HOW TO...CLEAN BRASS
This page collects together useful knowledge and tips for the cleaning and preservation of brass items recovered from the sea. Most of the knowledge has been acquired through years of trial-and-error and experimentation.
2..The Acid treatment
Having raised your item from the seabed, the first job is to declare
the item to the Receiver of Wreck in an attempt to establish ownership of
the item. This step should be observed for all items raised from wreck. Items
found lying on the seabed which are not obviously from a wreck need not be declared.
Declaring an item will simply require you to fill in a form describing the object
and the circumstances of its recovery. You will be contacted by the Receiver to
acknowledge your droit with a few days, and will then have to wait until the ownership of the
item has been established. This wait could be up to a year in length, so is an
ideal oppurtunity to pre-soak your item in water as described
in the 'Initial preparation' section below.
Having received legal title to the item, the next job is to soak your
artefact in fresh water for as long as possible. This will allow the salts
to soak out of the item and keep any marine growth from hardening too much.
Ideally, brass should be soaked in decreasingly saline solutions for anything
up to a couple of years before moving on to the next step.
Fine - That's the 'official' method, but in practise, I have found that
skipping the 'soaking' stage doesn't affect the final result.
What is important during preparation is to carefully remove any marine growth
that can be shifted without damaging the surface finish of the artefact. Also try
to remove as much iron as possible, as this tends to neutralise the acid, shortening
the life of your acid bath. I use a blunt screwdriver as a 'chisel' and pick away at
the lumps of iron concretion without damaging the surface of the artefact. On portholes,
pay particular attention to removing remains of the iron nuts, bolts and rivets, which
were used to fasten the porthole. Also remove the remains of the iron deadlight and the
deadlight hinge pin as well as the sealing gasket which sits between the porthole flange
and the ships hull.
Porthole after raising
At this stage, you should obtain two containers big enough to hold your artefact. These
should be capable of being filled with liquid to completely cover your artefact. Suggestions
are: The base of a water butt, the base of a plastic chemical drum/barrel, cold water tank from
your loft (don't use your current one!), central heating cistern etc.
It is important that the container is big enough to hold the artefact, but not too big that
you'll need gallons of liquid to completely cover it.
It may be possible to dis-assemble your artefact to make it easier to deal with. A good
example would be removing a porthole door from its backplate. Use a hammer and a punch to carefully
remove the brass hinge pin, and loosen the dogs to free the door. This may have to wait until the
first couple of dips in the acid to loosen things up. It is important to remove any copper or lead
items from your artefact, as these will result in an electrolitic reaction, resulting in the
brass being copper or lead coated
You'll need some acid. I recommend getting hold of a gallon of 'Hiltons Spirit of Salts'.
This is approx 30% diluted Hydrochloric Acid, and is about as strong as you can buy (it smokes
when you remove the lid!) This needs to be diluted to about 10% before use. Alternatives (in
order of affectiveness) are 'Brick Acid' (from builders merchant), patio cleaner, limescale
remover, vinegar, Coca Cola.
You'll need some 'tools'. I recommend a scrubbing brush, nail brush and scotchbrite
pads (green scoury pads for washing dishes). An old toothbrush is handy for small fiddly items.
The Acid treatment
Dilute your acid with tap water until it is approx 10% strength (always add the acid to the
water, not water to acid). Hot water can be used which
will greatly speed-up the cleaning process. Ensure that your acid bath is in a well ventillated
space before filling with enough diluted acid to completely cover the artefact. Add the
artefact to the acid bath and stand back! It should bubble and foam, and give off poisonous fumes
which maike you choke (burning your lungs away basically) - this is normal! It's at this time that
you regret not doing this outdoors as the smell of rotten eggs and the site of peeling wallpaper
leaves a lot to be desired!
While this is going on, fill your second container with enough tap water to competely cover the
After about 10 minutes in the acid, pull your item from the acid bath (letting as much acid as
possible drain back into the acid bath) and completely immerse in the water bath. You can use
rubber gloves for this, or use a wooden 'stick' to hook your item. If you use your fingers, be
sure to dip them in the water bath pronto :-)
Use the scrubbing brush and nail brush to scrub the artefact, removing as much of the loose
material as you can. Don't worry about getting things shiny at this stage - there's a lot more
work to do before we get to that stage. If possible, try to take as much of the artefact to bits
as is possible.
Repeat Acid/Water cyles until the artefact shows no signs of 'fizzing' in the acid bath. Don't
worry if it doesn't seem 'clean' yet. The acid is purely removing the calcium based deposits on
the brass, and won't remove old paint, iron, gaskets etc. Don't leave your prize artefact in the acid
for more than a day or so....or it will eventually dissolve!
Having satisfied yourself the acid is doing no further good, remove your item from the water
bath and drain it, replacing it with fresh tap water. At this stage it is possible to leave your
artefact completely immersed in the water bath. Do not under any circumstances, leave it out in the
open air, or partly immerse it in the water bath, Doing so will result in your prized artefact
turing bright green and destroying the surface finish. Leaving it sticking out of the acid bath
or water bath will generate a green tide-line on the item, which is very hard to remove later.
Break the artefact down into its constituent parts such as removing porthole hinge pins to seperate
doors from frames, remove dogs (turnbuckles) from their threads (it may be necessary to drill out a
brass pin at the top of the thread which prevents the dog being fully unscrewed)
Using the scotchbrite pad, scrub the artefact until it becomes a yellow shiny brass colour. This stage
can take may hours. You'll get through a couple of pads on a single porthole. The scotchbrite is a
mild abrasive and will lightly scratch any polished surfaces. You can use scotchbrite in conjunction with
a cream cleaner such as jiff etc or use steel wool, brillo pads. Other options for cleaning at this stage are:
i)....Do nothing. Some items look better with a dull finish
ii)...Use progressively finer pieces of wet-and-dry sandpaper to produce a mirror-like finish
iii)..Use a wire brush in a drill to get the item cleaner. Beware - this is a harsh technique
which will leave the item with a permanent 'brushed' finish
iv)...Use a nylon brush in a drill to get the item cleaner. This is a less harsh technique than
the wire brush, and the 'bushing' can be polished out with scotchbrite and brasso.
v)....Use a shot blaster/bead blaster. This can get the item very clean, very quickly, but will
leave it with a permanent 'satin' type sheen which will dull over time giving a very dark appearance.
Porthole after being wire bushed - dull finish
Having 'cleaned' the item with scotchbrite etc, you'll be left with a technically 'clean' piece of
brass which is brassy coloured.....but dull. For polished surfaces, I use a buffing wheel either attached
to a bench grinder or a fast drill. Used in conjunction with progressively finer grades of buffing soap,
mirrored finished can easily be acheived. Beware that some items look more 'authentic' without being buffed.
To finish the item, I tend to use brasso (duraglit) to provide the final
finish which will leave your item very shiny. Other options include using baking soda as a mild abrasive or
cigarette ash mixed in petroleum gel (as a finishing compound)
If you wish to retain this 'gleaming' finish, it will be necessary
to laquer the item before it tarnishes. My own tried and tested technique for this is:
i)....Having polished the item with brasso, wash it with fairy liquid in the bath. Be sure
to wash it thoroughly, as we need to remove all traces of polish etc. Rub the fairy liquid into all
the cracks and crevices and ensure that all surfaces are washed. You'll be amazed at how much 'cleaner'
the item gets at this stage.
ii)...Rinse the item in the bath or shower. Remove all traces of detergent. Be careful not
to handle the item with bare hands at this time.
iii)..Dry the item with a clean towel. Do not handle the item with bare hands.
iv)...Quickly 'paint' the item with a good quality laquer. Only apply one coat and do it swiftly.
The item will be dry within minutes and can be handled after an hour.
So far, none of my laquered items are showing any signs of tarnishing beneath the laquer. It does
save having to polish them!
If, on the other hand, you wish to 'tarnish' your item to provide that time-aged 'patina' look, spray it with a weak solution of
vinegar and leave for a few hours before rinsing off in tap water.
Porthole after being buffed, polished and laquered
A useful tip for cleaning shell cases, is to avoid the use of acid, as this can leave slight 'water marks' on the
surface of the brass which mar the final appearance on the shell case. Instead, put the shell case into the freezer for a couple of days. Boil enough water
to fill the shell, then pour the boiling water into the shell case (having removed it from the freezer). The
expansion and contraction of the brass case will result in most of the calcium growth/barnacles literally falling
off before your eyes. Then clean it in the 'normal' manner using scotchbrite pads etc. Stubborn deposits can be
removed by tapping them with a blunt item (plastic handle of screwdriver etc). As the case was polished when
it went into the sea, most of the growth on the case should just fall off. Do be careful not to hit the detonator in the bottom
of the case. It should be safe, having already been fired, but you never know!