have found many pieces of iron with the halo in place. For example I dug an iron rod from the dry sand on my last outing that was at about 15 inches. I know the depth was accurate due to the face that I struck it on the push down to retrieve it. The rod was thick, about 2 inches and about 9 inches long. It appeared to have been in place for some time. The halo had bled into the sand about 1 1/2 inches around its sides and ends. I pulled it from the sand leaving that halo in place and rechecked the hole, (not for the halo but for any targets that may be deeper). I didn't get a signal. I believe the pulse would have picked it up had the halo made one.

I would think that as a piece of iron degrades longer and longer, that eventually larger particles start falling off of it that would add more and more consitancy to the halo. It could in my opinion eventuall deposit enough matter into the halo to return a signal back to the coil.

When relic hunting with a VLF machine, I have found silver coins that have been in place for over 150 years. The halo effect there clearly aided in finding the coins. Rechecking those holes did not result in another signal either from the halo which is not visible to the naked eye on them. I know iron gives off a much larger halo due to the fact that it degrades faster. I have dug huge iron pieces in farm fields that had a tremedous halos of rust around them and once I have gotten those iron pieces out I have checked again behind them with no signal again. Not even a null from the iron mask.

Just my observations. Hope this may have helped add some information to your query.

DaChief

 

[Dinkydick]

Da Chief

Thanks for your help in my quest for information.

Dinkydick