9/8/25 Report - Treasure Coast Mystery Object Find for ID and Cleaning. Factors Influencing Metal Detector Conductivity Readings.

Written by the TreasureGuide for the exclusive use of the Treasure Beaches Report.

Mystery Object Found on Treasure Coast by Vance D.

Vance D. sent the above photo along with the following message.

Not sure what it is I was wondering what I could soak this in to de-rust it to better identify it without destroying it if it's something important

Thanks Vance.

Of course it is impossible to tell what it is from a photo without any measurements or other information.  If there is nothing in a photo to suggest the size measurements would be helpful.

But from what I can see, the shape looks like a strap hinge (see below) to me, and maybe a bolt on top.

My preferred procedure would be to first soak it in distilled water to leech out the salts (do that with any suspected encrusted iron object) then mechanically remove as much of the surface rust as possible.  After getting a better feel for how solid the item is under the crust, perhaps try electrolysis or a rust remover.  

Here is a previous post on electrolysis. It provides a number of additional links.

Treasure Beaches Report: Pt. 2. (2020 and Beyond). : 7/5/25 Report - Electrolysis: Options and Use on Treasure Coast Beach Metal Detector Finds. Instructional Resources. 4th One More Time.

And here is a link to some posts on EOs.

The Treasure Beaches Report Direct From Florida's Treasure Coast.: 6/24/19 Report - Encrusted Objects (EOs), Clumps and Conglomerates and Their Contents.

Any reader guesses on the object or recommendations on cleaning?

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I recently mentioned in one post that metal detector conductivity numbers are not sufficient alone to identify the metallic composition of a buried target flawlessly.  An old test I conducted showed a very large range of numbers in response to a variety of gold targets.  In the past, I've posted a number of tests that I conducted to determine the metallic composition of differenti kinds of targets.  Today I wanted to look at a couple of those tests to show some of the factors that can affect a metal detector's conductivity number reading.

The first test that I'll mention involved large coins, including a gold American Eagle coin, a 1922 Peace dollar and a 1971 clad Kennedy half. The American Eagle coin is 91.67% gold, 3% silver, with the remainder being copper with a reeded edge. It is 1.287 inches (32.70 mm) in diameter, so in diameter the gold coin is a little smaller than the Peace dollar but bigger than the clad Kennedy half.

The Equinox 600 produced conductivity numbers mostly in the range of 32 -34 on the Kennedy Half, and 37 - 38 on the Peace dollar, which was consistent with the numbers produced by these coins in other tests. The American Eagle gold coin produced numbers that centered on 26 - 28. The conductivity numbers are more consistent when the detection depth when the depth was moderate.

When the coil was close enough to the coins, the conductivity numbers obtained on these three coins were different enough and consistent enough to reliably discriminate between the three coins used in the test. .

In that test with large round coins laying flat, the Equinox conductivity numbers very well reflected the conductivity of the metallic composition of the coins. Silver has a higher conductivity than copper by a small amount, and gold is lower than silver and gold and the conductivity numbers obtained in the experiment reflected that very well.

Here is the link for more detail. 

Treasure Beaches Report: Pt. 2. (2020 and Beyond). : 2/12/23 Report - Would You Correctly Identify A Buried Gold Coin Or MIss It? I Was Amazed by One Thing I Learned.

So it would appear that under certain circumstances the metallic composition of objects can be consistently identified by metal detector conductivity ratings.  However, there is more to the matter.

In another experiment I used Spanish reales of different sizes, and different shapes.  Although there could be differences in the amount of alloys in these coins, I assumed that they were pretty similar.

The Mexican half reale weighs less than half a gram and gave readings from 5  - 12, depending upon the sweep.

The second was test coin was a Postosi half reale from Jupiter, which was pretty round and weighed 0.8 grams.  It produced a steady conductivity number of 19.

The next reale reale weighed 2.7 grams.  It rang up consistently as 16 or 17.

Fourth at 4.7 grams was a Carlos and Juana two-reale.  Carlos and Juana reales are thinner and more round than most 1715 reales.  This one resulted in a very solid 20 on the Equinox.  Not too far off the Jupiter reale, which is also pretty found but much lighter.

And last is a four reale that weighs 13.8 grams.  It produced a solid 30.

So there you have it.  The conductivity numbers varied with size and shape, not just metallic composition.

Here is that link for additional details.

Treasure Beaches Report: Pt. 2. (2020 and Beyond). : 8/24/21 Report - Metal Detector Conductivity Readings for Spanish Reales. Mystery Item Identified.

Targets that are round and large and not too deep will produce numbers that are more consistent, but when targets are irregular in shape or deep enough to not give a strong signal, or very small or deep, the numbers are not so consistent.  The position of the item can also affect the reading.  Place a coin on edge and you'll see the reading vary depending upon the amount of surface area presented to the coil and direction of the sweep.

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Targets of very different shapes and alloys, such as various pieces of jewelry, will also cause greater variation in the numbers reduced.  Most objects are not purely one metal but will contain some alloys.  The exact composition will not always be known.  You'll also note some deviation in the numbers when the target is not well positioned under the coil on various sweeps.

To sum it up, there are circumstances when the conductivity numbers are pretty accurate, but there are also factors that will cause inconsistency, making the numbers less accurate and useful as indicators of the metallic composition of the target.

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Historically we are right at the peak of hurricane season, but there is nothing on the hurricane map.  

Source: SurfGuru.com.

It looks like the Treasure Coast surf will be increasing a bit.

The high tides are now pretty high.

Good hunting,

Treausreguide@comcast.net