(I'd recommend the books Dating Buttons and Uniform Buttons of the United States by Warren K.
Tice for some good information on button manufacturers and their date ranges.) Often the big problem is being able to identify the buttons we dig.
This is especially true at sites which predate the turn of the 20th century.
Most of these fall into one of several types: one-piece flat buttons, two-piece buttons, pewter buttons, or tombac buttons.
Each of these button types requires a different cleaning and preservation method.
Editor's Note: The preservation of finds is every detectorist's responsibility.
Proper cleaning can be an important part of that process, but whatever the method, it should always be accompanied by appropriate caution.
First practice on items of little or no value until you have perfected your technique and are confident that it can be safely employed to good effect on better finds.
Remember, too, that results may not be reversible; and for that and other reasons, many collectors and conservators may prefer that certain items remain uncleaned.
All of us, myself included, have made mistakes in judgment with cleaning methods, but I'd like to share some of the methods and techniques that have worked best for me in the past 20 years of metal detecting. There are millions of these underground, and most folks don't give them a lot of thought. The backs of flat buttons frequently have either a maker's mark (company name) or a quality mark.
Both types of marks on the reverse of buttons are called "backmarks." Quality marks were the manufacturer's way of promoting their product.
Typical quality marks include "Extra Rich," "Rich Gold Color" (or "Colour"), "Treble Gilt," "Best Orange Gilt," or any combination of those words ("Extra Orange Gilt," for example).
While quality marks seldom tell us much, makers' marks can sometimes help to date a site.