Term
| viscosity of fountain solution with IPA? |
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Definition
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Term
| viscosity of fountain solution with alcohol substitute? |
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Definition
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Term
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Definition
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Term
| dampening speed with alcohol substitute |
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Definition
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Term
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Definition
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Term
| surface tension of fountain solution requirement at high speed printing |
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Definition
| low surface tension is important for high printing speed! |
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Term
| what lowers surface tension? |
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Definition
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Term
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Definition
affects density and gloss
alcohol = diluent
alcohol substitute = not a diluent! |
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Term
| what is best and causes dot gain? |
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Definition
| small water droplets in ink |
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Term
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Definition
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Term
| how does overemulsification affect density, drying rate, ink tack ink viscosity? |
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Definition
density = down
drying rate = down
ink tack = down
ink viscosity = down |
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Term
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Definition
ink droplets in fountain solution
(droplets on the background) |
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Term
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Definition
from the mixture of air and water by the circulating pump
air bubble in fountain solution pops and lets ink go onto the non-image area! |
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Term
| durometer of metering roller in an alcohol system |
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Definition
want 20-30
higher #= harder ; lower # = softer |
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Term
| durometer of metering roller in alcohol-free system |
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Definition
want 18-23
higher #= harder ; lower # = softer |
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Term
| which durometer of metering roller is harder-- alcohol system or alcohol-free system? |
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Definition
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Term
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Definition
problem with using a harder metering roller in an alcohol-free system
lines on the chrome roller...around the cylinder |
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Term
| the nip strip between chrome roller and dampening roller...running IPA |
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Definition
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Term
| the nip strip between chrome roller and dampening roller...running alcohol substitute |
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Definition
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Term
| the speed of the metering roller...running IPA |
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Definition
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Term
| the speed of the metering roller running alcohol substitute |
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Definition
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Term
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Definition
| allowing more water to be fed at the ends of the system than in the middle |
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Term
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Definition
light and dark streaks around cylinder on the print
= streaking as printing direction |
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Term
| what kind of ink is desired |
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Definition
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Term
| Signs of good ink and water balance |
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Definition
-reach the specified density
-good trapping
-small dot gain
-good print contrast
-dry properly |
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Term
| excessive water (fountain solution) will penetrate onto roller surface, causing... |
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Definition
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Term
| what is the rule of thumb of ink/water balance? |
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Definition
| least amount of ink, least amount of water, least amount of problem! |
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Term
| each printing unit consists of... |
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Definition
-dampening system
-inking system
-plate cylinder
-blanket cylinder
-impression cylinder
-transfer drums |
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Term
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Definition
most widely used in sheetfed printing
drying time between units
impression cylinder = single or double-sized |
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Term
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Definition
more compact design
two blanket cylinders print onto a common impression cylinder
drying time of each color |
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Term
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Definition
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Term
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Definition
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Term
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Definition
a narrow groove
between bearer ring and cylinder body |
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Term
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Definition
| cylinder body is lower than bearer |
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Term
| pressure between plate and blanket cylinders |
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Definition
direct bearer contact
cannot change distance between blanket and plate (fixed by the gears)
pressure determined by packing (the thickness of plate, blanket and underlay) |
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Term
| pressure between blanket and impression cylinders? |
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Definition
can be adjusted
determined by the thickness of the substrate |
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Term
| problems caused by excessive packing? |
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Definition
distorted images
dot gain
slur
doubling
wear of plates and blankets |
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Term
| problems caused by inadequate packing? |
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Definition
uneven ink transferring
broken images |
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Term
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Definition
kraft paper- water resistant with different thickness
polyester- chemical resistant, not for packing blanket |
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Term
| setting up the ink rollers |
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Definition
| start at ductor roller and end with form rollers |
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Term
| heavy and uneven pressure settings cause... |
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Definition
ink distribution problems
increased roller wear
excess heat |
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Term
| the resistance method (setting up rollers) |
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Definition
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Term
| ink stripe method (setting up rollers) |
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Definition
use light ink (opaque white or yellow)
check the width and shape of stripe |
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Term
| what type of blanket is noncompressable? |
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Definition
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Term
| which blanket bugles out at the nip when squeezed? |
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Definition
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Term
| which blanket cannot be compressed but displaced? |
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Definition
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Term
| which blanket has better release properties for printing better solids? |
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Definition
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Term
| which blanket requires precise packing? |
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Definition
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Term
| which has a "hard" blanket? |
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Definition
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Term
| which blanket has a higher printing pressure? |
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Definition
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Term
| which is the old style blanket? |
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Definition
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Term
| which blanket has a higher resolution? |
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Definition
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Term
| which blanket has a spongy feeling? |
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Definition
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Term
| which blanket compresses in the printing nip? |
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Definition
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Term
| which blanket functions like a shock absorber? |
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Definition
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Term
| which blanket improves ink transfer? |
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Definition
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Term
| which blanket requires more packing squeeze, more packing latitude? |
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Definition
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Term
| which blanket is capable of printing dots and fine tones? |
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Definition
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Term
| which blanket reduces plate wear? |
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Definition
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Term
| which blanket has better smash resistance? |
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Definition
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Term
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Definition
same as color threads
stronger direction |
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Term
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Definition
opposite of warp direction
weaker direction |
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Term
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Definition
will affect print quality characteristics (dot sharpness, paper release)
special requirements for UV inks |
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Term
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Definition
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Term
| smooth blankets equal ____ dot |
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Definition
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Term
| higher release force can cause... |
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Definition
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Term
| blanket release-- what does a poor release cause? |
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Definition
dot distortion
excessive sheet curl or tail end hook! |
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Term
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Definition
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Term
| more or less curl: tackier ink |
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Definition
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Term
| more or less curl: slower printing speed |
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Definition
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Term
| more or less curl: thinner paper |
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Definition
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Term
| there is more curl in the... |
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Definition
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Term
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Definition
used on duplicator and some small presses
top sheet is separated and lifted at the FRONT
sheet travels the same as press
kind of slow!! |
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Term
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Definition
faster ... overlay of papers!
high-speed presses with large formats
top sheet is separated and lifted at the BACK edge
air nozzle blows air to make sheet flow into system |
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Term
| three-point sheetfed alignment system on feeding board |
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Definition
two front guides and one side guide (with pull roll)
only activate one side guide! |
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Term
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Definition
damages blanket (too thick of paper goes through)
mechanical...set the caliber of the paper |
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Term
| early and late sheet detectors |
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Definition
turn off the pressure between impression and blanket cylinders
misfeeding! ... causes ink to get on impression cylinder instead of missing sheet which = printing on front and BACK of next sheet |
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Term
| transferring sheet between units |
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Definition
chain transfer (cheaper)
drum transfer |
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Term
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Definition
single-revolution
double-sized (grabs 2 papers at a time)
triple-sized (grabs 3 papers at a time) |
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Term
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Definition
the right edge becomes the left edge, the front edge remains the same
switch the side guide to the opposite side
keeps the same gripper side! |
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Term
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Definition
the front edge becomes the rear edge, the side edges stay the same
must include two gripper margins
switches gripper! |
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Term
| pros and cons of spraying powder |
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Definition
Pros
-ink dries faster
-avoid smearing, offsetting and blocking of image
Cons
-soiling press
-reduce gloss
-finishing problems (dirty)
-powder on blankets: piling (ink doesn't transfer to paper as well now) |
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Term
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Definition
dots appear elongated or smeared on a single unit
only in printing direction! |
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Term
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Definition
1) blanket packing is not right-- overpacked
2)plate, blanket, paper/substrate = super smooth surface
3) print too much ink on coated paper
4)ink form rollers: too tight (high pressure) |
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Term
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Definition
| second image appears along side of first image |
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Term
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Definition
1) sheet slips at gripper
2) paper is not flat (wrinkled/wave edge, etc.) |
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Term
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Definition
| non-image areas show ink spots |
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Term
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Definition
1) ink/water balance...too much FS
2) ink droplets in FS |
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Term
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Definition
| ink film remains wet or tacky for a long time |
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Term
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Definition
1)substrate issue: coated vs. uncoated
2)ink film (too much ink = slower)
3)humidity / environment
4)fountain solution
5)metallic inks dry slower |
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Term
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Definition
ink transfer to the back side of the sheet
slow down the speed of the press |
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Term
| chemical or gloss ghosting |
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Definition
| a large solid on the back-up side of sheet shows excessive gloss |
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Term
causes of chemical/gloss ghosting
remedies |
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Definition
1) ink coverage on both sides are different
2) drying problem
(black blocks darker from red blocks on other side)
remedies: print heavy coverage first |
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Term
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Definition
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Term
causes of mechanical ghosting
remedies |
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Definition
1) ink starvation (# form rollers...4 is better than 3!)
2) layout
3) form roller
remedies: use more form rollers |
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Term
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Definition
contains a layer of silicone (=very low surface energy...non-image)
image area has higher surface energy
base = aluminum or polyester
(pic in notes!) |
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Term
| control temperature in waterless offset printing? |
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Definition
control with cooling system
too low temperature = CMT (critical mottle temperature)...very viscous-- "orange peel" appearance = uneven appearance
too high temperature = CTT (critical toning temperature)...less viscous
= tinting/toning |
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Term
print quality of conventional offset vs waterless offset
(solid ink density, dot gain, print contrast, substrates requirement) |
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Definition
conventional:
-dot gain=
-solid ink density=
-print contrast=
-substrate requirement=
waterless offset:
-higher density
-dot gain = slightly lower
-higher print contrast
-substrate requirement = paper with higher surface strength |
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Term
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Definition
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Term
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Definition
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Term
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Definition
Pro's
-most economical coating
-can apply flood or spot coating
-cab be applied on any unit
-cheaper!
-different gloss levels
Con's
-can yellow overtime |
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Term
| pros and cons of aqueous coating |
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Definition
Pro's
-eliminates spray powder
-dries faster
-excellent rub resistance
-non-yellowing
-glueable, foil stampable
Con's
?? |
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Term
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Definition
located after the last print unit
has anilox roll and blanket
can use to varnish |
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Term
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Definition
aqueous coating is used as UV primer before a UV coating
allow the job to sit for 24-48 hours |
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Term
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Definition
problem pigments
pH
ink contains die |
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Term
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Definition
use Zahn cup to measure viscosity
check viscosity every few hours
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Term
| variables affecting viscosity |
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Definition
-temperature (too cold/warm)
-fast drying coatings will have a tendency to lose water during production run |
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Term
| print over aqueous coating by inkjet |
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Definition
water-based: leaves a window (where address is printed on a magazine)
alcohol-based (solvent based): print over aqueous coating...whole sheet (not just window) |
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Term
| pressure settings on aqueous coater |
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Definition
"kiss" method-- just enough pressure
(very small impression...not pressed hard) |
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Term
| requirements for coating on both sides |
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Definition
special formulation: work and turn formula (can stand a higher temperature)
apply least amount of coating as possible |
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Term
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Definition
-alligatoring or mudcracking of coating
-backtrapping
-pinhole and orange peel appearance
-color shift: color changes caused by dyes or trouble colors
-sheet curl: thin paper curls more from excessive heat |
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Term
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Definition
low weight paper
excessive heat |
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Term
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Definition
-ink gets on coating blanket...happens from:
-too much pressure
-coating does not wet ink properly
-ink is pulled from sheet
-ink is overemulsified
-too little coating |
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Term
| pinhole and orange peel appearance |
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Definition
= waxy
-coating does not wet the ink
-coating is foaming |
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Term
| materials used in testing a press |
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Definition
-plates: determine resolution
-blankets: quick release for sharp dots
-paper: #80 or #100
-inks: make sure they have acceptable dot gain and overprint trap has reasonably ink film thickness
-fountain solution: make sure it is compatible with inks and plates
-want to control the pH conductivity |
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Term
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Definition
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Term
| what kind of blankets are used for sharp dots? |
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Definition
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Term
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Definition
#80 or #100 C2S gloss
grade #1 or #2 |
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Term
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Definition
| acceptable dot gain and overprint traps at reasonable ink film thickness |
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Term
| fountain solution is compatible with ____ and ____ and controls _____ and _____ |
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Definition
compatible with ink and plates
controlled pH and conductivity |
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Term
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Definition
run on each unit to check impression
no fountain solution
ink takes over plate |
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Term
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Definition
run on each unit to check dampening solution
need to burn plate with no exposure
fountain solution is everywhere = no ink!! |
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Term
| How do you determine if the ink density is consistent? |
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Definition
| by pulling 50 consecutive and 50 random sheets |
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Term
| neutral color defined by GRACoL 7? |
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Definition
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Term
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Definition
combined oil-based and UV inks
dries fast!
uses regular rollers/blankets...dries by radiation |
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Term
| what type of paper has a harder time releasing? |
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Definition
| smooth blanket release is harder than rough |
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Term
| where do you store a blanket? |
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Definition
in a dark, dry and cool plate
store in tubes
store flat
rubber face rubber
fabric face fabric |
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Term
| what should you avoid when handling blankets? |
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Definition
| avoid prolonged exposure to light |
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Term
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Definition
make a calibration run using a linear CTP plate
the information in a digital file that tells you what % to burn on the plate |
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Term
| wrinkled or doubled sheet wont damage what kind of blanket? |
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Definition
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Term
| color shift in acqueous coating and UV coating |
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Definition
trouble colors = rhodamin red, reflux blue, violet, purple
...causes color shifting |
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Term
| substrate requirements of aqueous coating and UV coating |
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Definition
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Term
| coating quality differences (acqueous coating, varnish and UV coating) |
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Definition
UV = highest quality
aqueous = middle quality
varnish = lowest quality |
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Term
| more or less curl: runny ink |
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Definition
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Term
| more or less curl: higher printing speed |
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Definition
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Term
| more or less curl: thicker paper |
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Definition
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