Using NewsCraft LGN
NewsCraft LGN paper is a specially coated translucent paper designed specifically for printing applications to embody three major characteristics:
- Dimensional stability under heat and pressure.
- Superior toner adhesion and durability.
- Increased transparency, particularity to UV light.
Due to these unique properties, LGN paper has found acceptance in a wide range of applications such as screen printing, sign manufacturing, printing with photopolymer and both positive and negative metal plates, glass and stone etching, circuit board layout, and others. It has been used successfully in both process and spot color applications requiring accurate registration.
Use of LGN paper does not require special computer software and can be used with most MacIntosh and Windows based software. To get the best results with LGN a laser printer capable of producing solid blacks is required. Laser printers manufactured by ColorScan (formerly LaserMaster), Xante, NewGen, GCC, Hewlett-Packard, Apple, Lexmark, and Canon have all been used successfully. This does not mean that other brands of laser printers will not work, only that we have not had direct experience with them reported to us.
Following a few basic guidelines will assure that you get the best possible results with LGN. If you still have problems using LGN please call System Facilities at (315) 234-2348 and ask for LGN User Assistance.
Step 1: Make sure that your laser printer is clean. Carefully follow the cleaning directions included with your printer. Remove excess toner and paper lint that may be in the paper path. A clean printer will produce a more even image.
Step 2: Set the toner density as dark as possible for your printer. You want maximum toner coverage so that the blacks are as solid as possible. DO not be concerned about using extra toner.
Step 3: Keep the LGN paper in a dry environment. An air conditioned workplace is fine. High humidity, such as opening the windows on a rainy day, will cause stretch and toner adhesion problems.
Step 4: When exposing a screen, plate. etc., make sure that the toner side of the LGN is down - against the emulsion on the screen or plate. This prevents light from leaking under the toner and causing blurred edges. Depending on what type of printing you are doing you will need to be able to create either a right- or wrong- reading image In either positive or negative form. In most computer applicators this is usually done in the options item in the Page Setup function by using the Flip Horizontal and Invert option check boxes. Note that some applications, such as Aldus PageMaker 5.0 and Adobe Photoshop, have options called “Make Negative” and “Emulsion Down” which perform the same functions.
Step 5: Exposure times for LGN may vary from film depending on the medium being exposed and the type of lights in use. For screen printing begin by exposing LGN for the same amount of time as you would film. For metal plates start by reducing the burn time by 20%. For photopolymer plates begin by increasing the burn time by 15%. Based on the first test the burn times can be adjusted for best results. If you burn through the toner area reduce the burn time by 10% and try again. If you are not getting hardened emulsion or photopolymer then increase the burn time by 10%. You may have to repeat this process several times until you arrive at the correct burn time for your particular setup. Usually, the adjustment will be within 20%, but do not be concerned if the burn time goes up or down by as much as 50%.
Step 6: When doing halftones and process color separations, laser printers are limited in how fine a screen they can produce. A 12OOdpi laser printer can produce up to an 85 line screen. Beyond that, banding will occur in the image due to a reduction in the number of color/gray changes that can be physically represented. An 18OOdpi laser printer may be able to produce a finer screen - say 106 lines - but the limiting factor becomes the size of the toner particles. Try screens in a test before using them in production. Lower-resolution laser printers will produce correspondingly coarser screens.
