Identify dangerous munitions
General rule is if in any doubt whatever, leave alone. Lots of munitions from all periods on south coast of England. Many are recent losses from testing – can be high explosive and potentially deadly. Basically, if still paint on it don’t even think of touching it. Older stuff can be very bad too. Some explosives weaken with age, others get more unstable. Again, not worth the risk. Only safe to tamper with used and empty stuff like brass shell cases. If still has head in it, touch at your peril. If with anyone who brings live munitions up, insist they ditch it asap. If already brought back to shore, little choice but to call authorities (coastguard a good start) and get experts out. Will usually cause a ‘bomb scare’, but better that than someone getting hurt.
Report underwater finds
All wreck material found in the UK must be reported by law to The Receiver of Wreck (see “… Contact Diving Related Bodies”). Includes mundane stuff as well as portholes (you should be so lucky) etc. Remember too any find might be historically important. Official advice is to leave things where they are and report them. There is a Protection of Wrecks Act 1973 – contact Advisory Committee on Historic Wreck Sites (see “… Contact Diving Related Bodies”) for info. Also, read the leaflets from the Receiver of Wreck. Text of these available on this website on the Salvage Law page.
Clean recovered items
Shouldn’t really recover items anyway (see “… Report underwater finds”). In event of weakness, anything brought from seabed going to be encrusted with crud – mud, corrosion, marine growths etc. Easy way to release most of this is acid. Patio/concrete cleaning acid from DIY shops good as usually based on Hydrochloric Acid that dissolves calcium carbonate in shells of barnacles/limpets/worms etc. Always wear strong gloves & goggles when using acid. Soak item for a few minutes then lift out, rinse in fresh water, brush gently with stiff brush and repeat until all crud removed. Wire brushes effective but risk damaging the item. If wire brush used, best if brass wire not steel. Fine steel wool effective on smooth surfaces too, but again risks damaging any fine detailing. Once crud removed, normal metal polish or wadding can bring out metal surface well.
Protect recovered items
Most non-ferrous metal items rarely decay further once removed and cleaned. Brass, aluminium, bronze etc. all stable. Steel rarely worth lifting anyway, and because slightly porous will contain lots of salt deep inside. If just cleaned and dried, often crumbles away to dust over time. Best to seek proper advice and report items like this. If going it alone, common advice is to flush well in fresh water for months to leech out salt. Good method is to leave in toilet cistern as water flushed through often! After a good long time, remove and dry very thoroughly (e.g. several hours in a very cool oven). Finally, often helps preserve surface of steel to coat well in polyurethane varnish.