Conservation of Metal…

Below is a suggested list of tools, these are best to have at hand, before you start…

Wooden picks of various sizes & thickness are needed to be able to successfully clean off corrosions, encrusted dirt etc…  Whilst being able to clean in-between the letters around the coin & for finer cleaning generally, especially around the detailing…

Within this small thesis, you will find all about the common chemicals, that are available to purchase & help conserve the artefacts that are found, with some tips, & do’s & don’ts…. 
Contained within this small paper are the chemicals and their use on metals, for conservation…
There is very little metallurgy information contained within these papers, this is not a comprehensive metallurgy study, the information supplied is solely on the chemicals & their usefulness…

Health & Safety are paramount;

Every chemical purchased, comes with clear health & safety guidelines, along with clear & precise instructions on the chemicals use & the do’s and don’ts, so please read the enclosed instruction carefully & follow the guidelines…  Remember the health & safety officer is always looking at you, in the mirror;


Possible List of tools & Equipment;

Melamine Lap Tray

Wood or Plastic tongs…                                

Wooden Picks               

B.B.Q. wooden picks…

Paintbrush (assortment of sizes) fine haired with no bristle lose, is best…

Parts Brush

Cotton-buds (Q-Tips)

Roll of Highly Absorbent Kitchen Paper

Dental Picks…

Toothbrushes…

Brass brush…

Steel brush…

Fibreglass brush (propelling pencil with steel, brass & fibreglass inserts)…

Goggles & Safety Glasses (with side protection)…

Vapour mask…

Face mask…

Latex, Plastic & Rubber Gloves…

De-ionised water, in a food grade bottle…

Glass & Plastic Containers, of various sizes…

Always follow the Instructions supplied with these chemicals, as the content described here is just a pointer to their use, and what the end result should be…


 

INCRALAC –

Incralac; – This is a volatile & highly flammable compound, & must never be used near a naked flame or a hot lamp !…

Incralac is a lacquer specially designed for use on copper & its many alloys. 

Avoid direct contact with the lacquer, if it splashes onto your skin or into your eyes, rinse thoroughly in clean water & seek immediate medical advice…                                                   Avoid breathing in the fumes & always wear a Vapour Mask, as the vapours are an irritant, & always use in a well ventilated environment…                                                             Incralac is applied after the removal of any corrosion or the corrosion has been stabilised, and applying the Incralac is the final process.

Incralac is a “methyl methacrylate copolymer” which incorporates “Benzotriazole” once applied as a final coating; it provides protection by inhibiting vapours & to absorb ultraviolet light. 

Before applying Incralac the artefact must be dry & completely free of any grease & dirt, if problems occur removing the grease, then the grease can be removed by using a Q-tip, dipped in methylated sprit, & wiped over the artefact, & left to dry…

Once your satisfied that the artefact is dry, you can then carefully & very slowly brush the Incralac over the artefact, a tiny paint brush is best to do this, as you must avoid creating air bubbles.

Once entirely covered, leave to dry, the longer the better as it must be completely dry.


Benzotriazole – (C6H5N3)

Benzotriazole compound is intended for use on copper & its many alloys.

Wear gloves – Wear safety glasses – Avoid inhaling – Do not ingest…

Avoid direct contact, if it splashes onto your skin or into your eyes, rinse thoroughly in clean water & seek immediate medical advice…  Avoid breathing in the fumes & always wear a Vapour Mask, & always use in a well ventilated environment…

This compound acts as a barrier between any corrosion within the metal, & the moisture present in the atmosphere which are, the active ingredients for “Bronze Disease” if done right this stops further outbreaks of Bronze Disease, but will not completely cure the problem, as this process might be necessary to repeat after five odd years…

This is best used for artefacts that are fragile, & where patinas, inlays or other decorations need to be preserved…

The artefact must be dry & completely free of any oil, grease & dirt…

Carefully remove any superficial corrosion, that you can see on the surface…

Once the artefact is prepared & dry, place into a container, then pour enough solution to cover the artefact,  then seal with a tight fitting lid (this not only prevents vapours from escaping, but it prevents the fluid from evaporating) a normal occurrence within the solution is a white cobweb (which might appear) & is nothing to panic about…

After a few days (depending on the size of the artefact) maybe a couple of days to a week soaking in this bath, remove from the container & leave to thoroughly dry, should a white powdery substance appear on the artefact, this is quite normal & nothing to worry about, just carefully brush off with a small parts brush…  

The solution of Benzotriazole can be poured back into its container, to be used again later, when you have finished with it…


E.D.T.A.  –  (Ethylene-Diamine-Tetra-Acetic-Acid)…

E.D.T.A. compound is used in the treatment of lead, tin & pewter, showing signs of surface or dense corrosion…

When handling Lead, always wear gloves & wearing a dust mask is preferable…

When handling Lead, it must be remember that lead is poisonous… Hands should be washed before, during & after handling Lead… Lead should not be inhaled or ingested…

When handling E.D.T.A. always wear gloves, safety glasses & a vapour mask, keep the solution off the skin & out of the eyes, if contact is made then use copious amount of water & seek medical advice… always have a printed copy of the chemical at hand…

The artefact must be dry & completely free of any superficial corrosion from the artefacts surface, & all of the oil, grease & dirt removed…   Once the artefact has been prepared for treatment, then place the artefact into a plastic tub, pouring over the solution sufficient to cover & leave to soak, do not leave this in too long as it might damage the artefact, depending on the surface corrosion five minutes might be long enough, wash the artefact under running water before inspecting to see if most of the surface is clear, if the solution has worked, on the majority of the artefacts surface,  but a few stubborn encrustations remain, then a Q-tip dipped into the E.D.T.A. solution can be used to dab on the stubborn parts, which will soften the compacted corrosion, ready for it to be removed mechanically, with small wooden tooth picks dipped into the E.D.T.A. once satisfied that you have finished, then clean under running water, repeat as necessary until your satisfied with the results…

Once satisfied with the result, leave to dry thoroughly, once dry you can then protect the artefact with a treatment of microcrystalline wax…   Any remaining E.D.T.A. solution can be returned to its original container, for re-using, unless it is cloudy, which is a clear sign that it is no longer fit for purpose, & should be discarded…


Sodium Sesquicarbonate…  (Na2CO3NaHCO32H2O)

This is used to neutralise Hydrochloric Acid & to remove Chlorides.

Ideal compound for the treatment of Corroded Iron or Copper Alloy items, as it does not have any harmful effects on inlays or patination…  Please follow the instructions supplied to make up the solution… Before the object has a bath, it must have the oil, grease, dirt & superficial corrosion removed from its surface…

Once cleaned the item is then placed into a plastic tub with a lid, making sure that the item, is completely covered, by the solution before putting on the lid [by having a tight fitting lid this helps to prevent loss of fluid by evaporation]

Now leave it for a few days, if the fluid has turned blue, dispose of this old fluid & pour a fresh solution, into the tub, repeat this process until no change in the colour occurs…

Depending on the size, or how badly the item is corroded, this might take several weeks (so please be patient)  Once the item has finished its treatment, & your satisfied the process has finished, remove the item from the solution & leave to dry, please make sure it is totally dry, before the next step.

Once completely dry, the next step is to apply a coating of either Incralac or Microcrystalline Wax, these acts as a protective coating, & now the Artefact can be stored or put out on display…

Health & Safety…  Wear either rubber or latex gloves; the latter lets you have more dexterity, with fiddly items…  This product is classified as Non-Hazardous, but ingestion should be avoided, so cleanliness is paramount, & washing your hands after touching the treated item or solution, is best practice… 


Microcrystalline Wax  –  

Microcrystalline Wax should not be ingested…  When handling Microcrystalline Wax always wear gloves, safety glasses, vapour mask, & cover the arms & legs…

Keep the hot wax off the skin & out of the eyes, if contact is made then use copious amount of water, to cool the affected area, without removing any wax stuck to the skin & seek immediate medical advice…  

Have sheets of absorbent paper & a pair of tongs, laid out on a melamine tray…

Microcrystalline Wax is a bi-product of petroleum refining, this semi-synthetic wax can be used to provide protection from moisture vapours, this works well on most metals, & their alloys (lead, copper, iron, silver & their alloys)… Once all of the corrosion has been removed from an object or the artefact has been stabilized, then the use of Microcrystalline Wax is applied as the final stage of preservation…  Before the object is coated, it must have the oil, grease, dirt, superficial corrosion removed from its surface & the artefact must be stabilized…  Microcrystalline Wax is ideally suited to large or small fragile Artefacts…

Once the artefact is prepared, make sure you have sheets of absorbent paper [big enough to lay the artefact on] with a pair of tongs laid out on your tray…

Put enough wax in an old saucepan for the object to be totally submersed & place on the heat, Microcrystalline Wax melts at 800c & is best kept above this on a low heat, when the wax has melted, place the object into the melted wax and watch for the air bubbles to stop, once the air bubbles has ceased remove the artefact from the wax with your tongs and place on the absorbent paper. Any excess wax can be removed from the artefact with a hair drier & gently dabbed off with the absorbent paper…

Pour the remaining melted wax, into a suitable container, as this can be re-used later, or leave in the saucepan & leave to solidified, & when it becomes cool enough, transfer to a suitable container…

At 2000C + the wax will ignite. If this happens “never use water” to extinguish, instead use either CO2, dry powder, foam or a fire blanket (I always have a fire blanket handy as it does not have a shelf life)


In the Field

Please remember that all Metals are complex materials, made up of one or more compounds; and as such any preservation of these Artefacts in the field, should be limited to one of prevention, rather than cure…  Once excavated, Artefacts are best kept separate in self seal polythene bags, maybe with a small bag of desiccating agent [small water absorbing bags found in new electric appliances, and are cost effective to purchase]…   


Other items picked up, whilst out in the field or from exploring dumps, houses etc… Pose a different problem on conservation, for example some bottles might contain “sickness” or a piece of decorated wood is waterlogged, a basic guideline on what to do to help preserve or prevent further decay is explained in other papers, many are simple tasks but with stunning results…

If you’re walking over fields or sticking to footpaths, it’s surprising what people walking their dogs or walking for leisure actually miss, by keeping an eye on the ground these non-metallic objects are there to be found, quite often just a farm worker or walker discarding their rubbish thoughtlessly, a hundred odd years ago, a discarded clay pipe or even a fossil, these might all need cleaning…


WARNING

Bronze Disease

“This is so important, that i have put this in here, as a cautionary note”

If coins are found in damp conditions [most of the coins / artefacts we find fall into this category] even being stored in a damp environment, or were not completely dry, before being stored, they can get the dreaded bronze disease, all though most objects are found with a certain amount of this disease…

Beware; Bronze Disease can be spread to other Coins or Artefacts…

This is a blue or greenish, soft powdery substance which begins in one area and spreads (sometimes no bigger than a pin head) over time the coin / artefact will disintegrate & be destroyed because the process of the disease releases tiny amounts of muriatic or hydrochloric acid which attacks more areas of the diseased object.

Even if you manage to remove it, without treatment it will certainly re-appear after a while.

Treatment: Manually remove as much rot as you can and then place the coin or Artefact in distilled water for 10 to 30 days depending on the size of the afflicted area, changing the water daily.

Then you can place the coin for two hours in an oven at 200° C or 400° F although this may not be necessary (don’t forget that this will darken the coin). Then coat the coin in microcrystalline wax or an equivalent to seal the coin and prevent the rot, coming back straight away, this might need repeating in five or so years, or sometimes earlier (so keep an eye on the coin or artefact, to be able to keep on top of the rot) & if the coin / artefact is to be stored with other items it must be kept in a seal capsulise…