I would like to echo liamnolan's comment - this is a very useful document, and was created with detectorists in mind:
This guide is aimed at finders, and in particular metal-detectorists, who find and collect archaeological objects. It provides straightforward information on how to care for and record finds to ensure their long-term survival and to capture useful information about their discovery. This guide shares some conservation techniques that we hope will prove useful. However, it does not remove the need to consult with specialists, such as a Finds Liaison Officer (FLO), museum curator or professional conservator in cases where you are unsure of an object’s historical significance or its condition presents difficulties, nor does it remove the need to offer all finds for recording with the Portable Antiquities Scheme (PAS).
The document is only 20 pages but includes sections on cleaning and preserving finds. There is advice on identifying metals (gold, silver, copper alloy, iron, pewter, lead), which then helps in deciding how to clean and preserve artefacts made from them. There is also advice for non-metallic finds too.
Regarding cleaning, there is very interesting advice on what products to use and, just as importantly, what
not to use. It must be very easy to destroy the historcal value of an item, if care and consideration is not given to the immediate
and longer term effects of certain cleaning chemicals! For example:
Before cleaning or washing, it is best to report all finds to the local FLO. This enables a better understanding of the object, and ensures it can be recorded before any changes are made to the find which might result in information being lost. Possible Treasure finds should be reported uncleaned: inappropriate cleaning may reduce the commercial as well as historical value of the find, as indicated in the Treasure Act Code of Practice.
As a newbie to detecting, I cannot help feeling this document ranks very highly amongst those that are a 'must read' for all UK detectorists new to the hobby.