A metal detector is a fairly specialized piece of electronic equipment and using one effectively takes some practice and know-how. This article will give you an idea of the types of features that modern detectors offer as well as some of the basic techniques of how to use a metal detector.
Swinging the detector
When using your machine to search, you will need to swing the unit back and forth over the ground, keeping the coil parallel to the ground as much as possible. You will also want to keep the coil as close to the ground as you can. If you’re hunting a yard for example, the bottom of your coil should brush the tops of the blades of grass as you swing. As you swing, don’t go too fast and keep it nice and even. You’ll get into a rhythm as you go and it will eventually became automatic.
If you don’t keep your coil parallel to the ground, you will miss targets, especially at the outer edges of where you’re swinging. If your coil isn’t kept close to the ground, you can lose significant depth. Develop good swinging technique early on and you’ll make the most out of any detector you have.
How to metal detect a site
Once you have secured permission to detect a site, putting a little thought into how you hunt it can help maximize your time and your finds. Think about the lay of the land and if you can, find out what used to be there. Especially if the site is large, it’s best to concentrate on places where human activity was most dense. This might be along sidewalks and driveways, around picnic tables, or at the entrances and exits of buildings (even if the buildings are long gone).
Once you have a particular area picked out, you will want to swing your coil over every square inch of it. The easiest way to do this is to “grid out” an area. Some detectorists will just imagine this grid, walking down the grid lines one after another until an area is completely searched. Others have been known to use colored flags or another type of marker to show where a line begins or ends. Whatever method you choose, make sure that where you’re swinging along one grid line overlaps with the last. Overlapping swings along your grid will lessen your chances of missing good targets.
How to dig a plug
Retrieving the targets that you find with your metal detector will involve digging. This means digging a hole and cutting through grass and dirt to get to that target. Doing this in a way that won’t scar a yard or kill grass takes a little technique and practice, but it’s not complicated.
Once you have identified your target and have a firm idea of where it is (for more on this, see “Pinpointing” below), use a hand digger or spade to cut in a circle around where the target is. But here’s the kicker: don’t cut all the way around. Cut about 75% around your circular plug and stop. Then use your digger to pry your plug up and back, using the grass that you didn’t cut through as a hinge. Once you have the target, replace your plug with the hinge intact and tamp it down until it sits properly at ground level and blends with the surrounding grass. When used properly, this technique helps keep the existing grass roots hydrated and should leave essentially no trace of your digging.
How to use your metal detector settings
Metal detectors have come a long way in the last few decades. Many of the features that were only available on high-end detectors in the 1980s and 1990s are standard on inexpensive machines today.
Essentially all modern detectors will include some form of target ID. In practical terms, this means that the machine can tell the detectorist, with relative accuracy, what the target is made of before it is dug up. Silver and copper tend to be at the top of the range, gold and smaller pieces of aluminum are in the middle, and iron is at the lower end of the spectrum. The machine will provide this information in two ways: via audio and, oftentimes, a digital display. Most detectors have multiple audio tones that indicate what range a signal falls in: a low tone, a mid-tone, and a high tone. There is also generally a visual display that will give you a numerical value (an iron nail might be a 10, while a quarter might ring up at 85) or represent the signal you’re getting along a spectrum from iron to silver.
Modern detectors will also include a discrimination feature which will allow the user to differentiate one type of metal from another, especially iron from non-iron targets. Many detectors with this feature can also be set to discriminate out certain types of signals, like iron or pulltabs. While discrimination is a great feature, it isn’t a magic bullet. Gold and pulltabs can sound identical, so discriminating out pulltabs might make you miss a gold ring!
Pinpointing is another common feature. One of the biggest practical challenges of detecting can be finding a small target once the hole has been dug. The pinpoint function on a detector will, usually at the push a button, give off a constant tone when your search coin is centered over your target, allowing you to narrow down your search for the target. We’ll discuss other methods of pinpointing in the next section.
Using a pinpointer
As a general rule, it takes time and practice to get good at pinpointing, but the right techniques and equipment can help you get there faster.
I highly recommend you purchase a pinpointer, essentially a small, handheld metal detector used primarily to locate the target after you’ve already dug your hole. It’s not unusual for these to cut target recovery time in half, so if you have the money to spend, it’s a must buy. The Garrett Pro-Pointer is most common in the metal detecting world, but there are plenty of other options.
There are also a couple of tricks to use as you become more experienced. The simplest “trick” to remember is that if you have a solid, repeatable signal, it must be under your search coil. Use the outline of your search coil as a guide for the size and shape of your plug and you’ll be a step in the right direction. The second trick is sometimes referred to as “bouncing”. This is a more advanced technique in which the detectorist will, once over a solid, repeatable target, swing rapidly side to side over the target in order to pinpoint its location without using the pinpoint function. This takes practice and experience with your machine, but it is effective and can cut down recovery time as well.
Other things to consider
There are many other things to consider such as false signals, trashy areas, and EMI.
Some signals can throw your detector for a loop and cause it to misrepresent what’s actually in the ground. These problems can affect all detectors, from budget models all the way to top-of-the-line machines. The most common reason for this is rusty iron in the ground. As a piece of iron rusts, bits of that object will spread out and form a “halo” around the target, making it seem larger than it is. This can cause falsing, especially when the iron is deep. In rare cases, false signals can also be the result of a malfunction in your detector.
Metal detecting can show you just how much trash human activity can create – some sites more than others. Schools, parks, and even yards next to a major roadway are often victims of those who litter, with crushed or shredded cans (known as “canslaw” amongst detectorists), bottlecaps, pulltabs, and other metallic trash creating a barrier between you and desirable targets. Other than avoiding these locations, what can you do? One school of thought is to intentionally dig the trash to clean up the site and reveal what might be hidden underneath. This can work, but is time consuming and will eventually test one’s patience. Another way is to use a small coil and go slow, picking out good signals amongst the trash. Either way, these sites can be grueling, but if there is potential for good finds at your site, it might be worth the time.
Detectors function by using electromagnetic fields to locate metal objects, but these fields can be disrupted by power lines, other detectors, and even solar activity. Some sites have especially strong electromagnetic interference (EMI), making it difficult or impossible to detect. This can sometimes be mitigated by changing frequencies on your detector (check your owner’s manual), turning down your sensitivity, or coming back at another time of day when the interference is less severe.
There can be a learning curve associated with metal detecting, but the best way to learn after reading up and getting your bearings is to go out there and detect. So keep your coil to the soil and happy hunting!