Making photopolymer plates in the Art Department Print Lab at UCSB

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1 Making photopolymer plates in the Art Department Print Lab at UCSB Preparing images and text Submitting files to a service bureau to have a negative made Processing photopolymer plates Preparing images and text Digital images most commonly come from a digital camera, a scan, or online. It is possible to use images from the web, although many are too small to give good results. Turning images into Halftones The quality of the halftone you produce will reflect the quality of the image you start with. A good black and white photograph will probably work better than one with bad exposure and tonal range. If you use a poor quality source image, you can t expect it to produce a very good halftone. Recommended scanning resolution is double your intended halftone resolution. (Scan at a minimum about 170 dpi if you are making a negative with a halftone resolution of 85 lpi.) There are several adjustments that you can now make to your image that may improve the quality of your halftone. Using the levels Adjustment works well for this. Image: Adjust: Levels Convert the image to a halftone after you have made all adjustments to your image, because many of them can t be done in bitmap mode, and scaling an image that is already a halftone will scale the size of the dots, changing the halftone resolution. Image:Mode:Bitmap Output Resolution: 1200 Method: Halftone Screen Frequency: 85 lpi. For Images that aren t continuous tone, like Lineart, choose 50% Threshold (instead of Halftone Screen) from the drop-down menu. If you are going to scale your image up, use this equation: final image height original image height X halftone resolution X 2 = minimum image resolution

2 If the output resolution on the printer isn t set high enough, the halftone image will be posterized. Scanning lineart and text When scanning lineart or text, You want to capture as much detail as possible. Try scanning at 1200 pixels per inch. Setting Text Many different kinds of software can be used to generate text. Our instructions are focused for using Illustrator or Indesign. They allow for more typographic control than Photoshop, Microsoft Word, or Open Office. Photoshop s typesettting capabilities have improved with newer versions of the software, but it is still best suited for image manipulation. Create outlines of all type, or include the font folder(s) that you have used in your job when necessary. Putting it all together to send to the service bureau Multiple images can be laid out on a single negative, but they should be separated from each other by a minimum of one inch and should be aligned for linear cuttings in either direction. Unless it is integral to your design, the lineart, halftones, type, solids, and reverses should be grouped separately from each other. You will eventually make separate plates (with different exposure and washout times). Using the labs on campus Bring appropriate flash drive, portable harddrive, or burnable disk. To scan on campus(mstudio, estudio, Phelps, Kerr) check in with the appropriate lab monitor before initiating the scan.

3 Service Bureaus Our top recommendation is Graphic Traffic, 622 Olive Street, Santa Barbara. (805) website: graphtraff.com. This company has worked with Art Department classes in the past. Art students visit there regularly, and they are familiar with our use of negatives for photopolymer. Here are their most recent instructions to us: Our hours are M-F 8am-5pm. All pick ups must be made by 4:45 pm. Sending Files Digitally Include all necessary files in one folder. Be sure to Stuff or Zip this folder: on a Mac, ctrl click>create Archive of example folder on a PC right click>send To>Compressed (zipped) Folder **Please encourage students to make a PDF- it s our preferred file format! This way we don t have to worry about missing links and fonts. Please avoid JPEG s! File Notes: Grey scale format for black and white images bit-mapped if need be Make sure files are clean of speckling. Any residue from pencil marks or erasers WILL show up on your film. Uploading Files: go to www. graphtraff.com go to Upload Your Files on left hand side fill out the requested information and follow the steps to submitting your file(s) *make sure to specify the service requested: film negative for polymer plate, 1800 resolution, emulsion up, 85 line screen. *make sure to include contact information! Files under 10 MB can be sent as an attachment via to: imaging@graphtraff.com Files up to 100 MB can also be uploaded to their idisk account: on a Mac Go>iDisk>other users idisk Member Name: gtsb (case sensitive) Password: publish (case sensitive) Drop the archived or zipped folder in the public folder Other places may be able to make negatives too: search for Computer-Service Bureaus, and Electronic Imaging. These companies use a process known as high resolution imagesetting, also called Linotronic output. Dots per Inch (DPI), Lines per inch (LPI) and Pixels per Inch (PPI). Turn Around Time: Our usual turn around time for film is about 4 hours. Film will be ready for pick up by 4:30 if problem free files are submitted before 12:30pm. Files submitted after 12:30pm will be ready for pick up the following day by noon. You are welcome to call us and check up on the status of your job.

4 Processing the Photopolymer Plate The plate material is UV photosensitive and when exposed to an ultraviolet light through a high contrast negative, the UV cross links the polymers and hardens the image. The unexposed portion of the plate is washed off in plain water, dried and post exposed. the plate is ready for the press in less than thirty minutes. To print letterpress you will expose the plate with a negative. Our plates are metal backed and come in a few different sizes: A4 (11.7 x 8.3 ) $18 A5 ( ) $9 A6 ( ) $4.50 Sometimes we also have: A3 ( ) $36 Negatives Imaging for polymer plate processing should be in the form of negatives, with the emulsion side up and right reading (RREU). The preferred negative material is a high-quality matte base lithographic film with high contrast between the matte and glossy sides. In the exposure process, the emulsion side sticks to the polymer plate surface. A matte surface facilitates proper vacuum drawdown, thus achieving full contact with the plate. Negatives should be free of chemical residue, surface dirt, smudges, scratches, and kinks. Cutting The Plate Unwrap and cut the plates in subdued light. The board shear with the wooden top can be used for cutting polymer plates, but do not cut any other metal on the board shears. Cut plates after your negative has been inspected. Make the negative slightly smaller than the plate. Exposing The Plate 1. Turn the power switch on at least minutes before you plan to use the unit. The water temperature should at least rise to degrees. 2. With the light dim, peel off the plastic protective sheet on the unexposed plate. File and flatten all sharp or bent edges of the plate. 3. The negative should be smaller than the polymer plate. Place negative on polymer plate, with emulsion side down. This way the image should read in reverse, the way it will form on your plate. 4. Position the polymer plate and negative under the krene. Overlap the krene to form a vacuum. The vacuum reading should go to maximum, near the 25 mark. If this does not occur, you haven t formed a good vacuum. Protect the edges of the plate as instructed. Keep the krene clean and unwrinkled. Smooth out air bubbles (if any). 5. With a tight vacuum, close the drawer. Select the proper exposure time. Follow this guide: a. 3 minutes for solids and reverses (with true negatives) b. 3.5 minutes for type (with true negatives) c. 4 minutes for half-tones (true negatives) 6. If you have to expose type and half-tones on the same plate, you may want to expose one element of the negative longer than the other. If you do this, work in two steps: expose the full plate for the minimum time; wait until the exposure time is complete, then add a mask to go over the element that is exposed for less time. Do not open the exposure unit while the light is on. Washout Do not try this procedure unless you have been given step-by-step instruction by a qualified instructor or lab

5 monitor. Place exposed plate on magnetic base. Use polyester strip under plate for easy lifting. Keep lid in up position at all times except when washing out. Remember that the washout time is indicated in total seconds. Washout time should be from 1 to 6 minutes; in general, it should be approximately the same amount of time as exposure. Check washout periodically. Drying the plate We usually dry plates for 10 to 15 minutes at 150 degrees. Use the platemaker s drying unit. This process can go on while other procedures are taking place. Post-exposure Carefully set your dry plate on the krene; no vacuum is necessary. Post-exposure rates are set to the same time or longer than the initial exposure time. We recommend a post-exposure time of twice the original exposure. Other stuff Scanning a monochrome halftone There are two ways to approach scanning an image that is already a halftone: 1. The image can be scanned in greyscale, despeckled, adjusted for size and tonality as in the process above, and re-screened. A re-screened image has two screens overlapping each other, which causes moire patterning. Filters such as despeckling(filter: Noise: Despeckle) or gaussian blur can help to virtually remove the screen from the original image, which will cut down on the moire effect. 2. You can use the dots of the original halftone by scanning it like lineart. This method preserves the original halftone.