Magnets that are strong for mint tins

[+eriicamurphy]

Anyone who places mint tin caches should know, which magnets do you use that are

A. Strong 

B. Fit inside tins

I’ve tried many small magnets (about 0.9cm) that aren’t strong enough to put on metal, even 6 of them. 

[+lee737]

I don't place mint tins - but other magnetic caches I've hidden will be similar.... you'll need a couple of rare earth magnets - probably 25mm diameter, 4mm thick - they'll do it nicely.

[+GeoElmo6000]

Please don't place mint tins.  They rust easily and I'm always afraid I'm going to injure myself opening rusty tins.

[+JL_HSTRE]

Mint cans rust easily and are never waterproof. The lids close snuggly but the hinges leak. They're simply not intended for outdoor use. One of the worst containers. 

[+Viajero Perdido]

AliExpress has a huge variety of rare-earth magnets at very modest prices.  If you don't like ordering from China (2-3wks), other big-name retailers like Amazon almost certainly carry them too.

 

Rare-earth magnets are crazy strong.  They'll be the only thing left after the tin has rusted away.

[+barefootjeff]

3 hours ago, JL_HSTRE said:

Mint cans rust easily and are never waterproof. The lids close snuggly but the hinges leak. They're simply not intended for outdoor use. One of the worst containers. 

 

Mint tins are the bane of my caching life. The lids aren't waterproof, they rapidly rust out and the narrow opening quickly turns whatever constituted the log into a scrunched up, tattered and torn lump. By all means place a magetic micro but please don't use a mint tin.

 

 

Edited January 9 by barefootjeff

[+Goldenwattle]

I can think of at least two mint tins which were a huge struggle to remove from their hides. And some others which also had too strong a magnet, but which I couldn't remove, and I had to make DNFs as I could not get the cache out to sign the log. A magnet can be too strong. Horrible caches in most situations, as they rust very quickly, and the log gets tatty very quickly too. (As barefootjeff wrote.)

[+colleda]

I like the magnets from old computer hard drives. Very strong.

[+Goldenwattle]

11 minutes ago, colleda said:

I like the magnets from old computer hard drives. Very strong.

They are likely some of those I have trouble removing. Nothing like a very strong magnet in a mintie tin in a pipe, too narrow to get a hand past the tin. Ridiculously strong and the cache can't be lifted from the structure, so it needs to be slid out, which is also almost impossible, especially with only fingers tip (and that barely), as no room for the whole hand.

Magnets can be TOO strong!

[+Calypso62]

10 hours ago, barefootjeff said:

 

Mint tins are the bane of my caching life. The lids aren't waterproof, they rapidly rust out and the narrow opening quickly turns whatever constituted the log into a scrunched up, tattered and torn lump. By all means place a magetic micro but please don't use a mint tin.

 

 

 

100% agree!!!!!!!!!!!

[+kunarion]

16 hours ago, Viajero Perdido said:

AliExpress has a huge variety of rare-earth magnets at very modest prices.

 

I've bought from there and from Temu.  You may find a pack of 20 round magnets for what a magnet specialty store charges for just one.  But it's not always clear what size they are.  The photo shows a huge magnet photoshopped onto a small hand.

 

I've also found small packs of magnets at hardware stores. In a limited supply.

 

And now I'm trying a pack of "magnetic phone holder replacement disks" from one of those shops.  When I can secure the magnet to a structure, a box with an attached magnetic mount can be placed in many creative places.

 

Edited January 10 by kunarion

[+kunarion]

On 1/9/2024 at 3:14 AM, lee737 said:

25mm diameter, 4mm thick - they'll do it nicely.

 

+1

That's my preferred size.  It's great for a lot of cache hide applications, and just one magnet can be strong enough for a Micro.  Maybe try gluing one inside and outside a Small lock-n-lock.  Or inside and outside the cap of a 50ml centrifuge tube.  The magnets hold each other well, and a little gorilla glue or something like it keeps them from sliding around.

 

Edited January 10 by kunarion

[+kunarion]

 

 

On 1/9/2024 at 3:09 AM, eriicamurphy said:

Anyone who places mint tin caches should know, which magnets do you use that are

A. Strong 

B. Fit inside tins

I’ve tried many small magnets (about 0.9cm) that aren’t strong enough to put on metal, even 6 of them. 

 

Stack rare earth magnets, or as you've tried, spread them out.  "0.9cm" is tiny for this application.

 

If a magnet is inside a magnetic box, it will need to be a much stronger magnet.  Ferrous plates are how magnets are shipped because the metal dampens the magnetic field.

 

I've only ever found one "mint tin" Micro outdoors, and it was rusted shut and full of water.  You have your work cut out for you, if you plan to maintain a viable cache.  Good luck! 

 

Edited January 10 by kunarion

[+Team Canary]

They really are not a suitable container. 

 

Buy something better than using leftover rubbish. A key holder, film canister, a decent size container, etc. Anything but a mint tin!!!

[+cerberus1]

Agree with Lee737, 25mm diameter, 4mm thick should do nicely.  I don't think I've ever seen one inside a mint tin (Altoids mostly) though. 

Similar to Goldenwattle, these cheaply made things are made to be pitched after use (I don't even use them for EDC small stuff anymore). Recycle.

Magnet too strong and the tin is mangled trying to get it off.  Remember we're dealing with other humans. Some in a hurry.   

So... I agree with others, here it's rusted with the cheapy bent metal hinge busted quickly.

The other 2/3rds cut her hand on a rusted-shut lid trying to open one once.  Guess depending on location, YMMV.  Good luck...

[+CheekyBrit]

On 1/9/2024 at 3:38 PM, barefootjeff said:

 

Mint tins are the bane of my caching life. 

Oh, you'll love this. My wife and I did a geo-art themed off of mint tins since they were the first few she found and she thought ALL geocaches were mint tins at first. (I can feel your dread, reading that).
We opted to use waterproof 50ml centrifuge containers for the series. It breaks the theme but I told her pretty much what this thread concluded.

[+kunarion]

5 hours ago, CheekyBrit said:

Oh, you'll love this. My wife and I did a geo-art themed off of mint tins since they were the first few she found and she thought ALL geocaches were mint tins at first. (I can feel your dread, reading that).
We opted to use waterproof 50ml centrifuge containers for the series. It breaks the theme but I told her pretty much what this thread concluded.

 

I love-love my 50ml tubes.  I also bought themed vinyl stickers for them.

[+Capt. Bob]

I agree with the previous responses that mint tins are a PITA.  The best alternative is a plastic container.  Consider the following when using a magnet for mounting.

 

The magnet should be a flat, round, as big as possible and mounted inside the container. The strength of the magnet should only be enough to secure the container and its contents to minimize stressing when removing the case.

 

The plastic surfaces should be cleaned with alcohol to remove contaminates (mold release, oils, etc.) then either rough or lightly flame treat (not melt) the plastic to break surface molecules bonds (also a good idea before applying paint).

 

The thermal coefficient of expansion of plastic is several orders of magnitude greater than the magnet.  So to mitigate stresses during temperature cycles the magnet should be attached with an adhesive that forms a flexible bond (like marine grade 3M 5200 Adhesive Sealant that offers both good cohesion and adhesion).  When applying the adhesive leave a thin layer of adhesive between mating surfaces to allow for expansion.

 

Remember that plastic cases are organic and are susceptible to the environment, such as sun light (UV), ozone, freezing temperatures, gnawing critters and, worse of all, humans.  Anything you can do to mitigate these other factors will enhance the container’s existence and reduce your maintenance.

Edited January 15 by Capt. Bob
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