THE THREE BASIC STEPS FOR AN INVENTION
1. INSPIRATION - which is usually derived from Necessity......
2. DESIGN – the ability to express your inspiration either by an artwork or engineering drawing.
3. PRODUCTION - the skills and techniques used to produce it.
This brass keychain was designed for a friend of mine, who is a wildlife tour guide, I happened to meet him at a party and decided to help out, as he wanted to gift some souvenirs, to a tour party that was arriving in a week's time. It had to be small so he could carry it with him, so I decided to do this mini brass key chain of a Leopard, which matches the colour of brass. I reside in Sri lanka ( I guess God positioned me here for a purpose) an Island country which is at the southern point of India, Sri lanka is famous for its Variety of the Asian Elephant, the Leopard & the Peacock…
The artwork needed to be done in Black & White and was done from a photograph of a leopard; it was first photocopied and scanned, uploaded into CorelDraw and enlarged in the window… I then drew over the black portions of the picture using the various tools in CorelDraw... starting with the outline, the eyes and the features… it took me around five hours to complete, taking printouts regularly to edit the fine details. I finally had an artwork which could be inverted (converted from positive to negative), or converted into a bitmap image.
I scaled it down to the required size and decided to mount the complete 2D brass engraving on a 3mm Black acrylic base and attach a gold key ring to it.
Unfortunately I do not own a CNC engraver… so I decided to use the chemical engraving process… which is named as etching…
To those of you who own CNC engravers I would say it is a quicker, easier and cleaner process of production… and could be done on a wide range of materials…
Since the subject here is invention the production process is open to your choice…
Given below is the process for etching sharp images on sheet brass, beautifully polished and finished…
1. A Knowledge of Screen Printing is required for this, for those who wish to learn here is a URL from YouTube,
2. An artwork printed on a sheet of transparency, This could be done on a black & white Laser printer; using A4 tracing paper 80 Gsm, the black contrast should be high, so that very little light passes through it. NOTE: an negative image of the artwork is exposed on the screen for etching on Brass. The Video on You Tube shows you the process of screen making; exposing and printing… thus I will give you the essentials for printing and etching on brass sheet.
3. Brass Sheet SWG 24
4. A screen emulsion for stencil making…I used AutoTYpe. AUTOSOL 2000 and sensitized it with two drops of a 20% solution of Ammonium Dichromate…
5. SS screen Ink, I used an ink which is could be cleaned with Kerosene oil, it assists in sharper printouts
6. Etching Solution.. Ferric Chloride crystals mixed in water 35% Solution, add 2% Citric acid into it.
7. A neutralizing solution of 100gms Citric acid & 100gms Table salt, mixed in 1.5 liters of water.
8. Black Acrylic spray Can
9. Clear Acrylic spray Can
10. 800 grit water sandpaper
11. Two Plastic trays, flat bottomed, one for etching and the other for neutralizing..
12. Brass Polishing Compound if using a cloth buff or Brasso. Metal polish if hand polished.
13.Black Acrylic plastic sheet 3mm thick cut in 1.5” strips.
14. Some gold colour metal key rings…
THE PRODUCTION PROCESS
1. Draw the artwork as instructed in step 1. Size it and convert it into a negative image( this is the image that will be exposed on the screen) take a print out of it on a A4 tracing paper 80 gsm will do. A shown in the artwork in step 1.
2. Prepare the screen as shown in the Youtube Video… I used a 140 mesh Cloth… (approximately 0.1 mm Hole Size)
3. Mix the screen emulsion, I used Autotype, Autosol 2000 Sensitized it with two drops of Ammonium Dichromate ( A 20% solution of ammonium dichromate and water). This gives an exposing time of 45- 60 seconds in bright sunshine. remember as the emulsion gets dry it is sensitive to light.
4. Apply it on the screen as in the video, and dry with a hairdryer. Expose with the printed artwork.in sunshine timing in accordance with the emulsion used as seen in the video.
5. Develop the screen by spraying water; I used a plastic Coca-Cola bottle with a hand sprayer screwed onto it at the top. The same type of sprayer used for home window cleaning solutions. The screen that I developed is shown in Step 3. Note: There are other stencils in it too...
6. After developed dry the screen well.
7. Cut the brass plate into 1.25” strips and then cut into smaller pieces of 2.5” file the edges so it won’t damage the screen cloth while printing.
8. Fix the screen on two hinges, and then attach on a flat board, the contact distance between the plate and the screen is 1mm for brass plate,
9. Print the image one plate at a time, using a sharp rubber squeegee, Check for clarity and place on a baking tray, I used an SS ink which could be cleaned with kerosene oil, this is a slow drying ink and it gives very fine print details.
10. Dry the printed plated in a baking oven at low temperature for 20 minutes, wait for two hours to cool and remove the plates for touching up if required; a fine point could be used to scrape smudges…
11. Heat again in the baking oven for another 20 minutes, after it is cooled, place it on a paper, face downwards and spray some clear lacquer on the back of the plates so that the behind will not get etched when it is placed in the etching tray. dry it well.
12. Attach a strip of cello tape on the back of the plates, holding 5 to 10 plates together, depending on the size of the plastic etching tray, this is to prevent the individual plates from moving during the etching process…
13. Place the plates in the plastic etching tray print side upwards… and pour the ferric chloride etching solution. After it has been prepared and cooled in the way shown in requirements. Pour enough etching solution to cover all the plates, at least ¼ inch, place the back of the tray on a 1” strip of wood and move up and down in a vertical direction so that the solution moves over the plates freely, use a soft 1” paint brush to brush and clean the top of the plates as they get etched, do this occasionally, too much brushing may spoil the printed surface. Etch for 20 to 25 minutes according to desired depth of etch. I used a tray that could etch 50 plates at a time.
14. Next place the plates the etched plates in a neutralizing tray containing the neutralizing solution. Brush till the etched area is clear from the oxide stains of the etching solution.
15. Clean and dry the plates with a soft cloth do not use water. To wash them as they will get oxidized. Then finish the edges of each plate by cutting with a shear and filing.
16. Spray the Black spray paint over the etched surface in three thin layers leaving enough drying time within each layer.
17. When the paint is fully dry sand the plates with water sandpaper, using a wooden block, the image of the print will now appear in brass, polish with brasso or use a soft rotary buff and buffing compound, clean it well and give it a coat of or two of clear lacquer the initial layer must be very thin. Give at least 20 minutes drying in-between coats.
18. Shape the black acrylic plastic board as shown in the key tag, and finish according to the picture given, by pasting on the acrylic backing or the way you require it.
20. The Picture shows some other key tag souvenir and gifts that were done later...