Thought i would answer a question about what one should do with a axe or hatchet that has rust on it.
my short answer is that rust is always hiding the true condition of the tool and it never hurts to just give it a vinegar bath and see what you have. the more rust the greater the chance there is a true defect that can effect the soundness of the tool.
below, i just finished hanging a double bit no name that had very good temper and quality of steel. when purchased with a lot of axes in an auction. this head had a fair amount of rust and i was not sure of its true state. after a vinegar bath, i found it worthy of hanging and will make a perfectly good splitter. and i would have no issue felling a tree with this one too.
the main issue i wish to stress is that as long as it is sound a tool then it should be used.
even if one feels that it should be relegated to a specific or limited purpose.
there are two categories of obtaining axe heads for this answer: 1 = purchased & 2 =inherited/given
1 = when purchased i always select those heads that are visually very sound, so the faults are very much at minimum. this includes minimal rust.
2 = there are times when i purchase an axe lot (multiple axes/hatchets sold as one unit) and in this there are sometimes one or two that are questionable. also when given or restoring there are heads in all sorts of conditions. the key for all of these is to never be discouraged as to proceed at least with the first step of any recondition and that is the vinegar bath. i never try to predict what the condition of the metal below the rust is until i have finished the bath.
no matter what the state, i do this because it reveals the introduction of the history of the tool.
i am a bit fan of history!!!
in a way it is like reading the introduction of a book or the cover of a magazine (with all the articles that lie inside). i am positive that i get over geeked up about it but the reveal from the bath is like tallying up the numbers on a lottery card. will there be a winner? the chances here are better than any lottery.
before i go any further i will say that the next writings are about i look for in the reveal. i am not a professional with detailing guidelines that dictate whether or not a few measurement will determine the useability of the tool. i have a few pounds of common sense that give me the ability to judge what is workable and more important to what degree of workability.
there are individuals whom will only use the pristine and i agree that if i were bush crafting or in a survival mode. i would also want the most sound tool in my arsenal for those situations, but here i am talking about something different.
when examined i am most concerned for cracks, craters and mushrooming. cracks, craters and mushrooming are positively a NO go. poxing is almost alway ok in my book. poxing is usually more of a surface blemish. and even though i personally don't mind the rust poxing i do insist that it should not interfere with a smooth, pox free cutting edge. with a little filing i can obtain a nice smooth cutting edge.