Which type of steel do you prefer? Carbon? Stainless? Why?

I'm not really looking at the subtleties of different types of carbon steels or different types of stainless or semi-s steels. I'm really asking about that first level of choice.

Reading outdoor forums there are those with real clear preferences to carbon knife blades. I have both types. I lean toward stainless (or "semi-stainless") for the most part. Still, at an early age I noticed how sharp some carbon blades can get.

My carbon steel blade was an Old Hickory butcher knife I bought in college as a cheap blade for digging/cutting plants during a botany class - I planned on it getting beat up with the digging, but it was cheap. I stored it a thick taped-up cardboard tube of all things. I still have the knife and it is still amazingly sharp.

Since then I've pretty much stuck with stainless or semi-s blades, so I didn't have to worry about rust/corrosion.

A few years back I had the finish on my Ritter Mk3 damaged when - without my knowledge - someone in my son's Scout troop washed it, dunked it in a chlorine sanitizing solution, and air-dried it (sigh). I can only imagine what the knife would have looked like if it had been a carbon steel blade.

Carbon by all means. I assert that the preference for stainless is a marketing phenomenon. carbon steel blades from the middle ages are around, and serviceable-rust is just not that big a problem. Stainless is generally harder to sharpen, more brittle, and not amenable to forging. The stainless blades generally available are ground out of steel blamks by soul-less cnc technology in mass numbers. Using carbon steel allows each user to make his own knife out of available scrap material at lower cost and higher quality than is available in the market.

Stainless. For my use (kitchen and small/medium folder/fixed blade) carbon steel offers no advantage. Some people like to romanticize carbon steels, but they are mostly the same group of people who hate modern/foreign things (easily found on bushcraft related forums).

Geez, Ken_, way to stir the pot!

Okay, I'll play.

First level of choice? For me, stainless is the go-to steel for everyday work. I use my knives fairly hard, on a daily basis. The stainless available these days will take and hold an edge that is entirely adequate for what I do. The knives get wet and dirty, and they rinse or wipe off without complications. For the most part, I don't see the value in fussing with carbon steel. The same applies to my kits.

But, with that said:

I have come to respect and appreciate carbon steel in certain types of blades and certain applications.

My Ontario machetes are carbon steel with a baked-on finish. They have already been worked hard, and have held up. I would take them anywhere and know they would see me through. A stainless machete strikes me as too brittle to trust.

When I am teaching someone to sharpen knives, I put a carbon steel Opinel in one hand and a medium grit stone in the other. They can raise an edge quickly, move it around, create a wire edge, even break it off, and learn. It builds confidence very quickly, which is the key; most people give up because they don't succeed quickly enough.

I can never pass up an Old Hickory at a garage sale or secondhand store. I like the old-time look, the decidedly untacticool layout, the proven old designs, and the smokin' edge you can put on them. [Edit: If they're well used, all the better: that is evidence of honest, hard work.]

I also have a few carbon steel shelf queens that I'll use but not abuse. One is a Solingen hunting knife with a quarter-dime-size chip out of the edge that I bought for $2; plenty of steel left for restoration. Another is an antique hunter I have seen pictures of somewhere, takes an incredible edge, bought at a swap meet for $5. The third is a Cold Steel Carbon V folder in the style of the Opinels but with a solid Zytel handle.

There's my take: stainless for most uses, but some specialty items in carbon.

For EDC folders stainless as a class rules. Mine are all in the newer stainless steels -- 154CM-S30V-S35Vn-M390.

OTOH, my fixed blade knives trend toward carbon/non-stainless tool steels -- 1095, O-1 and lately CPM 3V.

Somewhat like this. Certain stainless spark poorly, suck as S30V. So those don't go in my camping kit. Carbon certainly work better for those times. But overall, my EDC is some sort of stainless, since I don't plan on using a firesteel in suburban US.

Just to be very clear, with modern ferrocerium / mischmetal (whatever) "firesteel" the composition of the striking edge doesn't matter. A broken piece of glass works perfectly well.

From my discussion of the matter at http://www.equipped.org/devices28.htm

The artificial flint used for such purposes is similar to the flints used in traditional cigarette lighters, but it is a somewhat harder alloy in order to give off hotter and more long lived sparks. It is comprised of a mixture of metals and rare earth elements, by weight approximately 20% Iron (Fe) with trace amounts, less than 3% each, of Zinc (Zn) and Magnesium (Mg) and the remainder a combination of rare earth elements, 50% of which is Cerium (Ce), the remainder primarily Lanthanum (LLa) and Neodymium (Nd) and trace amounts of some other rare earth elements. These are alloyed at high temperature and then extruded into rods of various diameters. When scraped with a hard, sharp edge a thin layer is scraped off and the resulting friction heats the scrapings up to the point of ignition, giving off an impressive shower of very hot sparks. Note that this scraper doesn't have to be steel, but the edge does have to be hard and sharp enough to scrape with. A broken piece of glass can be very effective, for example. The back edge of many knives works as well as the sharp edge, if it hasn't been eased.

By comparison, natural flint is a very hard quartz mineral, harder than most steels, which when struck on a sharp edge by steel or iron creates small sparks by removing and heating up the softer metal. These sparks are relatively weak and few in number, so making a fire with these requires a fair amount of skill and special tinders. Natural flint is a real pain in the you-know-what to use compared to the man-made variety. Fine for those re-enacting the experiences of the Old West's Mountain Men and the like, but not very practical for us today. Some manner of man-made flint should be part of every survival kit.

I don't seem to be able to go anywhere or do anything without getting sweaty or otherwise wet. I take very good care of my blades and tools, but stainless gives me a safety margin that I appreciate. The extra time spent sharpening them is, for me, time well spent.

People always say stainless is harder to sharpen, but I've never found that to be the case between comparable steels (i.e. no 1095 vs. s90v).

I have a mix of carbon, stainless and semi-stainless/tool-steel blades. For use in the kitchen I have quite a few blades in Aogami Super (ie Hitachi Blue) as well as White #2. These are Japanese high carbon knives hardened to between 62-64 RC. I find that those knives take about as keen an edge as anything I've seen yet. But I also have many kitchen knives in tool steels and powders (ie PM steel). SRS-15 seems to get within a whisker of the sharpness of Blue or White. AEB-L, a stainless made for razors, seems to be on a pretty even footing with the best high carbons. It does seem to me that high tech stainless loses that "fresh-off-the-stone" sharpness faster than carbon but remains usefully sharp much longer. For instance, my Akifusa in SRS-15 can go several months in a pro kitchen between re-sharpenings where my Tojiros in White #2 are lucky to go a couple weeks.

For outdoors-type blades I also have a mix. I really like O1 and D2, but VG-10 also works well (although I don't like VG-10 very well for kitchen knives). Carbon certainly works but I do sometimes wind up with some rusting.