Rust on stainless steel knife?

[marshallkarp]

I used fine grit sandpaper to rub off the surface rust

 

[Jos]

Hello, FYI Stainless steel is protected for corrosion because it has a protective Chromium Oxide coating that is formed by a reaction between the chromium (present in the steel) and the oxygen in the surrounding atmosphere (air, water). Normally, this chromium oxide layer is always present, and it will be restored instantly when damaged as long as there is oxygen around. However, under certain circumstances this oxygen is not plenty available and the layer cannot be formed again to seal the metal: this happens in crevices, narrow gaps where there is less replenishment of oxygen rich water. It happens too in the knife holder.
A special form agressive form of corrosion is caused if chlorides (in the salt water) are present in combination with deficiency of oxygen: pitting corrosion, which occurs mainly in small holes in the surface (pits).
higher quality stainless steels can improve but also the desribed measures are OK.

 

[Michael Folise]

I have had an Aeris Silver Jack knife for three years. This is the same as the Oceanic "Spinner knife". All dives are salt water. The design is interesting. There are two rubber ridges that run on the edge of the handle, otherwise the tang, handle and blade are fully exposed. No place for salt water to hide? All I do is rinse it in the fresh water rinse tank if available, or beach shower if beach diving. When I store it for the season I lightly spray it w/silicon. No rust yet.

 

[fisherdvm]

Had that problem too, someone on SB told me to use petrolateum or petroleum jelly. Worked like a charm. Thanks SB.

 

[diveprof]

I use titanium knives now. For SS, I recommend WD 40 after washing/drying from evey dive.

 

[Nemrod]

Cheap stainless steel rust faster than high quality ones. Just like disposable stainless steel surgical instruments, they are alot cheaper than german made surgical instrument for medicine... but they rust in spots - if left in water for too long.

I find that my inexpensive Scubamax dive knife has spots of rust even after 2 morning dives, even before I rinse them off. Heck, it is a small price to pay for something cheap. A little steelwool will buff it off, but I prefer to leave the rust on and put a little vegetable oil on it. It is kind of like the old fashioned browning that folks use on old flintlock muzzleloaders.

If I lose that knife, it is no great lost...... No one ever look at the knife except myself any how. I think to keep it spotless, I'd have to rinse it after each dive... NOT...

You would not want to rub stainless with steel wool. The steel wool will embed in the pores of the metal and compound your rusting problem.

N

 

[Teamcasa]

All stainless steels are not created equally. Some will rust. Silicone - Good.

 

[Puffer Fish]

You would not want to rub stainless with steel wool. The steel wool will embed in the pores of the metal and compound your rusting problem.

N

Very good.. not a common knowledge piece of information...

 

[Gombessa]

I have a cheap SS knife that stayed fine dive after dive (never used it). One day, I used one of the serrated "crescents" on it to sharpen a pencil before a dive. At the end of the day, I had surface rust right where the knife surface was in contact with the wood/graphite. For $10, I can live with that.

 

[Stu S.]

For rust removal, I use a Scotch Brite pad. Steel wool will apply a slight layer of "tramp iron" over the surface, and it can form a light layer of rust. A good dive knife will use 440C stainless steel or similar. That is a type of steel called martensite, and it contains carbon for hardness and a good edge. It is a special steel, and there is nothing cheap about it. Constant care is the price you pay for using this steel.

Want something that won't rust? That's austenite steel, like a kitchen spoon. Very little carbon in that, and it won't hold much of an edge. Titanium? That's a care-free knife. It will not be as hard or have the edge of a steel knife, but still a good knife.

Of the knives I've had, the 440C stainless Tusa knife was the best. I bought it on eBay cheap, and it honed really sharp. The sheath broke and I lost it over Horseshoe Reef.