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.

 

建議事項
打樣是設計與印刷製版之間的必要步驟,盡可能在設計時讓印前人員審查操作,需要的印刷效果、印刷技術及紙張都需要在印前階段時考慮。

  • 盡可能矢量化檔案,保證檔案在印前轉換過程中不發生改變的安全方法。
  • 使用底色去除(UCR),或灰成分替代(GCR)可節省彩色油墨的用量、加快油墨的乾燥時間及降低油墨摩擦與點燃風險。
  • 在平版印刷中使用特殊色時,請清楚具體的命名各圖層。
  • 考慮將印刷的紙張類型,從塗佈到非塗佈紙或紋理紙的網點會有所不同。
  • 檢查印刷機以確保檔案在打樣時已經正確設定,印刷前索取紙本打樣。

注意事項
四色印刷及數位印刷結合色彩分離(CMYK及特殊色)和網點,創造出數以千計的顏色,明暗及色階,無論是CMYK或特殊色,油墨在非塗佈紙上會有不同的覆蓋結果,在印前階段需特別調整。

  • 不要省略基本的印前步驟,設置出血、裁切標記、對齊標記、色彩導表、油墨疊印、字體及圖像版權。
  • 總油墨量若高於非塗佈紙的280%,會導致油墨有摩擦、乾燥等問題。
  • 為避免位置偏移,使用特殊色進行印刷而非四色印刷。
  • 根據印刷機的規範設定印刷檔案,特別是亂數網點(FM調頻網點),印刷機將需要提供精細的資訊給印刷檔案。
  • 不要忽略不同黑色油墨的影響,許多黑色油墨具有可變的密度及溫度,印刷固體區域時會有非常不同的效果。

 

DOs
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.

DON’Ts
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.

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