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Dealing with those pesky bottle caps

I've found those steel bottle caps have a few stages/lifetimes in the water...

1) Brand new Coronas, Budweiser/light, and a few others sound just like a coin..

2) Once rusted enough they will have a halo that wants to fool you into a high tone...

3) Once totally rusted but just holding shape, my machine will start to pick out the mid tone, which is the aluminum foil seal inside the steel..

4) Steel is all gone, aluminum circle shaped seal sounds like perfect gold jewelry signal till removed from the looting grounds...

<°)))>{
 
Lots of good observations on bottle caps. I have used several methods. I like to raise the coil on my machines. Bottle cap ids tend to bounce wildly as you raise the coil. Quarters tend to lock on or bounce just a couple numbers as you raise the coil until signal fades away. Worked on all machines I have owned. To me they also tend to sound differently, especially if you learn your machine thoroughly.
 
The problem with ferrous bottle caps is - well, they rust. Once the metal has rusted through, even in just a portion of the cap, that rusted through metal will appear to the metal detector as a highly conductive object. This is one of the reasons why rusted through nails show up as good targets as well.

Fortunately for us, if there are parts of the cap that are not rusted through, they will behave differently when the coil sweeps over them at different directions. Iron is wonderful in the fact that when you sweep on one direction you will get one response, but when you sweep in a direction 90 degrees from the first sweep, you will get an entirely different response.
 
The problem with iron bottle caps is that they are thin (in comparison with large surface) and are with large surface, and are located on beaches...

Thin iron objects with large surface (caps, cans, helmets etc) will produce non ferrous signals (especially large deep ones) on majority of VLF detectors.
Q: Why?
A: Every signal consists of magnetic part and conductive part. Non ferrous objects have reduced magnetic part and large conductive part. Thin iron objects with large surface have almost the same parameters non ferrous targets have.

Q: How can I avoid digging thin iron with large surface?
A: Start using algorithms those pay especial attention to magnetic qualities of target. Start using low frequency coils (E.g. 3 kHz), they are less sensitive to thin rusted iron, these coils will ignore tiny rusted objects within tiny gold stuff :wow:. If you are a beach hunter, 3 kHz coils is no way to use, then you can help yr detector to recognise thin iron by reducing electro-magnetic field by a) scanning with the edge of coil b) raising coil above target c) altering coil orientation by 45 degrees to a target d)reducing output amperage/voltage e) a+b+c+d.

HH
 
If I was more of a dirt guy, I would have kept my T2 it had a bottle cap program that allowed me to hunt with confidence in parks loaded with caps... it would sound off in one direction but null in the other so I knew it was a bottle cap.. to make sure I dug a few..
 
For the minelab quattro it is easy to determine an iron bottlecaps, in all metal mode ferro tones a bottle cap will give a jumpy target id or will be in 12-26 number but will give a high pitch tone. Remember that 12-30 number will give a middle tone so everything that give a high pitch sound and middle to lower target id are definately bottlecap or junk.
 
Get an Etrac. Etrac has no problems with Bottle Caps and it will pick up a Screw Cap especially crushed ones at 12" with nails all around it.
 
Bottle caps is so easy to determine if you just learned the machine..about screw cap with nails around it i dont think so if etrac can still pick it up if the nails are shollower than it and side to side distance is about 1-3 inches.
 
Bottle caps is so easy to determine if you just learned the machine..about screw cap with nails around it i dont think so if etrac can still pick it up if the nails are shollower than it and side to side distance is about 1-3 inches.

I think my Etrac can pick up a Screw Cap in the Pickup driving by a Vacant Lot. Pinpointing is hard though.
 
When steel bottle caps become a problem for me with a Tesoro machine, I find that switching back to a concentric coil makes all the difference. The concentric coil will easily identify steel bottle caps where my wide scan or DD coils won't.
 
What is wrong with you guys. Talking about all them different detectors and how to tell if it is a bottle cap or coin.

I am going to tell you how I do it and it is fool proof...




I just hold the stupid cap in one hand and a coin in the other hand. I look very careful at each one.

I can pick out the coin with my eyes closed................ Every time.

That's how I do it... KEN
 
My M6 just loves those dark purple screw tops. You just can't teach it that they are not quarters!:D
 
When steel bottle caps become a problem for me with a Tesoro machine, I find that switching back to a concentric coil makes all the difference. The concentric coil will easily identify steel bottle caps where my wide scan or DD coils won't.
I have two tesoro's now- tejon and a cibola. I agree - so far only had problems with my DD reading screw caps as coins. Concentrics dont. That being said, on the tejon you can easily tell the difference by switching tone to vco, and then pulling the all-metal trigger. The difference between screw cap and coin is night and day - a screw cap or can will blow your ears off! (Trick stolen from another forum somewhere, can't remember).

Sent from my SAMSUNG-SM-G900A using Tapatalk
 
If I was more of a dirt guy, I would have kept my T2 it had a bottle cap program that allowed me to hunt with confidence in parks loaded with caps... it would sound off in one direction but null in the other so I knew it was a bottle cap.. to make sure I dug a few..
I seem to have to dig a few before selecting 3b......:blush:
 
Lots of good observations on bottle caps. I have used several methods. I like to raise the coil on my machines. Bottle cap ids tend to bounce wildly as you raise the coil. Quarters tend to lock on or bounce just a couple numbers as you raise the coil until signal fades away. Worked on all machines I have owned. To me they also tend to sound differently, especially if you learn your machine thoroughly.

+2:yes::yes:
 
The MXT discrimination and sensitivity is such that many bottle caps (the crimped steel ones) will ID as a good quarter or dime signal, depending on how rusty they are, when your coil sweeps are centered over them.

The XLT and DFX, with their Signagraph capability, have an easier time of it. The Signagraph will show the target with multiple separated bars and give the bottle cap away.

When I am hunting with my MXT in an area where these bottle caps are plentiful, the easiest way to identify them, rather than digging them, is to take another pass over them in discriminate mode, but this time do it with the edge of the coil, instead of the coil centered on the target. "Rimming" the target this way will let the detector show them up as ferrous targets. This technique will work with just about any VLF detector.

Try it!



Rudy... when you say discriminate mode how much disc are you talking about? Where do you set it to check for a cap? I ask because I mainly hunt in Relic mode with zero disc and two tone... I only ask if I was to hunt a park which would be a rare occurrence ;)
 
Rudy... when you say discriminate mode how much disc are you talking about? Where do you set it to check for a cap? I ask because I mainly hunt in Relic mode with zero disc and two tone... I only ask if I was to hunt a park which would be a rare occurrence ;)

Craig, I normally run it with the discrimination set to discriminate a small nail. If too trashy, I'll set it to just below a nickel.

I primarily use C&J, but Relic with zero disc and two tone would drive me crazy.
 
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