Photopolymer in emulsion

Manual written for Polymetaal, Leiden by Wouter Ferro Wouter 2012 Info via Polymetaal

Quick guide:

  1. Degrease the metal plate.
  2. Apply a thin layer of photopolymer emulsion with a roller.
  3. Harden for ½ hour at 60 ° C or more and then at room temperature for 1 hour.
  4. Expose to UV
  5. Develop in soda (5 grams per liter) for about 1 minute and test if metal is open.
  6. Harden with UV exposure.
  7. Etch in FeCl (ferric chloride) or other suitable medium.
  8. Strip with soda (100 grams per liter). This solution is also good for cleaning tools.

    More details below.


This emulsion is suitable for rolling up or possibly brushing on a metal plate and then exposing the image for etching into the metal. In that sense, it can serve as a substitute for a thin photopolymer film. This photopolymer is not suitable for doing "intaglio-type", in which only "etching" is done in the photopolymer layer and not in the support (metal plate). This is in contrast to films such as Imagon, Z * Acrylic and DK3 films (due to their thickness of about 50 microns). The emulsion is supplied as a blue, viscous liquid in a 200 g or 1000 g pack in a plastic jar. Because the material is UV sensitive, it must be stored in the dark. Handling is not possible in daylight, but in artificial light, such as fluorescent (because this contains no UV), but try to keep this as short as possible.

Preparation of the plate::

The substrate must be well-degreased and free from oxides. Because the metal is etched, a polished surface is desired. Therefore, use a polished copper (possibly zinc) plate. If desired, the plate can first be treated with copper polish or the like to be made completely smooth. Clean and grease the plate (normally copper, but other metals can also) with a sponge and soy sauce. Do not use sandpaper or other abrasive materials as the plate will be etched. Rinse with plenty of water. When the water runs completely smooth off the plate, it is degreased. Dry the plate well with paper and / or cloth.

Application of photopolymer emulsion:

Place the clean copper plate on clean paper on a smooth surface. Take a lick of emulsion from the jar with a spatula and place it on a smooth plate (eg glass or hard plastic such as Trespa). If desired, 1-4 droplets of thinner ("Photo Emulsion Reducer", see photo on the right) can be added to make the emulsion less syrupy and mix it with the spatula. Roll out with a good quality rubber roller until a uniform film is obtained. Use this as a depot and continue rolling in 2nd place, creating a thinner film. If it has become even, you can use it to roll up the plate. Ensure an even, thin layer over the entire plate. If necessary, also roll crosswise. Optionally the thinner emulsion can also be applied with a brush. Strive for a thin, even layer

Hardening and storage:

Let the plate dry / cure for ½ hour in a drying cabinet at approx. 60 ° C or more and without light. Then let it cool in the dark and leave it for at least 1 hour. The plate may no longer be sticky. Even after this period it is better not to stack plates. At this stage, plates can be stored in the dark for several days without further treatment. A light-tight box can be useful here.

Cleaning the tools:

Even after drying, the emulsion can be properly removed with a concentrated soda solution of 100 grams per liter or with "Dasty" degreaser (available at Wibra stores). Use cleaning paper or a piece of cloth or a sponge and rinse well. ("Dasty" is quite aggressive, so it is best not to use it as a spray.)


Use a UV source as for other photopolymer products. The emulsion is slightly less sensitive than DK photopolymer film. As a guideline: 50% longer exposure. N.B. It is strongly recommended that you perform test exposures with different exposure times for your own setup. Highlight a transparency with a halftone image. For entirely black parts in the image, a separate exposure must be done with an aquatint screen. Or, alternatively, an aquatint based on acrylate can be applied after development..


Cover the back of your plate with tape or adhesive plastic to protect it from etching bath that follows. Develop the exposed photopolymer in a soda bath of 5 grams per liter. Gently wipe the entire plate with a sponge. The image quickly becomes visible. After about 1 minute the copper is exposed in the dark areas. Stop developing by rinsing well with water. If necessary, for a quick stop, first spray with a little vinegar. To test whether the copper is indeed open, the plate can be held in the etching bath (e.g. ferric chloride FeCl) for a few seconds. Then rinse well and check whether the copper has been bitten. Even a very thin layer of photopolymer can shield the metal. If not open again a short time (try ¼ to ½ minute) in the soda bath. N.B. If developed too far, details of the image will disappear. Then test again in the etching bath. Now the plate can be exposed to UV light to cure the remaining photopolymer. 2-3 x the normal exposure time is sufficient. Leaving some time in daylight has the same effect. If desired, de-oxidize and dry the plate and spray acrylic aquatint. Corrections with a stopout can also be made. Harden any aquatint and stopout in the normal way.


Place the plate in the etching bath for the desired time. This can also be done in phases to continue working with stopout.


Place the plate in a 100 g / l soda solution for a few minutes to remove the photopolymer layer. If necessary, wipe with a soft brush to speed up the process. Rinse well and dry. After this, the copper plate can be printed or further processed with other techniques.

Remarks, problems and possible solutions:

Etching, 2 plates with photopolymer exposed and etched in copper. Then reworked with, line etching. Wouter Ferro, 2012, "Loopje" 5 x 7 cm,

Testing your specific system is strongly recommended. Based on the times, concentrations, etc. given above, you will need to find the right parameters for your system. Household soda and tap water will suffice. Variations in water quality will have an effect, but, for example, layer thickness of the photopolymer and ambient temperature will have stronger effects.

- If in the end result white parts do get a tone: Does the photopolymer layer not cover enough? Apply a slightly thicker layer. Also try to roll crosswise to get good coverage without holes..

- If the photopolymer peels off everywhere during development: Was the plate really well degreased? Was the hardening phase long enough and warm enough? Did the plate lie long enough after the curing?

- If development is very fast: For example, reduce the concentration of soda to 4 or 3 g / l.

- If the photopolymer dissolves everywhere during development: Was the exposure time enough? Was there good contact between transparent sheet with photopolymer?

- If no image emerges during development and photopolymer remains present over the entire plate: Has the plate been in daylight or has it been in some light for a long time?