Corvine Art Notes...

This page will be added to and is meant to become a repository of notes and explanations to do with all parts of the printmaking process. Many of the public visiting David's exhibitions have not come into contact with etchings and to a degree, lino prints either. Often mistaken for an off-set or digital print, the whereabouts of the original is often enquired after. This is a reasonable question too, and an article theorising the physical location of the original in a limited edition of a hand processed block and a hand printed product will be added to this page soon.

What is an etching then?

Above is an image of print and block. In this case the block is a zinc plate. In order to arrive at a print the zinc plate is first etched. And this process while simple in concept still requires a few steps to be followed, as described in Detailed Notes on Etching Process below. In essence a coating of something both acidproof and waterproof, usually a bitumen or tar of sorts is used to coat a zinc plate. When a needle is used to draw an image upon the prepared plate, the action reveals the zinc plate. When the plate is then immersed in a weak nitric acid solution, those areas opened up by the needle are etched, small cavities and canyons are created by the chemical reaction.

After lines have been etched, the plate is cleaned and then sprayed with a bituminous substance to create an irregular pattern of minute dots. By the application of more bitumenous fluid with a brush, at first white areas are painted on the block. After each application of bitumenous liquid, the plate is momentarily immersed in the nitric solution mentioned earlier. By this incrimental method of painting and etching, graded texture can be made across the plate. The varying texture over the plate will hold a varying amount of ink for printing.

Latest fun tool...
Digital micropscope on flex rod and light stand!

Below is a detail of a copper plate that was aquatinted and then scanned at 1000dpi. Admittedly, the copper plate was rather old and the documentation will be carried out again with a polished plate, soon...

Below that are a series of images derrived from the digital microscope. Each image relates to either a central sample of the aquatint, or a sample of the transition between one tone and the next. This texture is how ink is retained on the block.

Below that again, are two strips of images taken from the print taken from the block. Not precise enough this time... but soon.
  1. Managing Director
  2. Managing Director
  3. Managing Director
  4. Managing Director
  5. Managing Director
  6. Managing Director
  7. Managing Director
  8. Managing Director
  9. Managing Director
  10. Managing Director
  11. Managing Director

Click for more detail of copper plate

Click for more detail of print

  1. Managing Director
  2. Managing Director
  3. Managing Director
  4. Managing Director
  5. Managing Director
  6. Managing Director
  7. Managing Director
  8. Managing Director
  9. Managing Director
  10. Managing Director
  11. Managing Director

Old experiments

Before the microscope arrived, a fairly average camera was used in conjunction with a stand mounted magnifying glass and zoom lens. Although no match with the microscope, the combination of lenses gave reasonable results.

Click below for a sample of the images obtained

  1. Managing Director
  2. Managing Director
  3. Managing Director
  4. Managing Director
  5. Managing Director
  6. Managing Director
  7. Managing Director
  8. Managing Director
  9. Managing Director
  10. Managing Director

Detailed Notes on Etching Process

1. Choose a zinc sheet or copper sheet

Zinc...
+          faster etch
+          when drawing on prepared plate, lines are of higher contrast with hard ground,
            easier to see
+          usually painted on reverse and protected on front with clear contact, so unscratched
-           more prone to under-biting
-           more expensive

Copper...
+          finer lines are achieved with less chance of under-biting
+          cheaper
-           longer etching time

2. The metal plate chosen is inspected, least damaged side is usually preferred
  1. Wet and dry sand-paper can be used to deal with most scratches, bought at a hardware store
  2. Wet and dry sand-paper is used, the metal plate is sanded wet, flushing the plate from time to time with water
  3. If the scratches are deep 180 grit paper is used first
  4. Next, something like 400 grit paper is applied
  5. Then 800 grit
  6. And finally 1200 grit or higher
  7. The plate can also be polished using Silvo for zinc and Brasso for copper?
  8. A mechanical buffer could also be used, visit Jewelry probably
  9. NB polishing surface inhibits a good turps release…
  10. Once the surface has been sanded and polished, plastic contact can be affixed so as to protect the surface
  11. The back of the plate is then covered in contact too
  12. Very deep scratches can either be ground out with a hand grinder or burnished, which will be discussed later
  13. In other words, it's best to possibly begin with an unscathed metal plate

3. Now the reverse of the plate must be protected from the acid solution to be used later
  1. Plastic contact can be adhered to the back
  2. A suitable enamel spray like Pot-belly black can be sprayed on back
  3. Hard ground can be brushed on or sprayed on the back but will get scuffed and need to be retouched continuously

4. The metal plate's edges are filed to roughly to a 45-degree bevel
  1. Then scraped with metal ruler or scraper tool
  2. Can even be sanded and polished
  3. Corners can be rounded too
  4. The plastic contact protects the chosen surface through this process
  5. The bevel and rounded corners reduces chance of paper crimping during printing later or simply cutting paper and blankets

5. Now the plastic contact is removed from the side to be etched
  1. Plate surface must now be cleaned
  2. Turpentine can be used to remove grease
  3. Methylated spirits removes residual plastic contact glue and residual Turpentine
  4. Finally, chalk and acetic acid are combined on the plate to make a stiff paste, which is worked over the plate, thoroughly rinsed off with water and then dried
  5. Plate is now grease free, smooth, beveled and ready for grounding

At this point a number of processes can be entered into, which will be discussed later...
For now, we will proceed as for a line etch...

6. Application of hard-ground
  1. Plate is placed on a slip sheet of waste paper which helps transporting the heated metal plate and provides some protection for roller as hard-ground is applied
  2. Plate is heated on hotplate till the knob of hard-ground is able to be smeared on and is runny and glossy
  3. A rubber roller is run back and forth over plate to evenly distribute the hard-ground
  4. As per inking up with a roller, allow roller to spin a little between rolls, for eveness of ground applied and to rest the roller from constant heat which will damage the rubber roller
  5. Care must be taken not to overheat the ground
  6. Care must be taken not to melt or overheat the rubber roller
  7. Don’t leave roller rubber side down ever and certainly not on the hotplate for it will melt
  8. Hard-ground rollers are used only for hard-ground, soft ground for soft etc.
  9. If you are having difficulties with even coverage or dust and grot, check the roller and see if it is worth giving it a clean with turps
  10. The resulting covering of hard-ground need only be the colour of honey
  11. Allow the hard-ground to cool
  12. A thick black covering of hard-ground presents problems in drawing and etching
  13. Hard-ground is essentially an acid resist or stop-out or block-out

7, Making a line
  1. A line is achieved by drawing an etching needle across the prepared surface
  2. Wherever the metal of the plate is revealed by the needle, wherever the hard-ground has been scratched away, the acid solution can access the metal plate, etch it
  3. The revealed metal will be eaten away, these areas will hold ink in the intaglio printing process
  4. Crosshatching, stippling and many more drawing techniques can be employed without ever worrying about aquatinting
  5. Many drawing tools exist and many implements can be used as drawing tools, like a wire brush, scalpel, roulettes, anything really

8. Etching a line
  1. Suitable protection is worn, acid proof gloves, vapor mask and goggles
  2. The plate is immersed in a suitable solution
  3. Nitric acid diluted in water for zinc
  4. 1 part nitric to 6 parts water = line etching solution
  5. 1 part nitric to 11 parts water = line etching & aquatint solution
  6. 1 part nitric to 16 parts water = aquatint & fine line etching solution
  7. Dutch mordant for copper which is a solution of Hydrochloric acid, potassium chlorate and water
  8. Tiny bubbles will begin to appear wherever the metal is exposed to the acid solution
  9. These are swept away with a feather from time to time while the plate is submerged, which helps to discourage under-biting or fouling
  10. One need not constantly feather the plate though attention to the etching process is needed at all times
  11. The depth of line is related to the length of time plate is immersed in the solution
  12. The depth of line is checked by removing the plate from the solution
  13. The plate and your gloves are rinsed thoroughly and then plate is dried
  14. With eye, magnifier, needle or even fingernail (digital feeler guage) the depth of line can be inspected
  15. If a needle can be lodged in a line without fear of it skidding out then ink is going to be retained in the line, ditto with fingernail
  16. Any amount of time in the solution is going to etch the plate, light lines can be saved by painting liquid hard ground over them as required
  17. Zinc will etch quickly
  18. Up to 15 seconds will probably result in a light line which retains little ink
  19. The deeper the etch, the longer in solution, the darker the line which retains more ink
  20. A deep line should be well and truly established after 3-4 minutes
  21. Copper in Dutch mordant reacts slower than zinc, yet is checked regularly for depth of line
  22. Line etching is possibly checked for depth many times until the artist is happy
  23. If at any time hard-ground begins lifting off the plate arrest the process by removing plate, rinsing thoroughly and probably re-applying hard-ground and all that entails

9. When an acceptable depth of line has been achieved...
  1. Hard-ground is removed with turpentine and a rag
  2. Oil from turpentine is removed through applying slurry of chalk and acetic acid again
  3. Plate is thoroughly rinsed and dried
  4. Plate should be ready to ink up and proof

The line etch may be worked on further, blocked out and added to. Line has seemingly endless potential and can comprise the image. Many ways of mark making can be experimented with much in the same manner as drawing, particularly pen and ink techniques.

If the final image is to have tonal elements, then the aquatint process can be used.
Unless working intuitively then artist should have either a working sketch, coloured line proof or a good idea of the image wanted. This working sketch or the original concept image or drawing is useful to refer to during the aquatint process.

10. Aquatint
  1. The plate is cleaned with turpentine, methylated spirits and chalked and dried as described previously
  2. Liquid hard-ground is brushed onto plate wherever there is absolute white in the concept image
  3. This process is called blocking out, blocking out the acid solution
  4. The first spray of liquid hard ground can be applied now, it can really be applied before first block out for white
  5. Once the spray is dry...
  6. The metal plate is immersed in an acid solution appropriate to its type, for a length of time
  7. The plate is removed from the acid solution and thoroughly rinsed in water
  8. A second spray in applied
  9. The first shade of 'gray' is now blocked out anywhere on the plate that this ''gray' appears in the concept image
  10. The metal plate is immersed in an acid solution appropriate to its type, for a length of time
  11. The plate is removed from the acid solution and thoroughly rinsed in water
  12. A third spray in applied
  13. The second shade of 'gray' is now blocked out anywhere on the plate that this ''gray' appears in the concept image
  14. The metal plate is immersed in an acid solution appropriate to its type, for a length of time
  15. The plate is removed from the acid solution and thoroughly rinsed in water
  16. More sprays can be applied as one see's fit, but three is considered adequate
  17. Of course be sure not to entirely block the plate out
  18. The third shade of 'gray' is now blocked out anywhere on the plate that this ''gray' appears in the concept image
  19. The metal plate is immersed in an acid solution appropriate to its type, for a length of time
  20. The plate is removed from the acid solution and thoroughly rinsed in water
  21. This cycle continues until only the utterly black tonal areas are still open to etching
  22. Once black has been etched then...

11. Time to proof the plate again, or for the first time...
  1. Hard-ground is removed with turpentine and a rag
  2. Oil from turpentine is removed through applying slurry of chalk and acetic acid again
  3. Plate is thoroughly rinsed and dried
  4. Plate should be ready to ink up and proof

Amount of time the 'sprayed plate' remains in acid solution determines depth of bite, and depth of tone. The longer in the solution the darker the tone will be.

So the lightest gray tone would have been blocked out after it was etched for 15 seconds
The next darkest gray would have been blocked out after 30 seconds of immersion

SCROLL TO TOP