Case backspring.

[Hjalmar69]

My Case knife, which I carry often has one minor flaw in my opinion. It has a stainless backspring even though the blades are carbon steel. For how long has this been the case?
It is mostly that I like the look of a backspring with patina.

https://imgur.com/a/N0yXKbr

 

[Will Power]

Been many years as far as I know, at least the whole of this century anyway.

Have to disagree, the insides of knives can get corroded and I prefer a stainless backspring as patina is often uneven anyway on springs due to oil seeping from joints, but each person has their own tastes. Believe I have a Böker Penknife which has stainless blades and carbon backsprings that I find odd....

 

[GaiusJulius]

I feel like carbon backsprings can get more corroded or pitted than one might think, and then sometimes they crack or snap at the weak point. Stainless seems to offer a nice functional upgrade.

 

[kamagong]

Been many years as far as I know, at least the whole of this century anyway.

Have to disagree, the insides of knives can get corroded and I prefer a stainless backspring as patina is often uneven anyway on springs due to oil seeping from joints, but each person has their own tastes. Believe I have a Böker Penknife which has stainless blades and carbon backsprings that I find odd....

Why stop at the backspring? While you're at it, go ahead and use stainless for all the parts that require steel.

 

[Will Power]

Not a bad idea, in the right context and with the right stainless

 

[Obsessed with Edges]

Case has built all their folders with stainless backsprings for quite awhile, in both CV and stainless models. Maybe going back to the 1990s at least.

Although I do like the look of the patina on simple carbon steel springs, I more greatly appreciate the increased reliability and wear resistance of the stainless springs. Less to go wrong there. The pitting caused by corrosion of non-stainless springs causes weak spots leading sometimes to broken springs. It's no mystery why many, many more knives with non-stainless springs have more issues with cracks AND wear by blade tang-on-spring abrasion (resulting in loss of snap and closing pull).

Some of Buck Knives' older 300-series knives made by Camillus had stainless blades (440A) and carbon steel backsprings. As mentioned previously with Boker, that always struck me as kind of strange. I have one of the Buck 307s made that way.