Natalie Ison, Andrew Pearce and Peter Bucke, National Museum of Australia, 16 November 2012
NATALIE ISON: Good afternoon and welcome to this particular talk. My name is Natalie Ison, and this is Andrew Pearce and Peter Bucke. We are all objects conservators here at the National Museum of Australia. I am going to give a bit of an overview of what we are talking about today. We have a variety of products here. We are going to discuss cleaning, particularly shiny silver things, also mentioning trophies and medals as well as cleaning and storage that you can do and that we do at the Museum.
There are three different conservation teams here at the National Museum. We have the objects team; the paper and textiles team; and the large technology team as well. Something very wonderful and important down in the temporary gallery at the moment is that we have moved half of our labs over to Acton to show you what we do. Until 28 January between 11 am and 3 pm every day, at least two of those labs are staffed. So if you would like to come down and have a look at what we do and maybe ask us some questions, in addition to what we are doing today, we can do that.
A quick note to please turn off your mobile phones or turn them onto silent. Because we are filming and recording this presentation, by participating in the question and answer session at the end you are providing consent to be filmed. So if you don’t want to be filmed, just bear that in mind and please don’t participate. I will hand over to Andrew to talk about medals. Thank you.
ANDREW PEARCE: Howdi folks. The first thing we are going to do is talk about treatment of medals at home because I know a lot of people have them. As far as home treatment of medals, try and do as little as possible is the take-home message from my point of view. To illustrate that and to explain where I am coming from, I want to look at a particular small grouping of medals that someone might typically have if they had a family member who was active in World War I. Pretty much everybody in the Allies who turned up in World War I ended up with the 1914-18 campaign medal and the victory medal; distinguished service orders, about 8,000 were given. As far as mentioned in dispatches oak leaves, I am not sure of the numbers but it was quite a common valour medal. This is what that medal grouping looks like. You have the DSO on this side, the 1418 campaign medal in the middle, the Allied victory medal on the end and the oak leaves are usually pinned into the ribbon of the victory medal.
Looking at what can go wrong if people are dealing with medals at home, with the DSO, the white is a proper enamel. The red and green in the centre on the leaves and around the crown are just a lacquer and they are solvent in ethanol, acetone, nail polish remover or whatever else. So if anybody went to clean this and they were using solvent, they can pretty easily completely destroy the middle of the DSO, which is not something you want to do.
The victory medal is a funny one. Even talking to folks who have a lot more experience than me in medals, they don’t actually know what the coating is that has been applied to this. It looks like it’s a bronze medal but it’s not bronze; it has just been minted in copper and then it has had a lacquer layer put over the top. It’s very easy, either through abrasion or scratching or medals banging into each other, to put holes into that lacquer layer. As soon as you get a small hole in the lacquer in a large piece of metal, the exposed area corrodes very quickly. Because you have a hole in the lacquer you can’t clean it off by polishing it. If you start polishing, you just make the thing worse; you increase the size of the hole. So it’s very easy to damage the lacquer on the victory medal, and you can’t undo the damage.
The last one I wanted to cover is the oak leaves. They are a similar alloy but not the same alloy as they use in making Victoria Crosses. They are patinated, which means they are deliberately made to look brown, and they are designed to get darker and darker over time. If you were go through and polish them up and get them looking nice and shiny, you have basically ruined what they are supposed to look like.
The 1914-18 medal in the middle is pretty much silver, and you are unlikely to do anything aside from possibly scratch it, if you attack that. What that does illustrate is that, by not knowing what you are doing, it’s very easy to trash 75 per cent of the items in that medal group. This is just a very tiny example. There are hundreds and hundreds of different sorts of medals. Even in just the Allied side going through World War I and World War II, not even getting to Vietnam and Korea, you’ve got a couple of hundred medals and they all have different metal makeup. Their base metals are different.
The best treatment is to try to prevent the damage in the first place. This is not a medal, it’s just a little christening cup. You can possibly see that it’s purple and blue and quite horrendously tarnished all over. That is purely due to being in a cupboard in storage with timber vapours – rosewood and oak are two that are very bad. Almost all of the modern manufactured timbers – MDF and craft wood - are terrible for metal surfaces and especially things like silver.
We have here a group of medals that have been given to us for the purposes of demonstration, and this is how they are normally stored. They are normally stored in a little wooden box, which is what we would suggest you don’t do. They don’t quite fit; they are all crammed in together. The box is velvet lined. Velvet often also gives off vapours that are damaging to metals. The best thing that you can do for these medals is to stop them banging into each other. That is what is going to cause you more damage and scratching than anything else. If we can lay them down on the table and get some acid free tissue paper, and then one at a time we just wrap each of the medals so that it’s not going to bang into the one next door. It’s not the most elegant solution from the point of view of display but, as a general rule, most people aren’t displaying their medals for a long amount of time. And if you did want to display them, it’s an easy matter to get the paper off. They get individually wrapped up so they are not going to hit each other.
There is a wide range of base metal that has been used for manufacturing medals over the years. Some of it is quite high-grade alloy such as sterling silver. The Victoria Crosses are actually made out of bronze from a pair of old cannons from the Crimean War, I think it was, and they are gradually working their way through. They are nearly at the end of cannon number one and they have been giving them out for a very long time.
But with some of the other medals - there are some Chinese and late war German medals from World War II where the alloys are not terribly high in quality and can be quite problematic.
These all fold up neatly and then, if we want to stop them getting attacked by timber vapours or any other sort of pollutant, the easiest thing to do is to slip them into a zip lock bag. In that way they won’t bang into each other, they won’t get scratched, and any polishing and cleaning that gets really only needs to be done once and the rest of the time they are stored happily. Some of the colours of the medal ribbons are quite light fugitive, the colours. So if they can be stored in the dark, that’s better. If you are going to look after a set of medals, that’s pretty much the best thing you can do with them.
As I was saying, the metal alloy, the plating, the coatings, the lacquers, the patinas, the paint can vary very widely. Even experienced conservators such as ourselves will get in touch with somebody who has a lot more experience on medals before we start doing anything to them. Our advice would be that you get in touch with the Australian Institute for Conservation of Cultural Materials http://www.aiccm.org.au/ and get a specialist conservator to help you out if you need to work on medals beyond what I have just done there. I think that pretty much covers what I wanted to say in the short term so I will hand over to Peter.
PETER BUCKE: Leading on from the storage situation at home and speaking of pollutants and things, one of the most wonderful thing we probably all have in our cupboard at home somewhere is an old silver pot or a trophy. You can see here an example of a silver teapot, some little silver spoons and a little cake tray. And this is your typical sort of trophy that you would find in a club. In the past, I guess what most people do is rely on the good old proprietary products. There is nothing wrong with using these products but it’s what you do with them afterwards. But in a conservation situation with the objects that we look after in a museum, we don’t particularly want to use products like this because what you are actually doing is abrading away the surface. A lot of this stuff is silver plated, so you have a base metal and then you have a very thin plate over the top of it to keep it all nice, glossy and shiny.
It ends up in the cupboard at home and gets dragged out for the tea party. You get out your fancy spoons and say, ‘They are all black and dirty. I have to clean them.’ So out with the polish - rub, rub, rub. After probably 25 tea parties, Mum says, ‘The pot doesn’t look silver any more; it’s gold. I thought I got a silver one. This is not silver; this is silver plated. What have I done to it?’
In a club situation, they have just had a footy game and had the big presentation. The cup gets put out in the bar and you have the bistro running with your fish and chips going, you have the bar going and back in the old days when everyone used to light up and have a smoke, these things would absolutely get covered with grot. Again, with the presentation next year, ‘We have to get the perpetual trophy out. We better clean her up.’ Out with the brasso and the cloth - rub, rub, rub. It’s not a good thing because you are wearing away the plating.
A very simple solution for you to do at home if you just follow some very simple steps is to get a bucket of water and some dishwashing liquid. Look at that - it’s not even radioactive although it looks it. Swirl it up a bit, and we will use this lid here. I should be wearing gloves but I will tell you why it’s not a problem. For this lid, you have a lot of fat, residue and probably tobacco smoke inside a house and it’s been stored in a cupboard in the kitchen. You have fat from the kitchen, maybe a smoking house or off gassing from wooden cupboards et cetera - silver is a great attractant for any pollutants that are in the air. If a pollutant is in the air and it sees silver, it’s like a bee to a flower: ‘I’ll go and sit on that, I’ll destroy it and make it corrode.’
Essentially what you want to do is you want to wash those bad things off it. This is good. Look at that: it’s already starting to clean, but you can see there is quite a bit of dirt on that. It is not just something that you can hit with abrasive polish and think I am doing the job. You might find you can wash it like that and it will turn out quite nice. This cup has been sitting in a club with the exact environment that we have been talking about.
Most importantly, whenever you are doing any of this sort of work, whatever you are using - wash it off. With some of the old pots like the old teapots where Mum has gone in with the Silvo, you always end up with polish residues in all the little crevasses, cracks and turns. The best way to get those out - get them out if you can because they are just sitting there and form a poultice for moisture, and underneath that moisture you get corrosion, pitting and you lose your plating. So you can use a very simple toothbrush going through all the little turns and buckles - in this teapot you have all these little decorative bits around here. That is where you see all that white stuff, which is just going to sit there and be annoying, and you just keep adding to it every time you use products like this. You want to get that off; you want to get a clean surface.
Then you will be left with something that is still fairly tarnished and you think, ‘What am I going to do with that?’ Mum would have got the Silvo out and polish, polish, polish - no, don’t do that. Get yourself a plastic bucket - very important: it must be plastic not a steel bucket - and a piece of aluminium. You can go to the local hardware store and you can pick up aluminium. Make sure there is no coating on it and drop that in the bucket with some warm water. It is as simple as that.
Then you go to the supermarket and you look for washing soda. This is all very grandma, because grandma probably used washing soda to soak her feet in a bath after a heavy day out in the garden. This is bucket chemistry literally: a handful of washing soda in there. What’s going to happen here is I am going to place the lid on the piece of aluminium so that it makes contact with it.
A few little things you need to know when you do this at home as well. Some items like a teapot have large cast handles and things. Sometimes they are hollow and have little holes in them. You want to identify where the holes are and you want to block them off. The best way to do that is a little bit of plasticine or even blue tac. Just block the hole off so you don’t fill it up with water. So this thing is now sitting in contact with the aluminium in the solution of water and the sodium carbonate. You end up with an electrochemical process - I am not a chemist so I don’t know how to explain it exactly. Andrew is a lot better at this and he has a magic board over here which flips and will give you the whole formula.
ANDREW PEARCE: What we are looking at with silver tarnish is actually silver sulphide. It has reacted with sulphur in the environment. We start with 3Ag2S - that’s silver sulphide - and we get a piece of aluminium. What happens is it turns into 6Ag, which is just pure silver, plus Al2S3. What we are doing is we are getting a chemical reaction that is dragging the sulphur off the silver and depositing it onto the piece of aluminium.
PETER BUCKE: Your piece of aluminium will actually - after doing this process quite a bit, you can see the deposit of the product from the actual silver. This takes a fair bit of time to do. You could be sitting there for an hour or so waiting for stuff to happen. But if you look in there and see fizzing happening, you know something is happening. This is a little tip you learn on the way. Now that is already cleaner and you can actually see the original previous polish marks on there. They are actually abrasions. It has actually been abraded by products like this. Occasionally during the process just give it a bit of a rinse-off and a light rub with a T-shirt cotton-type or wool-based material, not synthetic, because they are also absorbent. If you give it a little rub over. This is black so you can’t see - sometimes you can actually see black stuff coming off if you are using a white T-shirt. Then you might say, ‘Oh yes, that’s pretty good’ or ‘no, it needs some more,’ so you bung it back in and make sure it’s in contact with your little coupon of aluminium.
I can show you an example of this one - I just dipped this one in half way. You can see this side is nice and shiny, and the other side still the original look. There were no abrasive cleaners used at all on this. It’s 100 per cent clean and it looks good. If you want to just enhance that slightly more and you are not happy with the finish, there are products available like silver cloths. These are still abrasive but they also have a cleaning agent within them just to help lift off the stuff. This is probably the least abrasive you will ever need.
Once you have done this first process - you have got the dirty silverware out of grandma’s cupboard and it’s now in your care, you may want to go through this process, use a silver cloth, get it all clean. You’ve got rid of all the old Silvo built up inside here, and from then on you only need to do this process very simply.
This is a teapot here. If you look at that closely, that has never ever been cleaned with Silvo or Brasso or any of the other Goddards’ things; it has only ever been cleaned with this method. There are no scratches on it. Therefore the plating that’s on there - this is a teapot my wife and I got for a wedding present. I have been married 35 years and there’s not a scratch on it. So it is all still there. It is a very simple method.
The most important thing to remember between each of your processes is rinse off. Always have your running water there and rinse off. When you have washed it, you can use a little paintbrush or a fine toothbrush to agitate the polish residues that are left in there. You will effectively be doing some abrasion while you are doing it because you are removing it, you are agitating it, you are re-invigorating its solubility and it’s going to spread around and start scratching again. You have only done it once and you will never have to do it again.
Then when you store it, if you don’t want to put it on display and you just want to put it away ready for the next tea party, it is the same deal as what Andrew did with the medals: wrap them up in, say, a washed cotton. Even if it’s an old T-shirt that has been washed a few times and it is well rinsed, you can wrap it up in that. Then you can get these zip lock bags at stationers, you can get one big enough to fit that in, and you can put it in your cupboard. It will be ready for you when your next tea party is up or if you want to put it on display when the family is coming over because it was a wedding present. You want to hide it but then say, ‘They are coming over, where is the teapot? It’s perfectly clean in the cupboard.’ So the family can say, ‘Oh, there’s the lovely teapot we gave you.’ It’s such a simple thing.
Little things like these spoons, again there are issues with souvenir spoons - always try to work out what the product is made out of. This is enamel, so that’s fine in this situation. But if you have some of those modern hand-painted ones or plastic, obviously you are going to run into issues even if you put through your dishwasher or through your normal washing-up liquid. That is about it. It’s very simple. What are we doing next?
ANDREW PEARCE: We are going to touch on some of the things that we would suggest people don’t do.
PETER BUCKE: With the polishing, just to give you an example of that teapot there, you’ve got your base metal, that’s what the pot is made out of it; then it gets plated; then it gets chucked in grandma’s cupboard or in the club; and you get all the dirt and muck all over the top. What we are doing then is old style going along and we are saying, ‘We need to polish it, clean it.’ So we have cleaned that off with our abrasive polish so we are back down to that surface. But while we have done that, we have actually scratched it so we have these pits. Next time comes around, more dirt - polish it again, polish it again, surface becomes thinner. This is all highly exaggerated but this is what happens.
Then eventually after numerous polishes, you start getting down to this surface where you are actually exposing some of the brass. That’s when you see objects that look quite yellow. That is actually the brass you are seeing and no amount of polishing is going to make it silver again. Then eventually you have polished it all away and you are just left with your brass surface. Ideally, get away from the Brasso and the Silvo and get on to something that is less invasive. Do you want to talk about the copper products?
ANDREW PEARCE: A few years ago on an evening when I was sitting at home and bored out of my skull, I had the misfortune to turn on the television and watch Healthy, Wealthy and Wise. Tonia Todman was talking about cleaning brass and copper stuff at home saying, ‘Here is an really easy way to clean brass and copper. You get a lemon, you cut it half, you sprinkle some salt on it, you rub it on your brass and copper things, and they come up all shiny.’ And they do for a while and then they start turning green, because what you are doing is etching the surface of the copper and introducing salt. Copper and salt really don’t like each other.
Again we start getting into the scary chemistry but what’s going on is all of this: we get copper and salt and moisture (Cu plus NaCL plus H2O) and we get copper plus and chlorine minus ions in solution. They form copper chloride (CuCL2), which is green. And then if we add oxygen and more moisture, our oxygen (O2), our moisture with the 4H2O and CuCL2, 3 copper hydroxide (Cu(OH)2, which is also a bluish green. And even better we get this one here - 2HCL (hydrochloric acid), which loves eating copper. So we get 2Cu, 2HCL that is 2CuCL2, same stuff as we add here, plus H2. Hydrogen ions join up nicely with the chloride ions from the salt still in solution and make more HCL. Once you have the chlorine in the alloy, it just keeps on going around in circles. It’s what they call a cyclic corrosion process.
The easiest way to stop that corrosion process, short of doing a full polish and cleaning things out - mechanically remove as much as you can so again toothbrush and soapy water - is get rid of the H2O and the O2. So get it dry and get it out of the air, and that will stop the cyclic corrosion process. The H2 can’t combine with the CL if there is no moisture to provide the H2 supply. These are all electrochemical processes that won’t happen if things aren’t damp.
Polishing things is all well and good, but some things like this piece of industrial equipment, for instance, is not designed as a display piece. If you polished it up to the nth degree and it all looked shiny and bling, it would actually look a bit ridiculous. Our recommendation with something like that - once you’ve got it cleaned just with doing the soapy water to get the residue off – is to try to leave it alone as much as you can.
You will notice that I am wearing gloves. One of the things that copper and brass especially attract like it’s going out of style is fingerprints which etch the surface. We would strongly advise you don’t follow the lemon and salt solution for cleaning things.
You wanted to talk a bit about storage, I think, Peter.
PETER BUCKE: We talked about the plastic bag and tissue paper or a good clean cotton fabric of some sort to wrap your silverware up in if you are going to hide it away in the cupboard. In the Museum we need to get access to our objects frequently. You might say about a lot of museum objects, ‘We have treated them and put them away into storage and we forget about them.’ We don’t. We routinely have to go and inspect all our objects to see what is actually happening. You put them in these micro-environments expecting ‘I’m done, I never have to look after this again’ - wrong. Things still happen even in a Museum environment.
We go pretty ballistic on how we design our packaging. You can see this one is child proof. We build special boxes out of blue card, which is acid free. This forms basically a buffer between our already excellent environment in most of our repositories, given we have good temperature control and good humidity control. Then we pack this object away in its lovely beautiful box. This is an object that we acquired for the Miss Australia exhibition we had a few years ago which travelled around Australia.
Just briefly, speaking of trophies, you can’t actually clean this trophy without pulling it all apart, so this trophy was completely disassembled and all the parts were cleaned separately. The wood was waxed, all the silver surfaces were cleaned. There was a lot of Brasso and a lot of polish residues in these very fine detail works. It was just like a white paste. We document all the processes we do. In some of the earlier photographs of this in the disassembly stages, we actually photograph all the junk that’s lying around. The same thing happened in that every time it came out for a display or a pageant or whatever, someone would polish it up – ‘Quick, where’s the Silvo? Polish up the globe.’
When we acquired it, we got it ready for exhibition. It was a curatorial intent to have it looking sparkly and new and well cared for – not reconditioned but clean as if we got it in our cupboard at home in nice condition and we respect it and we’d like to keep it looking nice. So it’s not highly polished, it’s cleaned. The oxides are removed from it.
Therefore, what do we do to keep it in that condition for as long as possible? We build a nice box for it with good supports. You see these little pillars here. If we want to transport this to an exhibition say at the National Library for a couple of days, it can go in this box in a tub and go off travelling. There is also a goldie looking paper that you can see around here. We call this intercept. It’s not going to stop corrosion; it’s just something that is there to attract any pollutants that may be inside the box or in any other atmosphere that it might be exposed to. The pollutants will go to this paper before it goes to that. So this is the sacrificial paper. We can then after a period of time say, ‘Right, get rid of that. Pull that out.’ We will put a fresh piece in it, and it will do its job again.
This trophy was cleaned four or five years ago - I actually personally did this one - and it hasn’t changed one bit. We open it up and have a look at it once every 12 months - yes, she’s all good, nothing happening there, the paper is still working. These foam blocks are all archivally sound. They are not going to off gas and cause any problems inside.
So that is how we store them. You can see that we really put a big effort into looking after them and preserving them. By storing them properly and keeping them in a good, clean environment, we actually extend their life because we don’t have to handle them as much; we don’t have to clean and scrub and do the horrible stuff that happens with silver in a club.
One of the things about this process is that you don’t want to contaminate your solution, your cleaning, with a ferrous metal. Usually what you find with these trophies, the ones you’ve got in your cupboard at home, is that they’re usually made up of numerous components. This is a plastic or a back light. There is a piece of aluminium on there for the tag that has just been tagged on. If you want to clean that, just soapy water - don’t do anything else with that but that separates that from there. But you still have a steel component which will react with your cleaning process. Most of the time you can remove that and find the rest of it is all plated. Every trophy is different. A lot of trophies are manufactured and have numerous components. You go and say, ‘I want that, that, and that,’ and they bung it together. That’s why they can look as hideous as this thing and as elaborate as that.
Just keep this in mind when you are using this cleaning process - try not to introduce too many foreign metals all at once. Brass and silver goes all right. One other reminder about perforations in hollow castings or hollow components - block them off. That’s about it for storage. If you want to buy this stuff, you as a customer can buy it. You just go to the web and look up intercept paper or archival packaging. Most suppliers will give you product information and uses for those products.
NATALIE ISON: We are going to start a question and answer session. Does anyone have a question?
QUESTION: You say you want to look after copper, but I want to polish copper and brass. What do I do? I have a veteran car and I want a radiator that is shiny, brass and nice. What do I do?
ANDREW PEARCE: The best thing that you can do is do your polishing, using things like Brasso. But then, once you’ve done it, make sure that you are getting all of the residue off so that you don’t have any of the little green bits of leftover Brasso grime in crevasses.
PETER BUCKE: You brush and get it all out.
ANDREW PEARCE: The follow-up cleaning is going to be the most important thing. You have an advantage with copper and brass in that they are not a plating; they are solid the whole way through. A lot of the silver things are silver over brass or copper, they are not solid, so you can go through the plate. When you are dealing with something like a brass radiator, it’s not as much of a hassle because you’ve got 2mm or 3mm worth of brass there, so that wouldn’t be a problem. But the most important thing is to get that residue off.
We do sometimes put a lacquer coating over the top of copper and brass when we are treating them in the laboratory. But for something like a radiator where it’s getting hot and it’s out in an environment where you want to get as much air flow over the metal as you can, that’s not really a viable option.
PETER BUCKE: The marine chronometers that are currently being serviced in our open conservation exhibition, all the brass work in that actually has a shellac on it. A shellac is just bees’ wings with alcohol.
ANDREW PEARCE: Dissolved beetle bodies, I think.
PETER BUCKE: And you can actually get different colours. If you are using that on a motor vehicle part that has a lot of heat, you are just going to peel it off. If you put it on your radiator cowling, the heat is just going to burn it off back off again, so you are better it off leaving it raw. But the most important thing is if you are going to use abrasive polishes, wash the residues off - give it a really good rinse afterwards.
QUESTION: I wrap my silver-plated tea sets in Gladwrap and that seems to keep -
PETER BUCKE: The same.
QUESTION: So that works okay.
PETER BUCKE: Yes, that’s good.
ANDREW PEARCE: I think it would be worth putting something like a layer of acid-free tissue underneath the Gladwrap so that you are not running the risk of any of the plasticisers. Gladwrap, as a plastic film, has a lot of plasticiser in it to make it as soft and stretchy as it is. And those plasticiser compounds, the molecules, can react quite badly with the metal. So if you can get a barrier, something that will absorb it before it gets to the silver, that’s better. Preference would be to use a ziplock bag, rather than Gladwrap.
PETER BUCKE: A cloth or your acid-free tissue.
ANDREW PEARCE: But to keep the air and the pollutants out - great solution.
PETER BUCKE: You can purchase acid-free tissue in most stationers or in craft shops and things like that.
QUESTION: Thank you. I have a second question: Silver jewellery, I used Alfoil with washing powder. Is that okay?
PETER BUCKE: Aluminium foil?
PETER BUCKE: With silver jewellery, if it’s stone set you just need to be aware that with the really porous stones like lapis lazuli and some turquoises, you don’t put that in this solution because the porosity in the stones will allow the solution to get in there and then you are getting a bad reaction. You get expansion and discolouration of dyes, if there are any introduced dyes. You have to be careful of that. But if it’s a faceted stone - never put an opal ring, a triplet or a doublet in something like this, for example, because you will split the laminations apart and you will end up with a pretty ugly looking stone.
QUESTION: With stuff that is brass, can you put brass in that the same as the silver stuff or not?
PETER BUCKE: The brass won’t clean the same way - the result is not the same. For example with this lid which is brass and silver plated, if there is brass exposed it will not be affected by this process - but it won’t clean it.
QUESTION: If I had a brass vase or something. I used to buy those plates you get with the washing soda and then I moved on to the cheaper aluminium foil -
ANDREW PEARCE: Same thing.
QUESTION: I have never put brass in, but you are saying that I could do brass the same way?
ANDREW PEARCE: Not really.
PETER BUCKE: I don’t think you’d get a result.
QUESTION: It won’t be as good.
PETER BUCKE: You still have to use some sort of cleaner.
ANDREW PEARCE: It’s far more a sulphur specific process -
PETER BUCKE: - in the reaction with the silver.
QUESTION: With cleaning say an old silver teapot, sometimes there are different sections of handle and they are separated from each other by what may be ivory.
PETER BUCKE: Yes, plastic ivory. When you are dumping your object in the solution, say, for example, this teapot, you’d have one piece with one leg standing on it. That will cover everything that is in contact with that leg. This is not in contact with the aluminium. You could put it on the side like that so that the handle is in contact with that and the leg is in contact with that coupon.
QUESTION: Would the ivory be at risk?
PETER BUCKE: No. I have had really good success with the ivory. I mean, ivory is bone and it doesn’t seem to react at all - it’s fairly dense, strong.
QUESTION: Just a couple of small questions. You were talking about badges before, does that apply also to coins?
ANDREW PEARCE: With regard to what?
QUESTION: Cleaning silver and copper and other coins -
ANDREW PEARCE: Every time you are going through an abrasive cleaning process you are removing surface, so you will be gradually losing detail. Certainly with some old coins it’s preferred that they have a patina rather than looking like they have just been freshly polished.
PETER BUCKE: Preserve their originality and their life patina as well.
QUESTION: So it’s better in some cases not to clean them?
ANDREW PEARCE: Yes.
QUESTION: You mentioned the bakelite base on that trophy before. When it loses its shine, how do you get it back?
PETER BUCKE: Bakelite - I don’t want to comment. Conservation science is evolving, and there is always research being done. With bakelite, at this stage your safest method of cleaning is just an aqueous solution, maybe a bit of soap, and lots of rinsing. I have read a few articles about the treatment of bakelite and trying to rejuvenate that, but most research that’s been done by conservators clearly indicates don’t coat, don’t polish, soap and water, because I guess they are still trying to learn more about how it reacts. There is a lot of experimentation that goes on.
That’s why there is a conservator at the War Memorial who is a specialist in medals. If we came across a medal in our collection we would seek advice about it. We don’t go through any process of treatment until we know exactly what we are doing. Bakelite is still one that a lot of research is being done on.
ANDREW PEARCE: The knife switch there is mine, and I will admit that in cleaning that up when I first got it, I did actually polish the phenolite and bakelite components on that using Brasso.
PETER BUCKE: Which is a mild abrasive.
ANDREW PEARCE: Because it is a mild abrasive and I was using it as a polish. But it’s not something that I would do professionally for things within the Museum collection. For something of my own where I was going ‘Let’s using this as a learning exercise and see if it works and what effect it causes,’ I was willing to take the chance. But in that instance with that particular form of phenolite it’s been okay, but I’d be hesitant to go: ‘Oh yes, you can turn around and do it all the time.’
PETER BUCKE: Sometimes you don’t know what the future holds in respect of what you have cleaned that with. The detergents and the carriers of the Brasso, what reaction that will have over a long time of life with the plastic – whoops, I have destroyed it and it’s not going to be around for people to enjoy in 200 years time.
ANDREW PEARCE: And the plastic components are often made to a different recipe every time as well. There is no one standard. They misbehave in all kinds of interesting ways.
QUESTION: Bakelite, as I understand it, was a petrochemical process?
PETER BUCKE: Very plastic, yes.
QUESTION: I have a few old radios and telephones that have faded over the years and I just wanted to brighten them up. But you are saying - just clean them?
PETER BUCKE: Yes. As Andrew says, if you’re prepared to hit it with an abrasive polish, that’s fine, but you don’t know what’s going to happen down the end of the track. That’s why we always stay on the side of caution about processes. We have to be 100 per cent sure before we do something. If we are not sure, we won’t, basically.
NATALIE ISON: That’s one of the biggest things about our field as well. It’s a constantly evolving thing, because every material that we are working on is constantly being redeveloped. And also the treatments that we were doing maybe 20 years ago, the equipment that we use nowadays is a lot more reliable and stable. Again, it’s a continuous study to work out what the best process is and often, as we are pointing out here, the best process for one thing isn’t necessarily the best process for something else.
PETER BUCKE: So continual research and learning. We work in what we call an objects lab and we come across wood, plastic, glass, ceramics, metal, fine technological objects like our marine chronometers and scientific weighing scales - and every object presents new problems. The same as in paper textiles, there is never a process that repeats itself. You gain knowledge; you build knowledge; and then you adapt that knowledge; but you still have to research and study up a bit before you attack something so that you cover yourself. Because sometimes with things that were done in the past - not knocking what happened in the past - it can be too late.
Then there’s another challenge, how do I undo this process that someone else has created? Like your radio collection, take it home, put it on a muslin buff with jewellers’ tripoli and jewellers’ rouge, and you will get a wonderful finish out of it. But then in 20 years time you say, ‘I am going to donate this to the Museum.’ Then a conservator will sit there and say, ‘Why is this bakelite deteriorating?’ You will start looking into it, microscope, Raman microscopy, what’s happening here, and then finds there is some reaction because you have washed it with an ammonia solution or a household detergent that had such and such in it, and that’s started reacting with the iron in the jewellers’ rouge, which is just a fine powder in wax, and you are finding this problem starting. How do you reverse that? You are presented with a new challenge every time. That’s why guys like us go to uni for five years to learn the trade, and then you never stop learning. It’s a new game every day.
QUESTION: I have a very large brass wall plate and I have been using Brasso on it. So the best thing after the Brasso would be to make sure, because it’s fluted around the edges, that you wash that off?
PETER BUCKE: Yes, wash it off. Very simply: if it’s a very large plate, you probably find that you could go down to the shop and buy a nice little shoe polishing brush with a natural bristle in it which is reasonably soft. Have your vessel with water in it and a bit of household detergent, not too strong, and wash it and rinse it and wash it and rinse it. Do that until you can look across it and say, ‘No, I haven’t got any white residues,’ or with brass sometimes it just turns green for reasons that Andrew explained before.
QUESTION: Would I be better off putting some sort of shellac covering on it?
PETER BUCKE: Then if you need to do it again, because the metal will still oxidise under shellac if there is a pin hole or a gap in it - it will just creep underneath it. Like the clock cases that I have in there at the moment, there will be one little pinhole and the oxidisation will start and then it will creep underneath the shellac. Then you have to remove all the shellac.
ANDREW PEARCE: You can get archival-grade museum waxes. It’s a wax polish that puts a film all over the surface so that you are not getting the moisture and the pollutants through.
PETER BUCKE: If you need to remove that, you can actually wash it off and start again.
QUESTION: Where would you buy something like that?
PETER BUCKE: Go to the web and look up museum wax.
QUESTION: Because it doesn’t tarnish in Canberra nearly as much as it did in Sydney.
ANDREW PEARCE: In Canberra we don’t have any heavy industry and we have a much lower level of trucking going through.
PETER BUCKE: Our air is pretty clean.
ANDREW PEARCE: So we have quite clean air here. That makes a big difference.
NATALIE ISON: Our temperature fluctuations are nowhere near as severe. The humidity is nowhere near as high.
ANDREW PEARCE: And we’re not close to the beach.
NATALIE ISON: Canberra is a really good storage place.
PETER BUCKE: The drier the better. But try tubbing it and see if you can get yourself some microcrystalline wax and coat it with that. Then you will find if you do see oxidisation starting or darkening, you will probably then have to remove all that wax. You have to do that with alcohol, petroleum spirits or whatever the base is for the wax that you have bought to wash it off. That’s a big job and a lot of elbow grease in reversing something like that. You might be better not doing a wax coating if you are not sure.
NATALIE ISON: The other thing that I have to let you know about is to remind you that, if you are interested in asking any other questions, we are downstairs between 11am and 3pm every day in the temporary gallery. The Museum also has a feedback form. That would be about it.
ANDREW PEARCE: Thank you very much for your time.
PETER BUCKE: Thank you.
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Date published: 01 January 2018