How to etch a brass shell casing without acid

Recent commission

I am sorry that I have been remiss in updating the blog over the last few weeks, but I have been suffering with a winter virus that has knocked me off my feet. I am back now, so hope to provide a few pieces that may interest readers over the next day or two.

My first piece follows on from an earlier entry that I wrote entitled 'Works in Progress.' In that article I described the use of 'sugar lift' as a means of transferring an image. This can be viewed by checking out this link: http://trenchartswordsintoploughshares.blogspot.co.uk/2012/07/works-in-progress.html, or by clicking on the link in the index from July 2012.

The Burma Star Medal

The Commission:

I had been commissioned to create a shell casing for a veteran of the Burma Campaign, holder of the Burma Star, and member of the Burma Star Association (http://www.burmastar.org.uk/) This was intended as a gift to commemorate Armistice Day this year, and was to be delivered yesterday when my friend who commissioned me, the gentleman in question, and myself were due to go out to dinner together. (I was working to the very last minute, but the casing was delivered on time! More of that later).

My initial ideas of working with the image of the Burma Star were not really working for me. I needed to do more that just etch an image as Major Michael's eyes are not as good as they once were, so had to find a way to make an image that was relevant, and at the same time more visible. In order to ascertain what might be appropriate, I arranged to take him out for a trip to the National Army Museum in Chelsea, London, for the day (http://www.nam.ac.uk/), followed by a pint or two in one of his local pubs. He was unaware of the Commission, so it gave me the opportunity to get to know him, and to gently pump him for information on what his interests are and to hear his history, not just as a soldier, but the family man and professional outside of his army experiences.

We both had a great day, but he ended up drinking me under the table at 89 years of age!! lol

In our conversations over the day, I found out that his regiment was The Royal Engineers, and that the Regiment was as important to him as the Burma Star Association. With a little research I found the image that I eventually decided to use, and one that allowed me to revisit an experiment that I did a few years ago when I first started working on shell casings, utilising glass paints to introduce colour to an image. The choice of image raised another problem, the need for precision in the execution of the design, so 'sugar lift' and its inadequacies in creating fine detail was not really going to work on this project.

Final design and notations from my sketch pad

My solution to the problem of precision was the utilisation of water colour paint, but more of that later.

Choice of shell casing:

The unpolished shell casing and base with annotations

Having now chosen my design, I had to choose an appropriate shell casing. I normally use shell casings appropriate to the project that I am involved with as it is a major element of the final product and adds a layer of meaning to the whole endeavour. My choice was a British 18pr dated 1913 (see the above illustrations).   

A 'fluted' shell casing

As the commission was for 'Armistice Day', I decided to make the link with the First World War rather than the Second. The Burma Star is obviously to do with the latter, whereas the Royal Engineers were involved in the former. (As an aside into the history of Trench Art, the Royal Engineers and their equivalents in other National Armies were at the forefront of some of the more ambitious and striking designs for the creation of shell casings as they had the tools, machinery, expertise and raw materials at hand to enable, for example, fluting - see above photograph). 

The date on the chosen shell casing can be seen to be 1913, and is the closest that I have to 1912 (to make it as relevant to this year as possible, and to make it an official antique come January 1st next year, so there is the juxtaposition of the modern with the antique). Although it is officially pre-war, I have noted that it has been reloaded and fired at least 3 times, and as it was sourced in France, I believe that it was utilised during that conflict. It was common to use all the munitions that were to hand in this and other conflicts and, even though they were left on many battlefields, still remained the property of the respective armies that bought and fired them, hence very few pieces of Trench Art being signed! 

N.B. Although I sourced this and other shell casings (both plain and decorated) from a trip to France, where they can be picked up quite cheaply at markets and second hand shops, they are still available at flea markets, car-boot sales, and auctions in the UK and in other countries. Another source is Ebay, although they can be relatively more expensive on that site.

Preparing the shell casing.

Once the shell casing has been chosen, the surface needs to be prepared to enable it to be ready for an image to be transferred and for it to be etched.

Firstly the years of grime and oxidisation need to be removed. On shell casings that are in good condition, this may only require an overall polish with a domestic household product such as Brasso, however, on more oxidised and patinated casings, something more caustic may be needed, such as Horolene (available from most good DIY stores or from the internet) before polishing with Brasso.

Once the surface is cleaned, it will need to be degreased to enable the resist to adhere well. Here is an exert from 'Printmaking Handbook, Colour Etching, by Nigel Oxley' (my old tutor at University) ISBN 9780713668209. Substitute the word 'plate' for 'shell casing':

All plates need to be degreased before a ground is applied. Degreasing entails rubbing the surface of a plate, using a clean cloth, with a paste made up of ammonia and French chalk... When the whole surface has been covered it is put under a tap (of running water). If degreasing has been successfully completed, the paste will wash away leaving a continuous film of water in its place. Should there be any patches remaining, the process is repeated. (Ammonia is foul smelling, and for this reason I have replaced it with a household cream cleaner which requires no mixing and is readily available). The wet plate can be dried speedily with a hair-dryer. When there is just a small amount of fluid still visible, a clean dry cloth should be used to remove the inevitable residue of powder. Once the plate has been degreased it is ready to receive an acid resistant ground.

N.B. In my experience, it has been difficult to fully degrease shell casings. I am not sure if this is to do with the age and deteriorated surface, and this is what makes the use of sugar lift a little hit and miss. However, so long as it is degreased enough to hold the 'resist,' the technique that I will describe will give the ability to create delicate and fine lines.

The Resist:

Although there are other alternatives, the resist that I choose to use is 'Straw Hat Varnish,' available from good art stores and from printmakers suppliers. This is available in either a metal bottle or in a glass bottle. I have found that after use, the metal bottles can be difficult to open and the top become stuck from the residue of the varnish. In trying to open the metal cap, it can become distorted and allow air into the bottle which thickens and sets the varnish, rendering it unusable  so I would therefore suggest you buy the glass receptacle for convenience and to keep the varnish as fresh as possible.

The shell casing with the the resist in place. I have not varnished the base, and have concentrated on the areas to be etched. This is 'touched up' before etching.

The resist creates a barrier between the surface of the item to be etched and the etching solution. Where the metal is exposed, it will create an etched surface, so care needs to be taken in the application of the resist, to ensure that all areas (including the interior of the shell casing) are fully covered. I would suggest 2 thin coats of varnish to create a good resist.

As a pallet for to hold the varnish, I use the plastic lid of a takeaway carton that can be thrown away afterwards, however if you use something that you need to keep, a wipe over with a tissue or cloth with a little Methylated Spirit, which will, if the surface is not porous, clean the varnish off. To apply the varnish, I use a cheap old flat headed water colour brush, which again, because the varnish is Methylated Spirit based, is cleaned in Meths and washed with a drop of soap and water. I use the water colour brush as it is soft and gives a good consistent coverage on the surface of the casing. (Remember to put newspaper on the surface that you are using to save having to clean it with the Meths, as any spills and drips will be absorbed and then the newspaper thrown away).

The varnish is quite quick drying, however, I occasionally give it a hand with a hair dryer. Temperature can affect the varnish. The warmer the weather, the quicker drying, both on the surface of the shell and on your pallet, so you may need to work quicker in the summer than in the winter.

Once dry, you are now ready to transfer your image. (If you are using sugar lift, you would apply this before the varnish, ensuring that the sugar lift is fully dry before applying the varnish).

Transferring the image:

Water colour applied to take the transferred image.

As I stated at the beginning of this posting, I have found that, to get a precise image for very fine detailed work, sugar lift was not going to be appropriate for this project. I usually transfer the image with carbon paper (available from good stationers and, as I have found, the £1 shop)! As the varnish is almost black, it cannot be used directly onto the surface and still be easily seen. My solution was to create an area on the surface of the shell casing that would be big enough, and at the correct level for the etching, in water colour paint applied with the brush used for the varnish, and a little water, as can be seen above. The water colour will be washed off, so it does not have to look perfect, it just needs to be able to take the image and allow it to be seen.

Having traced my chosen image onto tracing paper, I attach it to the shell casing with masking tape. (The bottom of the tracing paper lined up on the base of the shell will enable you to line the image up correctly and keep the image straight, alternatively, a steel ruler resting on the lip on the base of the shell casing can be used to draw a 'centre line' in felt tip pen onto the water colour surface and lined up with a centre line drawn on to your design achieves the same ends).

With the tracing paper attached to the bottom and right hand side, the water colour surface can still be seen underneath. (Please excuse my lack of photographic expertise)!

I attached my tracing paper on the bottom edge and on one side only. This enables me to see the image against the surface of the shell. Once I am happy with the positioning, I then slide the carbon paper between the tracing paper and the surface, ensuring that the whole image is covered by the carbon paper before finally securing all pieces to the shell casing. As the masking tape comes away easily without damaging the varnished surface, it is worthwhile taking as much care as possible to get this step correctly lined up and taught to the surface of the casing, so that the tracing paper and carbon paper do not move during the transfer.

All papers are secured in position with masking tape

Once you are happy that the image is correctly positioned, a hard pencil or ballpoint pen is drawn firmly over the image to be transferred, until the whole image has been covered. If using a ballpoint pen on an image drawn in pencil, this is easily seen, however if you are using pencil on pencil, by positioning the whole piece at an angle to a strong light source, you should be able to see where extra pressure has indented the tracing paper over the original drawing.

Checking that the full image is transferred before removing the tracing and carbon paper fully.

When you are confident that your image has be fully transferred, keeping one edge of your design attached to the shell casing, open the layers of paper to check that the design on the shell casing is complete, if not, because you still have your papers attached, it is easy to reattach and trace the portion that is missing without fear of having to line everything up again precisely.

As can be seen in the photograph, the image is clearly visible and ready to work on. At this stage, it is possible to add anything that you wish to the design with a soft pencil, even making notes for yourself as at this stage, none of the work that has been done is likely to leave any markings on the actual surface of the shell casing.

Scribing the image for etching:

Beginning to reveal the image to be etched

The intention at this stage is not to scratch the surface of the shell casing, rather to remove the layer of varnish from it. It is not about gouging out the image from the metal, more, to reveal the surface below to enable the etching fluid to work on the areas exposed.

Nearly done. Note that the leaves are only outlined at this stage, and that the velvet cap in the crown is only outlined. Further detailing will be done during the etching process

I am fortunate enough to have a couple of different etching needles especially designed for this process, however, any sharp point will do a similar job. I would suggest taping a darning needle to a pen or pencil, or to stick it into a cork and experiment. Dependent on the desired finesse of the design, anything that removes the layer of varnish is suitable. For example, a fine water colour brush dipped in Meths would work, or for a more painterly effect, using different sized brushes with a freehand design would give some interesting effects.

For those with printing experience, it is worth pointing out that my designs are not done in reverse as the object itself is the end product, rather that an intended print, so if the image is to be seen in a specific direction (for example if there is lettering) that is worth keeping in mind. However, the intention may actually be to utilise the finished shell casing as a printing plate, and if you do, I would be really interested if you could send me an image of the results!

Touching up the varnished surface before etching, removing minor scratches. I find a head magnifying glasses indispensable for detailed work

As will become evident at a later stage, once my outlines are established, I can choose at which point I remove surfaces to be etched, or add varnish to parts of the design which are etched enough while still continuing to etch other areas.

At this stage I gently wash off the water colour paint under a running tap as I am not sure if there would be any reaction with the etching solution. This should be a very easy process and be done in a matter of a couple of minutes.

The etching solution:

When I first began etching shell casings at University, I encountered the difficulty that the ferrus and nitric acid solutions that we used for etching plates hardly made a mark on the shell casings. Etching plates are usually zinc, copper or steel, whereas the shell casings are brass.

Having discussed the problem with my tutors and the print room technician, I was sent off to do my own research. Having spent hours on the internet, the technique that seemed to answer my problem was called the 'Bordeaux Technique,' after the region of France where the ingredients are used on grapevines! To cut a long (and boring) story short, here is the recipe that I came up with:

1 part Copper Sulphate (available from printers suppliers or good gardening centres)

1 part Table Salt (available from your local supermarket or grocery store)

5-7 parts Water (dependent on the strength of solution required - available from your kitchen sink)!

You will also require a 'bath' to contain your solution, a bottle to decant the solution into once you have etched your shell casing, for future use, and household Soda Crystals to neutralise the copper sulphate during etching and for disposal of the copper sulphate once you have finished with it.

The shell casing fits nicely into the bath with room to manoeuvre 

The copper sulphate I sourced from Hawthorn Printmakers Supplies at www.hawthornprintmaker.co.uk. For the etching 'bath' I have come up with two cheap and easily obtainable solutions. My first one for a very large shell casing was a plastic window box which was big enough to contain the shell casing (but make sure that there are no holes in the base)! The second, as can be seen, for smaller shell casings is a small plastic packaging case that I found on the street. (I filled it with water before the etching solution to check that there were no splits or holes). For the decanting of the used liquid for storage, I use large 5Ltr water bottles.

I also use an old tooth brush to clean the surface of the etching metal, (you really would not want to be using it on your teeth after it being in the copper sulphate)! and a large goose feather to agitate the solution to prevent bubbles and detritus affecting the etch. I also advise the wearing of disposable rubber gloves while handling the liquid and a face mask that can be picked up cheaply from a DIY store.

Once you have a receptacle to hold your casing and your liquid, an easy way of checking how much etching solution that you will need is to place your casing in the bath, pour in as much water as you need to cover the casing, take out your casing and then measure the amount of water that you have with a measuring jug. Although a little laborious, you do not end up with too little solution to cover the casing.

The etching process:

Filling the bath with etching solution

Agitating the solution with a goose feather

With everything that I need in place, and a mobile phone set to timer, I am ready to commence my etching. Placing the the shell in the bath, I proceed to pour the etching solution in to the required depth, and start my timer. I initially set it for 5 mins. I use the aforementioned goose feather to remove any air bubbles from the surfaces and to prevent the build up of any sediments on the surface of the casing.

When removing the casing from the bath ensure that you break the surface of the solution with the open end of the casing to ensure control over the removal of the solution from the interior of the casing

Once the timer rings, I remove the shell casing from the bath and immerse it in my sink which I have already filled with water and added soda crystals to neutralise (stop) the etching solution. I have learned by experience that the easiest and safest way to remove the casing from the etching solution is to break the surface of the liquid with the open end of the shell casing so that you do not create a vacuum which can lead to a deluge of liquid covering yourself and the surrounding area! Not a nice mess to clean up and a real pain in the ass!!

Neutralising the etch in a soda crystal and water solution

Once I have neutralised the surface of the shell casing in the solution of water and soda crystals, I inspect the surface of the etch. As can be seen in the photograph, the exposed surface has turned a dull yellow colour, which shows that the etching solution is doing its work. This yellow 'crud' can be gently removed by replacing the casing into the soda solution and gently cleaning the exposed surfaces of the metal with the old toothbrush. This enables the etching solution access to the exposed metal and to carry on its job of etching. Please note that you are only gently removing the surface of the 'crud' you do not expect to see shiny metal underneath as this would run the risk of scrubbing so hard that you begin to remove the varnish resist, which is not advisable.

Inspecting and cleaning the etching shell casing

At this stage do not expect there to be a deep etch. I know that the solution that I am using has been used quite a lot, so is going to take longer to etch the metal, however, this process is much slower than using acids on other metals, and for those that are familiar with etching, tends not to undercut the metal lines to the degree that the acid baths would normally do. All I want to know at this stage is that the etching solution is doing its job, and that I cannot see anywhere that I need to touch up by either removing more varnish, or adding more varnish.

As can be seen in the above photograph, any bits of varnish that have been left on larger 'open bite' areas quickly become obvious and can be gently removed before the etch really starts to take hold. Care of the detail at this stage will serve you well later. At each inspection stage, I check the surface being etched under magnification. I also make notes in my sketchpad each time I take a step. I make note of the time spent in the bath and what I did after neutralising the casing. This helps when you come to repeat the process on future projects.

Detailing added during the etching process can be seen to the crown and the leaves. As it is as yet not etched, there is a noticeable difference in colour

From here on, the process becomes very repetitive, as those familiar with the etching process will be familiar with, so I will briefly share with you my notes from my sketchpad, beginning with the next immersion into the bath.

20 min etch to establish etched lines and to see how quickly etching solution is working. Regular agitation with feather or by rocking the bath.

• cleaned with toothbrush
• minor flaws touched up with varnish
• image cleaned up with etching tools where necessary

20 min etch:

• Cleaned with toothbrush
• detailing added to 1/3 of leaves and crown

20 min etch:

• after cleaning checked for undercutting of linear work particularly on crown detailing and inscription
• further 1/3 of leaves detail added

20 min etch:

• cleaned with toothbrush
• etching nicely
• no further work

40 min etch:

• cleaned
• etch is sufficient for my needs

How do I know if the etch is deep enough?

Other than through the visual inspection under magnification, if you gently catch your finger nail against the side of an etched line, if your finger nail catches, there is a sufficient etch to make an image. It is worth remembering though, that my tutor Nigel Oxley's mantra was 'It is better to over etch than to under etch. Any image is better than no image at all!'

For those unfamiliar with the etching process, it is a matter of trial and error. If you can pick up pieces of brass ware cheaply at junk shops and the like, try out the processes on something cheap and disposable if you do not have the confidence to go all guns blazing (no pun intended) at a full project.

Cleaning the shell casing after etching:

I call this 'The Reveal' and am as excited by it now as I was when I first made an etching plate. It is almost like magic, as it is hard to fully conceive your creation until the varnish is removed! This is one of the most simple, quick and satisfying of all processes, and a sheer delight and triumph when it has all gone correctly. I am not overly bothered by minor flaws as the shell casings are ancient and temperamental. What I am interested in is the all over effect and impact that the etched image(s) have aesthetically on the shell casing. I hope for something that looks good and pleasing to the eye. It is about satisfying myself more than it is about pleasing others. I believe if I achieve the former, the latter follows closely behind (or does that sound like arrogance? It is not intended to).

Here is where Methylated Spirit and a clean cloth come into their own! Wiping over the surface of the varnish with these simple items which many have to hand already in their own homes, swiftly reveals the product of your labours.

Once all of the varnish is removed (I leave the varnish in the interior of the casings for aesthetics) you are ready for what would normally be the final polish with Brasso, although for this project I have a couple of further steps whereby I colour the image with glass paints and toast them in the oven. If anyone is interested in that aspect, just ask and I can cover it separately. 

For those that have not lost the will to live after such a long post, both Philippa who commissioned the piece, and her cousin Major Michael Murray were thrilled with the results:

'It is more beautiful than I ever expected!' Philippa

'Astonishing! I shall treasure it for the rest of my life.' Major Michael Murray.

N.B. For those of you who noticed, I am not an octopus and only have two hands. The photographs where both of my hands are in use were kindly taken by my partner Andy! lol 

I am happy to answer any questions that readers may have, to provide further photographs or any clarifications that need to be made. Now I'm off for a long delayed beer!! lol

UPDATE:

For disposal of the Copper Sulphate solution and for advice on which other metals that can be etched, please follow this link:

http://trenchartswordsintoploughshares.blogspot.co.uk/2012/11/how-to-etch-brass-shell-casing-without_21.html