Ways of print
Lenticular print can be done with virtually all techniques. Regarding resolution certain techniques are connected with certain pitch of lenses: large size ink-jet 6-50 lpi, offset 75-200 lpi, flexography 10-200 lpi, seriography 10-40 lpi, digital photography 10-40 lpi. Two ways of print exist.
PRINT ON MATERIAL AND ITS LAMINATION ON FOIL
It is used for home or small-lot production through the use of photoprinters and ink appliencies or when postcards with printing on reverse side, lenticular stickers etc. are made. Digital methods give great results but limiting factor is volume of finishing work and resolution of output device which ranges from 200 to 1140 dpi. For example 75 lpi lens with 12 frames requires print resolution 900 ppi according to formula: lpi x number of frames = pixels per inch. If the device is not capable of this, grid is multiplied by coefficient 0.5 or 0.75.
It is possible to print on almost every colour printer – if it is not stated in manual, an information that it prints on non-porous mediums helps.
The best for printing is white film medium polyester-based because is not temperature and humidity extensible ( DuPont Melonex is recommended). Good results give also ordinary UV or water-free printers.
All ink and bubble printers print better faceing movement of head (i.e. 1440 dpi) than faceing mechanic drive of material (i.e. 720 dpi). Accordingly is the image directed so the lens is situated upright to direction of the head. For best results is recommended to decrease speed of print heads that slows the production thoug but colours are vibrant and overlaped. Also help fourfold transit and unidirectional print.
DIRECT PRINT ON LENTICULAR FOIL
Printing on reverse side of the lenticular foil is the most common method (90% of production in the world).
Limiting factor with offset machines is thickness of material that does not commonly rise above 0.035´´. Because thickness of lens relates to its pitch (6 lpi = 0.185´´, 45 lpi = 0.045´´, 50 lpi = 0.032´´, 200 lpi = 0.01´´) for offset are applicable from 50 lpi up.
Colour register with one another and with span of lens must stay in range of thousandth of inch. Special position of grid is used to avoid moiré, min. lineature 300 lpi, min. resolution of ?...? 2540 dpi. Stochastic grid is close to photograph resolution and gives the best results.
Calibration and preparation are complicated and tedious so that offset production is rentable from high printing (min. 5000 pc).
Prices of lenticular prints follow similar curve of price/quantity ratio like other printed matters but in low volume area is much more steeper because the preparation is more demanding.
Size plays important role. The material is far more expensive than paper and small increase of sheet cause big increase in costs.
