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The good and bad effects of wet Vs dry dirt.

September 16, 2020 01:21PM avatar
First we need to clarify just what a 'wet' environment is with regard to metal detecting. We could look at 'moisture' as being dew on a morning lawn, a light shower leaving the grass and shallow surface damp to sort-of wet. In those two cases we are not going to see much impact on a metal detector's performance.

What we do need to be aware of is ground that is significantly 'wet' to the point of being 'saturated' with water ... and to what level the water is saturated. We also should consider the ground mineral make-up and any effects saturated water might have on the ground effect.


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dixiedigger57
I have always heard many things affect detecting like EMI, tides, gravitational pull, phases of moon even, and specifically and more applicable wet dirt. its soft to dig but just plain messy.

Forget the moon, gravity, tides and such because I have started interesting discussions just about water. But that's another topic. eye popping smiley Enjoy your detecting, even if you have to deal with mud. Me? I wouldn't because I don't like muddy environments so I'd head for high ground ... or some dry location to work on research.


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dixiedigger57
Does the wet ground actually have that much affect on ferrous and non ferrous targets?

Yes, and No in that order ... kind of.

As for Non-Ferrous targets, a wetted, saturated environment will have very little effect, and that is because non-ferrous targets, such as a Copper 1¢ or Clad or Silver 10¢ coin doesn't decay and corrode like a Ferrous target might. In short, there is no decomposition and therefore there is no 'halo' effect from a Non-Ferrous target.

Now we get to the tricky topic of a Ferrous or Iron or a Magnetic-Metal target. Metal targets in this group are more likely to corrode or decay due water, salt or other ground chemical interaction. Due to the fact that a Ferrous object in this group 'might' corrode, there is the possibility that there might be enough surface-metal breakdown deposited on or closely adjacent to the Ferrous object that there might be the potential for a 'halo effect.'

But if so, those loose decaying ferrous pieces would have already had an effect on the discarded ferrous object when it was a dry environment. What effect? Simple. If it happed to be an Iron Nail that measured 4" long and had a thickness of ¼" when it was lost, then it would produce a certain audio and visual response when detected. If it wasn't Discriminated out, you would hear the target's response. If that Iron Nail was positioned close to a Non-Ferrous Indian Head 1¢, there could be some partial target masking caused by the Ferrous object which has a greater effect on the EMF than a Non-Ferrous object.

Now, let's imagine that both the Iron Nail and the Indian Head had been stepped on by some cattle and were now out-of-sight and located maybe 2" deep ... and have been for 150 years. Then, you come along with your metal detector ready to find something exciting. What's going to happen? Well, it could be several things:


If they have been undisturbed for 150 years they should still be in the same location. The Indian Head's detectability would be partially determined by how close the Iron Nail was and the detector and coil used as well as direction of sweep.

If it is a dry and arid region with very little precipitation, then being located a couple inches deep and without a saturated water level and without an open-air environment, the amount of rusting or the progression of the rusting of the Ferrous Nail will be very slow. Therefore, the Iron Nail would be relatively unchanged from the effect it would have had if you went through there detecting the day after the cattle stomped them out of sight.

Let' say it is an area that gets a lot of 'seasonal' weather and there has been a lot of rain, at times, or even heavy winter snow that melts, and both the melting snow and rain events left the ground very wet, saturating it to and beyond the depth of the Iron Nail and Indian Head 1¢. Then, after a long, dry summer you happen upon the spot with detector in-hand. What can you expect?

After 150 years of seasonal events that would have saturated the ground and exposed the Iron Nail to enough water to 'soak it,' the saturated effects along with the oxygen carried by the exposure to the water would have most likely had a negative effect on the Iron Nail. It would be rusted, at least on the metal surface, but quite possibly it would have deteriorated or corroded more of the surface metal.

Most of that decayed metal would be rusted 'particles' and in a dry environment have little effect on the EMF. The Iron Nail itself, a century-and-a-half later, would now be decayed to a slightly smaller-in-size. Therefore, it would have slightly less negative effect, or less good-target masking, than years ago.

Also note that in a more salty environment, such as having an Iron Nail lost on a coastal wet beach environment or perhaps in an alkaline soil that also gets seasonal amounts of very wet conditions, the wet-salt conditions will likely expedite the Ferrous metal's decay. Even to the point that you might look and SEE what appears to be an Iron Nail, or the remains of one, but it is nothing more than decayed matter that is barely together to hold a shape or form. I have five old crown-type Bottle Caps in my seminar tote that will NOT give you any false reading. Matter of fact, they usually will not produce ANY reading, even with a Pulse Induction detector on a VLF in a Zero Disc. mode or even in All Metal mode.

Okay, now we'll get to hunting a site like described, except it is now very wet from a lot of heavy rain and the ground is very saturated with it being soaked to 6" deep and the Iron Nail and Indian Head Cent are still at the 2" mark. When you arrive on the scene there are three things that might be noted:

1.. If they have been undisturbed for 150 years, then a saturated condition might result is a little enhanced negative effect from the Iron Nail IF there is enough close particulate mater and the Iron Nail hasn't decomposed very much.

2.. It might be a saturated wet environment, but over the past 150 years there has been enough break-down and loss of the surface metal of the Iron Nail that, even if there are close particles of sufficient size adjacent to the Iron Nail, the reduced size of the Nail means the trade-off would about eliminate any perceived 'halo' effect.

3.. Upon your arrival at the site in a very saturated, storm-drenched muddy environment, you step too close to the Iron Nail and Indian Head and perhaps mush them around, push them deeper, or possibly even bring those 2" deep objects to the surface. You find the Indian Head and the search is over .... OR .... you simply reposition them and the 150 year period starts all over again.sad smiley



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dixiedigger57
i am familiar with halo effect--the blasted older bottlecaps that spread out in a rust circle. water conducts.

Any perceived 'halo' effect caused by deteriorating ferrous / magnetic metal is only going to be annoying if it is a very wet, saturated condition, and if there is sufficient 'rusting' such that any minute effect it would have on the EMF is going to be noted only when such a condition is in contact with the Bottle Cap itself. The real problem is the Bottle Cap and not any so-called 'halo' effect because the broken-down particles do not combine to cause the same effect as the whole Bottle Cap before it starts to decay.

Also, a Bottle Cap is a nuclease simply because man took some Ferrous material and shaped in such a way that it pesters a detectors EMF. I can use any of my detectors and hunt common urban sites or old picnic ground were I encounter a lot of Bottle Caps and usually 'classify' them without much trouble. Most of them are relatively shallow, from on the surface to perhaps 3". If I know I am going to Coin Hunt an area with a disproportionate number of Bottle Caps, I would grab one of my two favorite detectors to take on those pesky targets. My White's XLT that has a "Bottle Cap Reject" function, or the new Garrett Apex where I can Coin Hunt, but make use of the 'Iron Audio' feature to help classify most Bottle Caps.

To tell you the truth, with over 55 years of avid detecting, I have never had much of a challenge from Bottle Caps, be it a wet or dry environment.


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dixiedigger57
... but we have water machines... does it affect GB and mineralization more?

First, our "water machines" simply means they are submersible, and the better designs can work well the coastal waters to handle the wet salt environment. Water, or 'wet ground' as-in inland ground that isn't salt water, might have some issues caused by being wet if the ground is a problem mineralized dirt and if the wetness is actually a saturated wet environment.

Here we get into the ground mineral make-up, and if it is 'layered' dirt, such as maybe a very mineralized layer of dirt from 4" on down a ways and lower-mineralized dirt in the upper 4" depth. Or, it could be the other way around where a higher-mineralized dirt could be in the upper 4" and less mineralized dirt from the 4" depth on down deeper.

If it is just plain old water, and the dirt is not alkaline, then there might be very little negative effect, or it could result in some highly mineralized ground seeming to me a slightly more mineralized. If a detector has GB capability, no major problem. If the unit relies on a fixed or preset GB, then it might not be a more favorable setting to handle the ground.

If there is ample water and if it is an alkaline environment, it could be a saltwater type effect and the mix would result in a very low-conductive environment that would have to be dealt with. That could include some GB adjustment, using a 'salt' or 'beach' offset GB, or simply adjusting the GB to the existing 'dry' ground condition, then using a very low level of Discrimination to reject the low-conductive wet alkaline condition that should be just blow typical Foil ejection.


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dixiedigger57
make targets actually more sensitive or actually too much?

Generally not a + or - situation. Often it would be of an issue to deal with any ground mineral influence from a lot of wetness.


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dixiedigger57
just want a good explanation on this wet effect. this weekend if i get to hunt in will be in mud soup.

I hope I was of some help, but if not, look at the bright side. It should have taken you long enough to read it all and decipher what I said that the weekend will have arrived and you can head out detecting.winking smiley

Monte

"Your EYES ... the only 100% accurate form of Discrimination!"

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Subject Author Views Posted

since we are getting a ton of rain.. wet dirt question..

dixiedigger57 75 September 16, 2020 09:51AM

wet dirt question..

UtahRich 42 September 16, 2020 07:56PM

I like moist ground condition....

Hombre 46 September 16, 2020 06:34PM

The good and bad effects of wet Vs dry dirt.

Monte 62 September 16, 2020 01:21PM

Re: The good and bad effects of wet Vs dry dirt.

dixiedigger57 51 September 16, 2020 02:02PM

Re: The good and bad effects of wet Vs dry dirt.

Druid 41 September 16, 2020 06:22PM

Re: The good and bad effects of wet Vs dry dirt.

Senior Deacon 47 September 16, 2020 07:35PM

Re: The good and bad effects of wet Vs dry dirt.

dixiedigger57 37 September 17, 2020 01:35PM



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