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Exploring Ferric Chloride Etching

The ethos of paper-works* is to use low tech, low impact techniques so we were immediately drawn to avoid the strong acids, organic solvents etc used in traditional etching processes . Reading around the subject the use of a Ferric Chloride solution to etch copper plates seems like the way to go.

Advantages of ferric chloride

Ferric Chloride has immediate advantages. It is a salt rather than an acid. It is a less noxious chemical to have in the studio than an acid. However it still needs to be treated with care!. Also when etching copper it produces no gaseous by products so fume extraction is not an issue. It can also produce a good quality clean etch. However it has suffered a couple of drawbacks which has limited its use historically as an etching medium. Namely the slow speed of etch and the way that the sludge that develops as a by product can inhibit the etching process.

At its simplest a copper plate can be etched in a shallow tray of a ferric chloride solution. Occasional agitation of the tray will help move the sludge out of the way of the etching process. The etch can be achieved but it is slow. The slowness of the etch increases the chances of breakdown of the resists used in the etching process resulting in etching of the copper plate in areas that it is not wanted.

A better etching tank

Electronics enthusiasts have used ferric chloride as a means of etching copper circuit boards for many decades. Their approach to improving the etching process has been to develop vertical tanks rather than horizontal trays and to equip them with aquarium style air bubblers to provide constant agitation and aquarium heaters to speed up the etching reaction. We have looked at a number of such tanks and opted for the “Velleman ET20 etching tank” which complete with air bubbler and heater can be purchased for as little as £90. It is capable of accepting plates up to 300mm x 200mm.

Ferri chloride etch tank

A better etching solution

Printmakers have meanwhile adopted a differing approach to improving ferric chloride etching by experimenting with the solution itself. The result has been the “Edinburgh etch” a combination of controlling the strength of the ferric chloride and adding citric acid to obtain an etching solution which both acts faster and minimises the production of sludge.

To progress our experiments we have decided to go for the combination of the improved tank system tank and the improved etching solution.

Acrylic resists

The other element in copper plate etching is of course the resists being used. Again our desire for a low tech, noxious free approach led us straight to acrylic based resists. Acrylic resists can be quite simple from the use of acrylic based floor varnishes to a variety of proprietary acrylic resist systems. For our initial experiments we have opted to test Lascaux acrylic resists which come in a wide variety to provide hard ground, soft ground and aquatint style formulations. The full set are obtainable as a relatively modestly priced boxed set of nine 85ml bottles obtainable for around £60.

Chemical Disposal

Edinburgh etch solution is reported to remain potent for up to a year even with regular use but at some point it will need to be replaced. Unwanted Edinburgh etch should be disposed of appropriately. The following advice was obtained from MG Chemicals website

“The solution must not be put down the drain because of residual copper ions left in it. To make it safe for disposal, you can add sodium carbonate (washing soda) or sodium hydroxide to it to neutralize it, until the pH value goes up to between 7.0 and 8.0, testing it with indicator paper. Copper will be deposited as a sludge. Allow the sludge to settle, pour off the liquid, further dilute it with water and then it can be poured down the drain. Collect the sludge in plastic bags and dispose of it as required by your local waste authority”.

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Pinhole Cameras on the Market

There are a wide range of pinhole cameras available on the market. They can be a useful guide to selecting appropriate sizes of focal length and pinhole size for making your own. Here is a selection grouped together by the size of the film/paper.

8″ x 10″ 

Zero 810, 80mm focal length, 0.35mm pinhole

Zero 810, 160mm focal length, 0.5mm pinhole

ONDU, 130mm focal length , 0.5mm pinhole

Lensless Camera Co. 150mm focal length, (pinhole dia unknown)

5″ x 7″

ONDU, 97mm focal length, 0.4mm pinhole

Lensless Camera Co. 125mm focal length, (pinhole dia unknown)

4″ x 5″

Ilford Obscura, 87mm focal length., 0.35mm pinhole

ONDU 65mm focal length, 0.35mm pinhole

Lensless Camera Co. 75mm focal length (pinhole dia unknown)

Harman Titan 72mm focal length, 0.35mm pinhole

120 Film, 2 3/8″ x 2 3/8″ 

Nopo 120, 35mm focal length, 0.25mm pinhole

ONDU 6×6 25mm focal length, 0.2mm pinhole

35mm film

Zero 135, 25mm focal length, 0.18mm pinhole

Lerouge 26mm focal length, 0.2mm pinhole


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Make your own Pinhole Camera

A brief guide to making your pinhole camera, taking your photo and developing it!

Not sure what pinhole photography is then read this

You will need:

General Materials: a light tight container, black paper or paint, aluminium foil black electrical insulating tape.

Tools:  a pin or a fine 0.3mm drill, knife/scissors/ paint brush, a measuring jug.

Darkroom:  Any room where you can successfully provide full blackout . A photographic darkroom safelight, 3 shallow trays a bucket of water and a length of chord and some clothes pegs to allow your prints to dry.

Photographic chemicals:  ( Harman Direct Positive paper, Neutol Eco Developer, Citiric acid, Adofix plus Fixative.

Optional extras: Pinhole Master for IOS  or Pocket Light Meter (iOS & Android)

Making your pinhole camera

1) Select a light tight box or tin

2) Use black paint or black paper to cover internal surfaces of container to minimise reflections.

3) Create your pinhole. If using a tin use a 0.3mm micro drill bit in a small hand held modelmakers drill. If using a cardboard box make a hole in a piece of aluminium foil with a pin or small needle. Then use black insulation tape to stick the aluminium foil over a small hole cut into the box.  ( NB after making your hole use a small piece of emery paper to remove any metal burr from the reverse side.

4) Make your exposure control using a small flap of cardboard using Black insulating tape as hinge and a separate piece to act as a means of securing your exposure flap in the closed position.

5) Choose how you will secure your photographic paper in the camera. It can be as simple as strips of self adhesive tape or use some card to make some retaining slots that you can slide your photographic paper into.

6) On our courses we have chosen to use Harman Direct positive paper. This is a black and white paper which avoids the need for an intermediate film negative. The ISO speed of the paper is about 1 to 3.

6) Go into your darkroom and using a low wattage photographic safelight put a single sheet of photographic paper into your camera. ( keep your paper at least 3feet from your safelight to avoid fogging the paper) Make sure that you put the paper in the right way round. (Most photographic papers have a glossy coating on the light sensitive side).

7) Before leaving the darkroom make sure that your exposure control flap is securely closed and the box is light tight. Use black insulating tape to seal up any opening edges.

Taking your pinhole photograph

1) Set up your pinhole camera so that it is pointing at the scene you wish to photograph. Avoid trying to hold it steady yourself as the exposure times are long and you will inevitably blur the image . The angle of view of your camera will depend on the shape of the box and in particular the size of the photographic paper and its distance from the pinhole. Once you have taken your first photo you will get an ida about how to arange your camera.  (The likelihood is that the pinhole camera will capture a much wider angle view than you at first anticipate )

2) Getting your exposure time right can be by

a) Trial and error!

b) Rule of thumb guides or

c) pinhole exposure apps.

Rule of thumb guides that come with Harman Direct positive paper suggest the following:

Bright sunshine  (summer) 1-2 minutes

Bright but not direct sunshine  3 minutes

Overcast (mixed sun/cloud) 5 minutes

Dull /Cloudy 6-10 minutes

Interior lighting1 hour

Pinhole exposure apps such as Pinhole Master (ios only) will require you to calculate your Camera’s aperture number . This is simply the focal length / pinhole diameter. The focal length is the distance from your pinhole to the photographic paper. ( where focal length is 45mm and the pinhole diameter is 0.3mm then the Aperture is 45/0.3 = 159. This is often expressed as  f/159.

Using this aperture figure and the ISO number of the paper (1-3) you can create a camera setting for your pinhole camera and then the app will be able to use your phones camera to take a reading of the brightness of your scene and give you a suggested exposure time a countdown timer to take the exposure and also log  the scene brightness imag , the date , time , exposure and the GPS co-ordinates !

3) Once exposure has your exposure flap and take your camera back to the darkroom.

Developing your pinhole photograph

1) Set up your darkroom with 3 shallow trays ( Develop , Stop and Fix)  and a bucket of water!

2) Mix up your developer ( On our course we use Neutol Eco Developer ) This is diluted 1 part developer to 4 parts water . We find 100ml of developer and 400ml of water making 0.5litre of developing solution is a good amount.

3) Mix up your stop bath ( On our course we use Citric acid ) This is made up with 5g ( about 1 teaspoon) of citric acid powder to 500ml of water.

4) Mix up your fixative  ( On our course we use adofix plus ) This is diluted 1 part fixative to 9 parts water . We find 50ml of fixative and 450ml of water making 0.5litre of fixative solution is a good amount.

5) Under safelight conditions take the photographic paper out of your pinhole camera.

6) Place into Developer tray and gently agitate for 90 seconds. You will see the image begin to form after the first 10 seconds or so.

7) Remove paper and place into stop bath for 10 seconds.

8) Then transfer into fixative tray for 60 seconds.

9) Transfer to bucket to wash for several minutes and then allow to dry.


Read about the history of pinhole photography.

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A (very) brief history of pinhole photography

5th century B.C.

Chinese scholars discovered that light travels in straight lines. The philosopher Mo Ti recorded the formation of an inverted image with a pinhole.


Drawing by the astronomer Gemma Frisus’ De Radio illustrating the principal of the pinhole camera. He used the pinhole in his darkened room to study a solar eclipse.

16th Century

Leonardo da Vinci  gave a clear description of the principals of the pinhole camera in his notebooks: “When the images of illuminated objects pass through a small round hole into a very dark room…you will see on paper all those objects in their natural shapes and colours.”

1822 to 1839

Development of the first light sensitive processes for capturing images . From Joseph Nic Ophore Niepce in Sir John Hershel in 1839.


Sir David Brewster is believed to make some of the first pinhole photographs. He wrote about it in the1850’s in his book “The Stereoscope” It was the first time that the word “pin-hole” was first coined.


Flinders Petrie, a prominent archeologist took many pinhole photographs during his excavations in Egypt.


Lowestoft born photographer George Davison exhibits “The onon field” a pinhole camera photograph in the 1890 exhibition of the Royal Photographic society . This led to a brief period of interest in the technique. Following a brief flourishing of the commercial production of pinhole cameras the technique largely disapeared in the early 20th century except for educational interest.


Several artists, unaware of each other, began experimenting with the pinhole technique – Paolo Gioli in Italy, Gottfried Jäger in Germany, David Lebe, Franco Salmoiraghi, Wiley Sanderson and Eric Renner in the USA.


Jim Schull publishes “The Hole Thing: A Manual of Pinhole Photography a paperback book which popularised the technique and remains a valuable resource today.


On the 29th of April the first World Pinhole photography day was held.


Read how to make your own pinhole camera

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Strong 20 micron aluminium foil for Kitchen Litho

We have found that our success rate with avoiding damage and tears to the aluminium foil during inking up has been much improved by using thicker aluminium foils. Most domestic aluminium foils are around 8 to 9 microns thick but some commercial or BBQ foils are much thicker. We have successfully been using a 20 micron Aluminium foil that we found on amazon. The details are as follows:


Testudo Alu Foil, Catering Foil, 30cm x 45m, 20 micron

£8.99 including free UK Delivery.

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Fabriano Unica Printmaking Paper

Our current favourite paper at Paper-works* for most printmaking is Fabriano Unica paper. It is made of 50% cotton, and has been specifically developed to be suitable for all printmaking techniques. The paper is a combination of the many years experience of the Fabriano paper mills and a collaboration with a group of artists from the Opificio della Rosa , an international centre dedicated to the awareness and spread of traditional and innovative methods of printmaking.

The artists from Opificio della Rosa have tested the paper with a host of printing, engraving and other techniques, testing it to its limits. The paper  has a weight of 250g/sqm and is economically priced and available in white and cream in three different sizes: 50cmx 70cm , 56cm x 76 cm and 70cm x 100cm.

Paper-works* has been successfully using Fabriano Unica for Linocut, Drypoint, Kitchen Litho and Cyanoprint.

Individual sheets of Fabriano Unica are available for purchase from paper-works* by those attending workshops or members open days.

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Cyanotype Printing

Cyanotype test strips

Cyanotype Printing

Cyanotype printing is a method of image making on light sensitive paper. Unlike most photo sensitive techniques it utilises iron rather than silver based salts. It is characterised by the blue and white prints that it produces,(known as “blueprints” when used to reproduce technical drawings).

The process was invented by Sir John Herschel in 1842. His invention was initially principly taken up by botanists for the purposes of plant specimen illustration, notably Anna Atkins. Following Herschel’s death in 1871 the process was “reinvented’ and used principally as a reprographic system particularly for technical drawings up until the 1950’s. Interest in cyanotype as a photographic printing medium has grown again since the 1970’s to the present day.

Exposure times are relatively slow and the chemicals require exposure to light in the ultra violet spectrum. The long exposure times and high light levels required mean that it isn’t considered suitable for use in cameras but is instead primarily used for contact prints from negatives or direct from objects placed on the paper (photograms). Strong sunlight is an ideal light source but UV bulbs can be used as an alternative.

Preparing the photosensitive solution

The exact recipes for the photosensitive solution have varied in some respects over time. The following is a typical 20th century recipe.  Precaution:Use disposable gloves and a face mask whilst handling the powdered chemicals.

Add 25g of Ferric Ammonium Citrate to 100ml of water in a glass container

Add 10g of Potassium Ferricyanide to 100ml of water in a second glass container

The chemicals dissolve readily in cold water and are not light sensitive until they are mixed together. You will need some small electronic scales to measure the chemical quantities.

(Chemicals can be purchased from Silverpoint ( )

Coating your paper

You will then need to move into a photographic darkroom with a safelight or a darkened room with very low level tungsten lighting. Add each of the solutions into a third container. To enable storage of the liquid its best to use a dark brown glass jar with a light tight lid. Stir briefly to ensure both solutions have mixed together.

Now use a brush to apply the light sensitive solution to your paper. A foam brush works well. Then return any unused liquid to the dark brown storage jar and set aside your paper to dry in full darkness.( NB For longevity of the Cyanotype print its best to use a “non buffered” paper i.e. one that hasn’t had chalk/calcium carbonate added to increase its alkalinity)

Once dry keep the paper in a light tight black plastic bag or a light tight cardboard roll until required for use.

Exposure to direct Sunlight

On a bright sunny day prepare the objects, masks or drawings on acetate/tracing paper  that you want to use to create your image and get a clock or watch to hand so that you can keep an eye on the exposure time.

Remove the paper from the roll spread out in direct sunlight with the pale yellow side uppermost. Immediately work quickly placing your objects on the paper. Items placed immediately will leave white marks. Items placed later will leave marks which are  very pale blue progressively getting deeper, the later that they are placed. Areas left in full sun will be a deep blue with 3 minutes exposure to the brightest UK sunshine.

When 3 minutes is up quickly move the objects aside and put the paper back in its black plastic bag or light tight cardboard roll.

( Its useful to have created several long strips of cyanotype paper that you can use as exposure test strips , use some dark card and reveal more of the strip each 15 or 30 seconds in order to get an accurate idea of exposure times for your particular lighting conditions)

Exposure using UV Lamp

In the absence of strong sunlight its possible to use a UV floodlight to expose cyanotype. Exposure times are longer than with sunlight. A 40W LED UV floodlight mounted about 2 feet above a worktop will expose cyanotype paper in about 10 to 15 minutes.

If your work room is lit with subdued daylight then the advantage of using the UV floodlight is that you can spend much longer composing the items that you are placing on the cyanotype paper before you switch the UV lamp on and start the exposure. Its still best to store the cyanotype in a light tight container or envelope  when you are not using it to ensure that it isn’t degraded.

( If you make a UV lamp exposure strip then try using minute intervals between 10 and 15 minutes as a starting point )


In subdued light conditions take the exposed cyanotype out of its light proof container and immediately immerse in a tray of cold water. agitate gently for several minutes. The cyanotype will reveal its characteristic cyan colouring and the water will colour slightly. Change the water for a final rinse of another couple of minutes allow excess water to drain off then place the print between two sheets of blotting paper and place under a weighted plywood board and allow to dry flat over a day or so. ( NB longevity of Cyanotype prints is increased with thorough rinsing but this should be balanced against dispersion of the blue colouring that may occur with rinsing)

Longevity of Cyanotype prints

Cyanotype prints made by Anna Atkins in the 1840s are still in existence. However some care is required for their longevity. To minimise fading of the image  take note of the following:

  • Avoid permanent display in daylight (returning prints to darkness can reverse some colour loss)
  • Rinse we’ll during processing to reduce presence of any remaining photosensitive solution or other impurities.
  • Avoid use of buffered papers ( i.e. papers incorporating chalk or calcium carbonate)
  • Do not over agitate or use fast running water during rinsing to minimise dispersal of the blue colour
  • The chemicals used in cyanotypes, and the use of non buffered ( i.e. neutral or slightly acidic) paper can result in brittleness of the paper substrate over time.

Read details of our next Cyanotype course.

Download Mike Ware’s authoritative book on Cyanotype









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Pinhole Photography | what it is | a brief guide

Pinhole Photography

Pinhole photography is the term used to describe photography executed without a lens. Instead it uses the camera obscura effect where an upside down mirror image is formed on a surface in a darkened space by light passing through a small pinhole from an external scene.

Film and photographic papers

Pinhole photography can be executed onto standard photochemical film which is then processed in the normal way and prints can then be made with an enlarger. However the ability to cheaply make large format pinhole cameras makes it suitable for the creation of images directly onto black and white photographic paper. With standard photographic paper the developed image will be a mirror and a negative image. This image can be reversed by taking a contact print using a second sheet of photographic paper. The end result will be a  positive image which is also the right way round. Alternatively you can use special direct positive photographic paper. This will result in a positive image in one exposure but it will however still be a mirror image.

Pinhole cameras

One of the best things about pinhole photography is that you don’t need an expensive camera, in fact you don’t need a camera at all ! A lightproof container , a pinhole and a sheet of photographic paper is all you need!. You can use any old box, paint tin , old wardrobe, garden shed or almost anything as a pinhole camera.

Photographic results

Exposures can be worked out (a bit) but mostly its a good amount of trial and error.  The photographs that you get from a pinhole camera are very governed by the size and geometry of the light proof container you have chosen, the pinhole size, the length of the exposure and the distance from the pinhole to the photographic paper. One thing you don’t have to worry about is focussing! No lens means no need to focus , everything is in focus, you have an infinite depth of field!

The crudeness and the visual distortions of the images are all part of the pleasure of pinhole photography, something to be embraced and exploited rather than something to try and design out. It is of course possible to adapt high end digital cameras to take pinhole images but it is perhaps missing the point. Pinhole photography is not just about the technical use of a very small hole rather than a lens to create an image. It is an invitation to embrace a fun low tech way of exploring how to create photographic images !

Read about Lowestoft’s own pinhole camera hero






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Drypoint card : Exploring its use for Intaglio printmaking.

Drypoint card

We have spent some time today making drypoint images using  drypoint card rather than the usual clear plastic. The drypoint card we are using is sold by Intaglio Printmakers in London. It is a medium thickness dense white card with a thin plastic coating on the printing surface.

We tend to use the drypoint plastic more as we like freely drawing using a tool as one would with a pencil or charcoal. Repeated loose lines can build up on the plastic easily and can give the effect of a spontaneous drawing. However we had decided it was time to explore different techniques. We had already spent an hour or two the other day exploring marks  with different tools and also blocks of ink that can be made by removing sections of the laminated card.

After doing a couple of still life drawings of household objects we began to feel a bit more at home with the material. Overall we found that we could retain a natural drawing style pretty easily on the card and we like the possibilities that the card provides that plastic doesn’t, namely the option of removing a blanket area to give a blacker inked space and the dense dark lines than can be achieved in the relatively soft card surface.

To join us on an upcoming Drypoint course see available dates.