Attaching a magnetic container for geocaching: How to make sure your cache stays put
A magnet container only holds reliably if three things match: a steel or iron surface, a magnet firmly attached to the container, and a flat, clean contact surface without an air gap. Check the surface on site with a small test magnet, place the cache in a smooth spot protected from direct rain, and find out beforehand if the owner agrees. In this guide, we show you step by step how to attach your magnet cache, which container suits which hiding spot, and what you need to think about so that finders can still log it in two years.
Key Takeaways
- Only ferromagnetic surfaces hold: Steel and iron yes, wood, glass, plastic, concrete and aluminum no. Stainless steel is not automatically magnetic; a test on site clarifies this in seconds.
- Every millimeter of distance costs holding power: Thick paint, rust, dirt or a curved surface significantly weaken the magnet.
- The magnet must be secured in two ways: Weatherproof adhesive plus a mechanical securement, such as fabric tape or a cover, prevents the magnet from coming loose after a few winters.
- Camouflage yes, barrier no: The cache should be inconspicuous, but remain accessible permanently and without tools.
- No hiding spot without permission: Private property must not be damaged, and for caches in the forest, separate rules of the state forestry services apply in Germany.
Table of Contents
- On which surfaces your magnet cache holds
- Attaching a magnet container: Step by step
- Permanently attaching the magnet to the container
- Which magnet container suits which hiding spot?
- Camouflaging inconspicuously without making the cache inaccessible
- Moisture, dirt and rust: how to keep the logbook dry
- Permission and rules in Germany
- Our view from the workshop
- Magnet hiding spots from CacheWerk for your next cache
- Frequently asked questions about attaching magnet caches
- Sources
On which surfaces your magnet cache holds
Before you think about adhesive or camouflage, the most important question remains: Will the magnet hold at all? A magnet needs a ferromagnetic surface. With stainless steel, a closer look is worthwhile, because stainless steel is not automatically magnetic. Some grades attract the magnet strongly, others not at all. A simple refrigerator magnet in your jacket pocket will save you a lot of trouble here.
Just as important is how the surface is designed. According to the standard parts manufacturer Elesa+Ganter, an air gap or non-conductive materials between the magnet and the workpiece reduce the holding force, and the greater the distance, the stronger the effect. Also, high roughness, unevenness and insufficient material thickness weaken the holding force. The tool manufacturer FEIN also calls an unpainted, rust-free and flat surface a prerequisite for optimal adhesion for its magnetic technology and points out that aluminum and many grades of stainless steel do not work.
For you as an owner, this means in practice:
| Surface | Will the magnet hold? | What to look out for |
|---|---|---|
| Unpainted steel, steel beams | Yes, very well | Wipe off surface rust beforehand |
| Painted steel surfaces, railings | Yes | Thick paint layers or powder coating weaken the adhesion |
| Cast iron, old grates, iron bollards | Yes | Avoid rough spots, look for a smooth surface |
| Thin sheet metal, e.g. control box cover | Limited | Thin material holds less, test the hold on site |
| Stainless steel | Depending on the grade | Always check with a test magnet |
| Aluminum, copper, brass | No | Choose another attachment method |
| Wood, plastic, glass, concrete, stone | No | Unsuitable for magnet caches |
A good test on site: Place your finished cache in the desired spot and pull it off sideways, not vertically. This is exactly how the finder will stress it later, and a magnet slips sideways much more easily than it lets go directly.
Attaching a magnet container: Step by step
This is how you proceed when placing a new magnet cache:
- Choose a hiding spot: Look for a spot that is easily accessible, where finders can safely stand, and where nothing will be damaged. Locations directly in traffic or at railway facilities are ruled out.
- Clarify permission: Ask the owner or operator before you start. More on this further down in the section on rules.
- Check the surface: Place the test magnet, assess the material and paint layer, and look for the flat spot.
- Clean the surface: Remove dust, cobwebs and loose rust particles with a cloth. Every layer of dirt is a small air gap.
- Place the cache and check the position: The lid should point downwards or to the side as much as possible, so that rain does not hit the opening directly.
- Perform a pull test: Pull sideways and diagonally. If the cache holds securely during this, the position is good.
- Measure the coordinates: Take several measurements and average them, especially between metal structures and buildings, the GPS signal fluctuates.
- Take a photo: A photo for yourself helps with later maintenance visits and with questions from finders.
You can find detailed instructions with all work steps from construction to placement in our Geocache Magnet Building Workflow.
Staying safe while placing and maintaining
Magnet caches are often attached to railings, under bridges, or to metal structures. There, you can quickly grab a sharp edge or slip on a wet surface. Therefore, pack a small first-aid kit in your cacher bag, with plasters, disinfectant, and a triangular bandage for the emergency bag, which can also be used as a sling or pressure bandage. Gloves additionally protect against rust and burrs during maintenance.
Permanently attaching the magnet to the container
If you buy a ready-made magnet container, the magnet is already built in. If you build one yourself, such as a magnetic PETling, the connection between the magnet and the container determines the lifespan of your cache. Outdoors, the material is constantly working: In summer, a steel railing heats up in the sun, in winter it gets frost. Household adhesives and hot glue often become brittle and come loose.
This combination has proven itself among cachers:
- Weatherproof construction adhesive: Choose an adhesive designed for outdoor use and temperature changes that remains elastic.
- Mechanical securement: A strip of fabric adhesive tape that runs completely around the PETling once and overlaps holds the magnet in place even if the adhesive gives way after years.
- Alternative cover: A piece of old bicycle inner tube over the container, under which the magnet is slid, creates a robust external attachment without adhesive.
Pay attention to two details: The magnet should lie as flat as possible on the surface, and later too much material should not lie between the magnet and the surface. A thick layer of adhesive tape over the magnet surface is an air gap that costs you holding power. Two small, strong neodymium magnets next to each other usually hold better than one large one, because the container does not tip over as easily.
How to implement this cleanly, we show you in our guide Attaching a PETling magnet weatherproofly. And if you want to know how magnets and 3D-printed parts are protected from moisture outdoors, read our post on Coating and mounting for outdoor hiding spots.
Which magnet container suits which hiding spot?
There is no single best magnet container. There is the right one for your hiding spot. The question is always: How much space do I have, how exposed is the location to weather and prying eyes, and how much log should fit inside?
For micro magnet caches, according to CacheWiki PETlings, the container should be robust and weatherproof. Household tin cans, film cans, and small jars with narrow necks are considered unsuitable there. A magnetic nano, on the other hand, is a tiny metal container with a screw lid and magnet on the bottom, usually with an O-ring, which makes opening easier and partially waterproofs it.
This is how you compare the common types:
| Type | Typical hiding spot | Logbook | Strengths |
|---|---|---|---|
| Magnetic nano | Railings, signs, steel beams in the city | Log strip | Tiny, quickly hidden, ideal for tricky city caches |
| Screw or bolt with secret compartment and magnet | Metal structures, fences, machines | Log strip | Looks like a normal component, perfect camouflage |
| Wing nut cache | Urban hiding spots among real screws and nuts | Log strip | Blends in inconspicuously into metal environments |
| Magnetic PETling | Undersides of railings, steel frames | Small logbook or long strip | More space for logs, easy to open |
What to look out for when comparing:
- Seal: An O-ring or a good thread seal keeps most of the moisture out.
- Opening with cold fingers: In winter, a finder must be able to open the lid even with clammy hands.
- Log volume: In popular city caches, a log strip fills up quickly. Plan regular maintenance or choose a larger container.
- Camouflage: If the cache looks like a part of its surroundings, it will be taken by uninvolved people less often.
- Magnet strength matching the size: Small containers need small, strong magnets. Magnets that are too large make a mini container unnecessarily difficult to release.
Even more background on the individual designs and magnet types can be found in our overview Geocaching magnet containers explained. Inspiration for concrete hiding spots is provided by our Magnet cache ideas for owners.
Camouflaging inconspicuously without making the cache inaccessible
A good magnet cache does not catch the eye of muggles, but is surely findable for cachers with a little searching. The trick is to adapt the container to its surroundings:
- Color: A black cache disappears on dark steel beams, a gray one on galvanized railings. Many owners re-wrap PETlings with black, green, or white tape to match.
- Shape: Screws, nuts, or bolts with secret compartments look like a normal component on metal structures.
- Position: Undersides and inner edges are protected from prying eyes and rain.
- Labeling: A small note like "Geocache, not trash" inside or on the container helps if someone uninvolved finds it.
Important: Camouflage must never become a barrier. The geocaching magazine emphasizes that the accessibility of the geocache must be ensured long-term and without restrictions. For magnet caches, this means: No spots that can only be reached with tools or a ladder, no crevices from which the cache can only be removed by force. And neither during placing nor searching may private property be damaged.
Moisture, dirt and rust: how to keep the logbook dry
Rain is the natural enemy of every log strip. Even nanos with an O-ring are not completely weatherproof: If water penetrates, the log strip sticks and can hardly be pulled out anymore. This is how you prevent it:
- Opening downwards: Place the cache so that the lid does not point upwards and rainwater drains off.
- Choose a protected spot: Under an overhang or on the inside of a beam, less water hits the container.
- Weatherproof log material: A waterproof log strip survives moisture significantly better than normal paper.
- No plastic bags: CacheWiki advises against using plastic bags as protection for cache containers, because they usually become full of holes after just a few weeks and then keep the cache damp and dirty. A piece of fine mesh in earth tones is better suited as camouflage, through which moisture can escape.
- Maintain the seal: During maintenance visits, briefly clean the O-ring and check if it is still elastic.
- Keep an eye on rust: Surface rust on the substrate reduces adhesion. A quick wipe with the cloth during a maintenance visit helps.
Plan a check-up at least once after winter and after periods of heavy rain. The logs from your finders will also alert you early if a strip gets damp or the lid sticks.
Permission and Rules in Germany
In Germany, the rule is: A cache may only be placed where the owner has given permission. The Geocaching.com Wiki for Germany warns that hiding a cache without the owner's permission can lead to criminal charges against the owner and participants. Each owner is personally responsible for choosing the hiding location; no reviewer can authorize a hiding location or provide legal advice. According to the wiki, caches with holders in the forest may only be activated with written permission from the forest owner and a corresponding note in the listing.
For magnet caches in the city, this means specifically: railings, signs, masts, and control boxes almost always belong to the municipality, a utility company, or a private owner. Ask them before attaching your cache, and keep a record of their permission.
In the forest, the states and forestry companies regulate the details. Two examples:
- Saxony: The information sheet of the state-owned Sachsenforst company stipulates that caches in the forest should be no larger than a cookie or breakfast tin, must not adversely affect the forest, and must not be attached to trees with nails or other bark-damaging fasteners.
- Lower Saxony: In the Lower Saxony State Forests, nature-friendly geocaching for recreational purposes is generally permitted, provided it is not commercial or organized, does not violate nature conservation regulations, and does not cause noticeable damage to trees. Other landowners may require permission on a case-by-case basis.
The great advantage of a magnet cache: It requires neither screws nor adhesive at the hiding location. You leave no drill holes or residues, and when archiving it, you simply take it with you.
Our View from the Workshop
We cache ourselves, and that is exactly where our magnet caches came from. We have found tins time and again whose magnet had come loose or whose log strip was nothing more than a wet lump. That is why we develop and test our caches so that they withstand the elements: on steel railings in the city as well as on metal structures in rural areas.
Our experience: A magnet cache lasts longest when it looks like part of its surroundings. A screw among screws, a cap nut among cap nuts, a black nano on a black beam. This keeps your cache invisible to muggles and a real, enjoyable challenge for cachers.
We 3D print many of our special parts in PETG because this allows us to create well-thought-out shapes that are not available off the shelf. And if your cache needs something special, get in touch: custom solutions are part of our everyday business.
Benedikt
Magnet Caches from CacheWerk for Your Next Cache
You don't want to tinker, but place a cache right away? Then take a look at our ready-made magnet caches. The Black Magna Nano Cache is a magnetic nano with a log strip for tricky urban hiding locations. You can get our screw with secret compartment and magnet in a pack of two, and the stainless steel cap nut cache is a waterproof urban nano with a magnet.
You can find logbooks, spare parts, and other accessories for owners in our Equipment and Accessories category. Our practical report on the CacheWerk PETling shows you how our PETling with a magnet holder performs in practice.
Frequently Asked Questions About Attaching Magnet Caches
Does a magnet cache stick to stainless steel?
That depends on the grade of stainless steel. Some grades are magnetic, others are not. Check the spot with a small test magnet before placing your cache there.
Why does my magnet cache keep falling off?
It is usually due to the substrate or the distance: thick paint, rust, dirt, or a curved surface reduce the holding power. Find a smooth, clean spot and perform a side pull test. If the magnet has come loose from the container, secure it mechanically as well, for example with fabric tape.
Can I attach a magnet cache to a traffic sign or railing?
Only with the owner's permission, which in the city is often the municipality. Without permission, you risk criminal charges according to the German geocaching wiki. Also choose locations where finders can stand safely and do not have to step into traffic.
How often should I maintain a magnet cache?
Plan a visit at least once after winter and after long periods of rain. Check the seal, log strip, and the magnet's hold. Hints in your finders' logs are a good signal for an unscheduled check.
Which magnet container is best for beginners?
For getting started, a magnetic nano or PETling on a well-accessible steel railing is suitable. Both are quick to place and easy to maintain. Those who want more camouflage should opt for screw or cap nut caches.
Sources
- Magnetic solutions: working principle, limitations, and substrates (wohnen-ohne-bohren.de)
- Holding magnets / raw magnets, technical data (Elesa+Ganter)
- FEIN VersaMAG System (C. & E. Fein GmbH)
- Hiding geocaches (CacheWiki)
- Magnetic nano (Wikipedia)
- Placing and hiding geocaches: tips for beginners (Geocaching-Magazin)
- Germany, Geocaching.com Wiki
- Geocaching in the forest, tips and information (Saxony information sheet, 2023)
- Geocaching in the state forests (Lower Saxony State Forests)