Cold temperatures and knives

tarsier · Apr 10, 2002

I live in a climate that has both extremes - hot, humid summers and cold winters. There are always a lot of threads on BF and the Usenet rec.knives newsgroup that discuss the rust-resistance of various steels in damp conditions.

However, after searching the archives, I have not found much corresponding information on how knives perform in cold temperatures. I am interested in knowing whether there are any effects on steel brittleness and how the effects might vary among different types of steel. I would like to know what to expect in an emergency.

Also, I always keep a folder in an outer coat pocket for easy accessibility and have never had a problem. Still, I'm curious to know if there is a lubricant for folders that would be appropriate for cold temperatures and whether there is an effect on locking mechanisms.

I realize that this is a peculiar question for the spring time, but maybe folks in the southern hemisphere will appreciate it...

Thanks.

Cliff Stamp · Apr 11, 2002

Knives will lose wear resistance as it gets hot, and will lose durability when it gets cold. However hot and cold by knife stantards is a bit more than hot and cold by our standards. I have done a lot of work with chopping blades when it was below zero and never saw on average a large difference in the durability.

If you had a knife that was just durable enough at room temperature and you went at at -10 or so you would have problems, but in general most knives are overbuilt to handle accidental high stresses. Remember that while the change from room temperature to subzero seems like a large change to us, on the absolute temperature scale this is only a change of a small percent.

I have also experimented with knives at really temperures, far below what any person can tolerate, the results are not as extreme as I would have guessed :

http://www.bladeforums.com/forums/showthread.php?s=&threadid=161460

-Cliff

m · Apr 11, 2002

As far as good lubricants for cold weather go, I believe Chuck Taylor did a test in Alaska several years back to see how different firearm action types and different lubes did at -65F. Remoil looked the best in the tests if I remember correctly.

tarsier · Apr 11, 2002

Thanks guys, good info. Cliff, that was quite an interesting thread reference. I had missed that one.

budrichard · Apr 12, 2002

The only time you would have a problem is if the steel in the blade had a high NDTT(Null Ductility Transition Temperature), in short above the NDTT a small crack or defect will not propigate catastrophicaly but below the NDTT it will and you will get what is called 'brittle fracture'. Temperatures that are 'cold' to you, present no problems to modern properly heat treated steels. Note, I am not talking about cast iron or other materials where Fe and alloying elements like Chromium are not the major constituents. Cast iron parts can fail in 'brittle fracture' at low temps which is why you need to be careful below 0 degrees F when working on cast parts. I think sometimes people confuse cast iron with steel.- Dick

Blade Santa Cruz · Apr 12, 2002

As was previously mentioned, we're rather fragile creatures and the temperature variations over the ranges where our survival is possible isn't much to a piece of steel. Lubricants become much more important than steel varieties, as does a proper design. For example, a Spyderco Military, which has a large opening hole and can be operated with heavy gloves on, makes life a lot easier for a user in a cold climate.

I'm always amused by people who worry about properties dropping off at high temperatures. However this may be a concern to you the next time you're exploring the surface of Mercury.

Alarion · Apr 15, 2002

The safest way to go with lubricants at low temps is not which one to use but how much to use.
Put very little if any lubricant if expected temperatures are deeply freezing, as it can get frozen and lock your knife.
A molecule-thin veil is all you get. At worst, leave the teflon washers do their job dry.
Carrying the knife on your person, obviously, greatly reduces freezing problems.

Blade Santa Cruz · Apr 16, 2002

Alarion is right, the only thing you need to worry about is that you use as little lubricant as possible. In fact, if you could remove all lubricant, the knife would still work well. As for the steel itself, it wouldn't care very much if it was at room temperature or 400F below zero.