how can i keep rust from building up on my blades

[jjhenderson713]

Hi, I'm fairly new to forging and am having issues with my blades rusting alot. It seems like every time I make a knife 1-2 weeks later I will look and see light rust building up on the whole blade... any ideas on how to keep this from happening?

[Buzzkill]

There are several ways to reduce the formation of rust on blades.  If you go with a forged finish, the iron oxide layer formed is different than rust and tends to be somewhat protective against rust.  Finish is also important.  The closer you are to a mirror finish, the more resistant it will be to rusting. Leaving the tempered finish on a blade provides a small amount of rust resistance, but does rub off with use. Bluing, browning, or "pickling" can also produce a rust resistant layer, but it will also rub off in use. The best way in my opinion to keep rust from blades is to wipe them with a thin layer of oil or wax to keep the oxygen away from the steel  and therefore prevent rust.  There are some other coatings, such as powder coating which can provide a more durable layer, but cost can be prohibitive and/or leave an undesirable finish.  You could paint a blade too, but that wouldn't be my choice.

Another thing to keep in mind is that certain liquids or fumes from liquids can cause or speed up the rusting process significantly.  Any strong acid will have this effect.  Hydrochloric (muriatic) Acid fumes reportedly will cause rust formation even 20 feet or more from an open container.  Even the vapor from vinegar can increase rust formation on steel.  Hope that helps.

[C-1ToolSteel]

What Buzzkill said.

I really think your issue is most likely because of a realitively coarse finish. Even a 220 grit finish will rust much more quickly than a polished blade. Learning how to properly finish blades (and buying plenty of sandpaper!) is a very big improvement. It is a good idea to dab a little oil here and there, but you would be amazed at how much more rust resistant steel can be if it is polished.

[Frosty]

Welcome aboard JJ, glad to have you. If you'll put your general location in the header you might be surprised how many of the Iforge gang live within visiting distance. Dito Buzzkill. Buff and a light coat of oil.

Frosty The Lucky.

[Will W.]

As if it needed to be repeated  (maybe just a little more reinforcement) polishing and oiling are the way to go.

You could also clear coat the blade, if you really wanted to I suppose. 

What buzzkill said about the acid reminded me; the acids in food like tomatoes, limes, oranges and onions (I think that was another one) will work a number on a carbon steel kitchen knife. After dealing with foods such as these, always wash the blade, immediately dry it, and hit it with some oil. That will keep the rust at bay. 

[jjhenderson713]

thanks... i have only been using a 220 grit and nothing higher for finishing the blades i suspect that is the problem after reading all your answers. Is there any variety of oil you suggest?

[Will W.]

A bit of a delayed reply, but here goes. 

If its just a camp knife, or a shop knife, or an EDC, etc. literally any oil will do, for the most part. You just want an oxygen and moisture barrier. If its a kitchen knife, you obviously want to only use food grade oils. Olive oil, canola oil, peanut oil, etc.

[OlvinJanoisin]

for oils use wd40, just dug these items from snow (xxxxxxxx cold) when I saw this post.. (saw blade has been on rain for 6 months, other piece 2 months more, snow came week ago..)

These were my test items for rust protection , saw blade other side is uncoated. Please see the difference.

For my 'easy to rust' blades the wooden inner part of sheath seems to protect somehow the blade from rusting(!) , just remember to wipe the blade ALWAYS before sheathing.. And use the knife frequently  

For rust removing put the blade on vinegar for couple of hours, and rust is gone.

[edit] Sorry for bad quality picture, the other test part has only couple of spots of rust, its also blacked on oil.