well rust indicated iron content,steel came in the early/mid 1800's.....so the axe is dated from 1850's down,also if there was a mark on the axe head then it would of been from the smith or country it came from "example- some early axe heads pre-dating the American Rev has the Crown/royal emblem on one side",..
But by all means DO NOT CLEAN IT WITH CLR OR LIMEAWAY,or any other rust inihibitor,...
USE ELECTROLISIS - A 12volt,2amp batt charger should work fine - Calcium carb aka -TUMS crushed,with a tea spoon of salt and 3 tea spoons of baking soda.,.also add a small amount of Hydro peroxide,...
JUST REMEMBER TO ATTACH THE NEGITIVE END TO THE IRON OBJECT,AND THEN THE POSITIVE TO A STAINLESS STEEL FORK/KNIFE/SPoon and DO NOT LET THE 2 OBJECTS OR THE CLAMPS TO TOUCH -that would cause a fire or injure-,also make sure all the ingredents and items are in your plastic container before turning on the charger...
wait and watch the process for 5 mins,and if OK then let it go for longer - a object that large or has a heavy iron denseity will take a few to finish to where you could make out a smithy mark,also it perserves the item for the future!!!!!...
can ya post a pic?...