negative pre-sensitized offset printing plate
introduction
jinyan negative ps plates have high pressrun, proper exposure rate,simple plate making,
and perfect dot reproduction advantages and so on. in order to makethe plate reach its best
printing efficiency, please use it under the followingconditions.
1. printing down(exposure):
negative ps plate’ exposure is finished by negative film jointingnearly with sensitive plate,
spectrum range is between blue ray and ultraviolet ray (320-450nm),while exposing, the iodine
gallium lamp is the most proper lamp-house and around 150mj/c ㎡exposure is
recommended, in the actual operation, the exposure time can bedifferent according to different
exposure e and different film sort. so the exposure timemust be decided by actual
experiment result.
(1) put fuji gray scale (0.15 tier) on the edge of plate and underthe film, choose the
proper exposure to expose the plate, after finishingexposing, wash the plate,
the optimum exposure can be determined on the ninth stepwithout
printing ink.
(2) use ugra pcw82 control strip, choose proper exposure toexpose it, when
the 15-20um weenie line appear on the control strip, the exposure reach its
optimum state.
15~20μ
weenie line sketch map
(3) remark:
in order to reach the most pressrun, the exposure must beenough;
in order to prevent halftone (net dot) being scale-up, the exposure can’t be
added or decreased optionally. avoid the tone value, transferredfrom film with
halftone to printing plate, increasing excessively and decreasingexcessively so that
the thin part of the dark area disappearing; the tone value must becontrolled in the
permitted range.
(4) before using our plate to print, please operate it under theyellow safe light to
prevent exposing before printing for fear ituality.
2. develop
kodak -956 developer and our company’s negative developer arestrongly
recommended.
develop temperature: 25±2℃ developer’s dilution ratio:1:1(developer: water)
develop time: 30-60 seconds.
manual develop: must scrub, wash off remnant developer on thesurface of plate.
automatic develop: develop machine must be e with brush toreinforce
developing efficiency.
introduction:
(1) because the developer from different area is of diversity, someof negative plate will
appear shallow yellow on the surface after developing, with theplate substrate being
using, the shallow yellow will disappear automatically, it won’tinfluence printing
effect (kodak -956 developer has no such problem).
(2) in order to solve the problem, you can expose the developedplate once again, that
will not only eliminate the shallow yellow but also enhancepressrun.
3. correction:
in order to wipe off the excrescent image and stain, you can layright negative
remover on the surface of image or stain. 15 seconds later, washthe surface.
4. inking up (dip ink):
the function of dipping ink to negative plate is to enhance theimage area’s capability of
absorbing ink and enduring fretting. the negative plate must belaid a layer of sensitive
colophony additionally on the image area.
5. lay on gum.
the gum must be diluted under the manufacturer’s re, andthe layer should
be well-distributed. too thin or too thick all will influence theeffect, and if you lay on
gum automatically, please control the drying temperature.
6. storage
(1) before using: the negative plates should be stored in the cool(10—30℃), dark and
dry place. relative humidity ≤60%.
(2) storage life: six months.
