I am in contact with RECTA, the Swiss Compass company. They do not have a true 'button compass' , but have a few of the small units similar to the Silva/Suunto/Brunton zipper pull sized units. They explained that even high quality liquid units may develop bubbles. This is due to altitude changes and shouldn't affect accuracy. I gave up on Brunton. If they won't provide an advertised product Ill find other suppliers- for all my needs.

>>They explained that even high quality liquid units may develop bubbles. This is due to altitude changes and shouldn't affect accuracy.<<<br><br>Well, yes, they do say that, but you can sort of tell.<br><br>Obviously, if the case of the compass expands further/faster than the liquid inside for whatever reason (pressure, temperature), then you can get a vacuum bubble inside. These are usually pretty tiny, and tend to disappear if you warm the compass, or shake it. Many of the better units have a diaphragm of some sort, sometimes the whole bottom surface of the capsule is a diaphragm, that's designed to flex a bit and is intended to prevent the problem. Intended.<br><br>There’s another failure mode, though, and I’ve lost maybe 4 compasses to it over the decades. This is when there’s some tiny leakage at the seal/seam, and either air is getting in, or the liquid is sublimating or insensibly leaking out, or both. In this case, it starts out the same, but shaking and warming have little effect on the bubble, and over time it just gets larger and larger. This can effect the accuracy of the compass, especially those with a dial instead of a needle, as gas bubbles can get trapped underneath, and eventually, only part of the dial or needle is immersed- not good. Large marine compasses can be drained and refilled, but “recreational” compasses like the ones we’re talking about just hit the trash can. That’s what’s happened to two Suns, one Silva (a since-discontinued wrist model), and one Tekna that I’ve owned. <br>

Presumedlost : Without question those air bubbles can alter accuracy IMHE. I smear a thin layer of " GE Silicone II " on the seam of all compasses to prevent air intrusion. This has been successful so far, but time will tell.

Neanderthal,<br><br>Thanks for the tip; I may consider it. How old is the oldest compass that you've done that to?<br><br>Shame we have to modify our manufactured articles to make them work properly, but that GE Silicon II is amazingly versatile stuff. We used to slip sections of plastic soda straws over wire splices and squirt the stuff in to water/corrosion proof the splice, on boats or boat trailers.<br><br>When I was a kid I had an old brass bearing compass, dry, with a needle lock ( a little brass fork on a cam that lifted the needle off the bearing a few thousandths of an inch and pressed it against the crystal) and it actually worked rather well. With a little practice you could use the lock dampen the swinging needle pretty easily, and you could sight on a target, gently lock the needle with your eye still on the target, and then read the bearing as a separate operation, sort of like using a sextant. It may have been more primitive than liquid filled compasses, but I couldn’t see any lateral movement of the needle at all when it was lifted, and I’m not sure that it wasn’t more accurate and easier than trying to both aim at a distant object and read the bearing in one operation. Also, with the needle locked, it could be transported with no bearing wear at all, and little worry about damage.<br><br>Liquid filled compasses are great at the helm of a boat, in a car, or on your wrist.. but we might just have over-applied the tech when it comes to taking bearings.<br>

PRESUMEDLOST : Although some of my compasses are vintage, I've only used the Silicone II for a little over a year. I assume that was the point of the question, As you, I had one of those compasses wih the machanical dampener years ago, and I totally agree with your assessment.

I should have clarified my statement. Obviously mechanical failures eventually end in uselessness. I have a 27y/o Silva Ranger model that will develop a minute bubble in cold or high altitude. it has always returned to normal with warming. It's accuracy is still excellent. Using a compass implies walking out is a better option than waiting for rescue. This may indeed be correct in some situations. I have concluded, for my own needs, to get the best compass'. I have my old ranger, a Silva matchcase combo and a Recta army unit. Im still looking for the smallest, liquid damped unit available for pocket kits.Compasses are like guns and knives: only accurate and sharp ones are interesting.

i use silva wrist models for a long time. never had bubbels troubel befor in those, but it did happened in a button silva after flight.<br>generally, the only model i know that is 100% relaibel is the heavy - duty army compass: it's a massive, most acuret 350 grams - much to heavy for a bagpack.<br>i suppose a good wrist silva, with a magnifed glass and measuring side marks, is the best. it wont give u the most acuret azimut - u'll miss a degree or two, but anyway, u alwayes follow tophografy & map and mostly using it to maintain direction. bubbels should'nt effect this featuar.<br>button campuses diverse: some filled with oil, or any other light solutions. filling flude qulity effects bubbels (and price).<br>anyway, if you break your main navagation compass and get to backup, all u can use it for is general direction only - u hardely can keep azimuth or re-azimuth with a butten.<br>a silva finger compass can do a better job: and, u can alwayes use your watch or the sun to verefay and get general estimation. (getting down a mounten during dark is a good recipy for troubels, and might be fatal: only night move is in desert conditions - and deserts r low, so, no bubbels....)

>>I have concluded, for my own needs, to get the best compass'... still looking for the smallest, liquid damped unit available for pocket kits.Compasses are like guns and knives: only accurate and sharp ones are interesting.<<<br><br>If I might make a suggestion- I’m sort of surprised that the compass I carry most often is an old "Silva Model 27 Landmark", which is NOT the same as the new “Silva Landmark” (which is much larger), but seems to be the same as the new "Brunton 27LU Trooper". Pretty hard to find, I’m afraid. The thing is, this is a mirror-sighting compass that looks in the pictures to be similar to a Ranger, but it’s much, much smaller- not much larger than a matchbook.<br><br>I know you’re not fond of Brunton, but this is the only compass I know of this type in this size (besides, it’s really a Silva, and the new Silvas are really Suunto…). There’s a picture at:<br><br>http://www.freshtracksmaps.com/com-backpack.htm<br><br>check out the dimensions- you can’t tell from the picture. It’s only 2.3 inches long. It’s much smaller than any similar unit I’ve seen.<br><br>With 5 degree graduations and no declination setting, you’re not going to use it to call in an artillery strike- on the other hand, it works just fine for 95 + percent of land navigation. It’s capable of map work, bearings, and orienteering, and it can also be opened all the way and pinned to clothing for constant reference. <br><br>I have other more accurate compasses I take with me when I expect serious use, and I have much smaller compasses for emergencies only, but this is so useful for it’s tiny size that it’s the one that I pack on every trip where I don’t really expect to need a compass, and because of that it’s been carried much further than any other compass I own. While not small enough for the tiniest pocket survival kits, it’s small, light and cheap enough to stash for any larger kit. I’ve even carried and used it in the city. Not the most accurate, or the smallest, but it might be the most versatile compass I own.<br>

is any compass that is smaller than a quarter anway going to do much more than tell you (generally) which way magnetic north is?<br>If not then why should one go with a liquid one over a regular needle compass?

I think Chris is the one saying he’s looking for the smallest liquid-filled.<br><br>I do agree that the main use of compasses in this size is just staying oriented- being able to pick a general direction and not going in circles.<br><br>The classic objection to dry compasses is that they take too long to settle down, and that does seem to be less of a problem the smaller they get. My only problem with them is that, in the half-inch or so size range, they seem to come in just two varieties – unbelievably cheap (party favor quality- if you order 10, two have already had the needles fall off) or unbelievably expensive (Brit/NATO versions at $35 each). I'd be glad to learn about some happy mediums.<br>