Prepress for FinePapers
美術紙的印前打樣 / Prepress for FinePapers
樣品是Arjowiggins Creative Papers賀卡，印刷在Rives Sensation Matt Tactile High White 350g 和 Conqueror CX22 Brilliant White 100g上，由倫敦的North工作室設計，為了選擇最適合多種項目的印前打樣紙張，首先進行UV印刷測試(Curious Cosmic, Curious Metallics, Rives Sensation…)，經過初步測試，能夠得到更加完善的打樣數據資料與期望的印刷效果做配合，第一個步驟是四色印刷，其次是熱燙和壓印，主要挑戰是確保壓印和印刷區域間的完美重合。
The sample is Arjowiggins Creative Papers’ greeting card, printed on Rives Sensation Matt Tactile High White 350g and Conqueror CX22 Brilliant White 100g. The design was developed by London-based design studio North. Numerous print tests were first conducted in UV-Offset in order to choose the paper stock best suited to the project (Curious Cosmic, Curious Metallics, Rives Sensation…). Thanks to this trial step, the studio was able to best define the prepress profile matching our print rendering expectations. The first production step was 4-colour offset printing, followed by hot foil and finally 2-level embossing. The main challenge was to ensure perfect registration between the embossing and the printed areas.
Prepress is the necessary step between the creating of a design and the making of the plates for printing. This step is crucial to get the printing right, and should be done by a prepress expert during design and if possible reviewed by a prepress operator at the printers. The artwork, the desired print rendering, the printing technique and the paper stock all need to be considered at this stage of the prepress process.
- DO vectorize your files as much as you can. The vectored design is the safest method for ensuring the design layout is not changed through the prepress conversion.
- DO use under colour removal (UCR or GCR) for dark 4 colour images with higher ink density in order to obtain quicker drying times and reduce risks of ink rub and set off.
- DO name layers clearly when using spot colours, UV varnish, H-UV varnish, foil or other printing techniques in addition to offset printing. Be as specific as possible and also think about naming properly any special spot colours used.
- DO consider the type of paper stock you will be printing on. From coated to uncoated paper or smooth to textured papers, the dot gain will vary so you need to take this into account before converting your files.
- DO provide your printer with a hard copy proof of your design at 100% scale along with your files.
- DO always check with your printer that your document has been properly set up during prepress and ask him to make its hard copy proof before printing.
Offset and digital printing combine colour separation (usually CM Y K, plus spot colours) with screening (converting a continuous tone image to an image made up of tiny dots), to create thousands of colours, shading and colour gradations. Whether process or spot, inks will sit differently on uncoated papers, and require special adjustments during the prepress stage.
- DON’T bypass the basic prepress steps, from creating the bleed, trim marks, registration marks and colour bars, to ink trapping and getting fonts and images right.
- DON’T plan the Total Ink Film Weight higher than 280% on uncoated papers. Having high ink film weights leads to problems such as ink marking, ink rub and drying problems.
- DON’T print thin or small text out of 4-colours, instead consider a special colour to avoid misregistration.
- DON’T forget to prepare the file in accordance with the printer’s specifications. Especially with stochastic screening, the printer will need to give you detailed information for you to prepare the file properly.
- DON’T neglect the effects of different blacks. There are many blacks having variable density and warmth that will look very different when printing solid areas.