Wednesday, 20 January 2021

anti-magnetic issues (and your watch)

 an old saying is something like "knows just enough to be dangerous" ...

One of the things that the King Wang New Watch Purchaser today seems to fuss about is accuracy, its pretty common for the new watch owner to expect that their new object of fascination should be accurate to within seconds per day (and they'll check every day).

One of the things which emerges quickly is it's not up to swiss cronometer standard, and Google "my watch is [slow | fast]" and may find a suggestion that the cause is "your watch has been magnetised" ... frankly I'm of the view that 90% of the population don't have the faintest idea what magentism even means.

So if you're wondering if your watch is running fast or slow because its been magnetised then the first thing you should do is look for this symbol on your watch

That symbol tells you that the watch is resistant to being magnetised. In the case of Seiko it goes like this:

Seiko case back markings

  1. No inverted U indication: certified level of anti-magnetism: 1,600 A/m. Your watch will not be affected by the level of magnetism that ordinary watches can withstand.
  2. Inverted U with 1 bar (Type 1): certified level of anti-magnetism: 4,800 A/m. Your watch will not be affected by the magnetism generated by household appliances at a distance down to 5cm.
  3. Inverted U with 2 bar (Type 2): certified level of anti-magnetism: 16,000 A/m. Your watch will not be affected by the magnetism generated by household appliances at a distance down to 1cm.

Now the normal standard for Japan made stuff (and that means the movement) is that its like this

Magnetic resistance performance

TypeMagnetism resistance
(in case of direct
current magnetic field)
Common timepieceUp to 1,600 A/m
(approx. 20 gauss)
The minimum magnetism resistance requirement for a watch. (For reference)
Type 1 antimagnetic watch
(magnetic resistant watch)
Up to 4,800 A/m
(approx. 60 gauss)
A magnetic resistant watch almost always maintains its performance when placed at 5 cm from magnetic field generating devices of everyday life.
Type 2 antimagnetic watch
(super magnetic resistant watch)
Up to 16,000 A/m
(approx. 200 gauss)
A super magnetic resistant watch almost always maintains its performance when placed at 1 cm from magnetic field generating devices of everyday life.
Diver's watchUp to 4,800 A/m
(approx. 60 gauss)
The magnetism resistance requirement for a diver's watch.
  • Type 1 and 2 requirements are defined in JIS B 7024 - Magnetic resistant watches, and diver's watch requirements in JIS B 7023 - Divers' watches - Classification and performance.
  • Generally, resistance of watches is indicated according to the old JIS B 7024 standard, but indications are now being changed for the current ISO standards.

referencing this site.

So what does this A/m and gauss mean?

Well like most things there is a measurement for it, like how much water is in a bucket, how fast you're going ... magnetic field strength has a measurement too it is Gauss.

Now for non metric users (those who are in love with the should-be-dead-by-now imperial system (which is mostly the USA and PommieLand)) I'll explain something basic first a meter is a standard measurement, smaller units are millimeters and converting them is done by thousand. I know this is shocking to people who deal in inches because they'll never have heard of a thousandth of an inch being called a milliInch. (not to mention multiplying by 10 seems difficult for lovers of Imperial)

So how strong is a gauss?

Thats a good place to start, so from a quick google we find this:

refrigerator magnet is 100 gauss, a strong refrigerator magnet. The typical strength of the Earth's magnetic field at its surface is around a half a gauss. So those are everyday units of magnetic fields.

So basically from this and the above table you could reasonably expect that if you sat a fridge magnet on top of your watch which was not marked with the U symbol shown above then it would be likely to be effected by that magnet.

If however yours was type 1 then as they say "A magnetic resistant watch almost always maintains its performance when placed at 5 cm from magnetic field generating devices of everyday life." This should leave you to be comfortable that unless you've sat a fridge magnet on top of your watch then there should be no effect and you can look elsewhere for reasons why your watch is not running on time. My first advice would be that you look at the actual specs for the movement, which are often a few minutes per day. If its an automatic perhaps you should just wear it, as it was designed to be worn.

But what about my phone?

yes, indeed phones can give you a magnetic field, this is usually measured in milligauss. Indeed if you dig around you'll find (on a now gone site, but you can find it on the wayback machine) that (in 2003) a common phone produced about 20 milligauss. For the maths challenged thats pretty small. 100 gauss is 100,000 milligauss and so 20 milligauss is literally nothing for a watch.

So basically you can stop worrying that your phone on the dresser beside your watch has magnetised your phone, and pretty much unless you are a technician working on CAT scanners you can rest easy (they'll probably already be resting easy because they'll know they shouldn't wear a watch) and give up that plan to buy a degaussing tool from eBay (which will probably result in your magnetising your watch anyway because you don't know how to use it).

Leave this one to the watch sub cult of King Wang

Wednesday, 13 January 2021

Making NATO work better for me (and maybe you)

I've had a couple of watches with a NATO strap now and while I would like to like it, I'm afraid that I just don't like the unnecessary thickness under the watch. This is more pronounced with a slim watch on a slim wrist. 

Now its worth mentioning that the very design of the NATO places two thicknesses of strap under your wrist, one is completely enough and the other as a keeper is only really needed if you have a band too small for the watch and there is concern of the watch slipping off when you're taking it off. If you get the right size for your lug width then it won't.

Remove the Appendix

The solution often suggested on the internet is to cut off the (vestigial) keeper. This surgery looked painless enough, so I did it.

which has now made only a single pass of fabric under the watch and still holds the watch firmly.

My next concern was that the cut (and heat sealed carefully with my soldering iron) would be a slight skin irritant (because its rough), but this has proven not to be an issue because the spring bars keep it away from the skin.

As it happens I like to wear my straps "buckle down" or "Grand Seiko" (GS) style, because it is easier to control the keeps the tongue of the buckle facing me and its easier to fit, as well it keeps outside of the watch looking smoother.

The watch can also then sit on my desk easier too

... although now with this band I feel I no longer need to take the watch off when using a computer at my desk.

If you do this yourself I recommend that you use a long sharp blade (such as a box cutter with a fresh blade) and 

  1. clamp the strap down by the end (away from the buckle)
  2. pull the keeper back and keep tension on it (folding it back against the stitch point)
  3. cutting just above the last row of stitching removing the keeper strap
  4. seal with a hot tip (I don't recommend flame)
A quick and dirty vidoe

So now it looks like this, clean on the back:

and the clutter of the strap on the inside (rather than both sides as before) ... where its less likely to catch on things.

and note that the watch is now sitting much nicer.

There is still of course one layer of fabric between me and the watch, and since this is a work watch (yard and other sweaty work) that may just help to keep the watch (my SNK805, which isn't highly waterproof) cleaner and less gunk infested.

 voilla ... win win

PS: this is actually almost a Bond pattern strap now, with the removal of the keeper and the almost correct Bond pattern (oh and no Bond ever war a NATO).

Tuesday, 5 January 2021

Watch Gunk

 One of the old sayings is "out of sight out of mind" and this really applies to almost everything, especially gunk that gets into places you almost never see.

For one reason or another I've always had watches which allow me to see between the strap / band / bracelet and the watch. I've always avoided bracelets which have had covers such as this:

and yes, that's my watch and my bracelet ... but that's a subject for another post. Instead I prefer bracelets like this:

which are more open and to me honest in what they are, not trying to pretend to be something more and give the impress that the bracelet and watch are a single thing.

This is also important because gunk gets in to crevices and forms a film and starts to attack stuff (like metal, like seals ... this is an excellent example from Hodinkee

Festy is it not?

Now my Garmin training watch is something a bit like that, but I have to change the battery every few months so I always have opportunity to clean it, however it does get like this which can be seen when you pull the silicon cover off:


while not as festy as the watch above from Hodinkee its still hardly hygenic.

Now if you're the kind of person who never washes then this is all probably de-rigueur for you, but that's probably not most of us.

That's why I like to have a watch band that makes it easy to keep clean in my daily wear.

indeed you can see this bracelet even has tool-less spring bars and my watch has drilled lugs (very nice) making springbar removal even easier.

Heck even my old faithful has this style of easy to keep clean bracelet with no gunk catchers.

So for tips on how to clean your watch (its pretty simple really) you may as well pop over to the Hodinkee site that I poached that image from and have a quick read.

Lastly as I said at the start this sort of gunk gets into and indeed grows in places like you wouldn't believe ... have a look inside a typical rotating head toothbrush ... after I found this I put mine in a small jar of alcohol (vodka) every day (I keep a small jar by the sink).

Hopefully you can avoid one more place of gunk in your life now.

Monday, 4 January 2021

gaining weight

 I've never liked heavy watches and while I accept that for some specific roles a watch is a tool and that tool needs to be sturdy, very few of us actually need (dunno how many want) massive 300meter dive watches.

So I thought I'd explore how porky modern watches have become with this assortment

The SNK805 tips the scales at 61.5g

yet my beautiful 1965 Sportsman dress watch a mere 39g

Moving on to the more modern SPRE's with a metal band tips the scales at 123.5g (and this isn't my heaviest bracelet)

while its sibling in green with leather straps a much lighter (but still hefty) 71.3g

while my much more elderly 1979 model Sports 100 screw down crown semi-diver (which has been diving a bit) is 80.9g

which is pretty darn close (9g) to the SRPE with light weight leather pants on.

So to my mind watches are getting chunkier and heavier and (as I showed earlier) thicker. 

The thicker a watch is, the further out from the wrist it sits and the more you notice its weight.

I have no idea why this trend is, all I can think is that everyone is starting to just follow the fashion started by Rolex; making things bigger.  Sadly the Rolex classics (such as the Goldfinger Bond or the Col Kurtz Rolexes) are actually not as thick and chunky ... I have no idea why everyone is after these bricks, are they compensating?

Currently the watches I have which feel most comfortable to wear are the Sportsman, the SNK805 and most comfortable and balanced of all is the Sports 100.