Study Guides (248,012)
Canada (121,226)
GRA 324 (5)
Ian (1)
Quiz

LAB TESTS.pdf

3 Pages
157 Views
Unlock Document

Department
Graphic Communications
Course
GRA 324
Professor
Ian
Semester
Fall

Description
LAB TESTS 1. TEMPURATURE/RELATIVE HUMIDITY (RH) OF PAPER Degrees Celsius Relative Humidity %  increases  positive  decrease  negative Paper is hydroscopic  absorbs and releases moisture Wavy Edges Tight Edges Hydrometer  make/model # RH Level  35-50% = good pressroom conditions Ink dries – it absorbs and oxidizes creating film Build up of Static Electricity when moisture is in the air, there is no static charge  sheets of paper don’t separate properly 2. FOLDING ENDURANCE TEST Determine grain direction  5 long, 5 short, then discuss the average and range 4. INK DRYING TIME Use Sheetfed Offset Inks Pigment  colours Varnish cavius pigment, sets drying properties Vehicle: Resin Oils Dryers vegetable (metal solvants) mineral oils cobalt drying oils manganese metal soybean oil Dries in 2 Stages 1) ABSORPTION  “setting” Uncoated varnish is absorbed into paper, while pigment sits on top Coated varnish sits on top of paper , white pigment is on top of coat Set-Off  discuss in report, usually a powder to drink ink, leaves scuff marks of ink btw/ sheets 2) OXIDATIVE POLYMERIZATION  exposed to oxygen Uncoated  absorbs faster Coated polymerizes faster, more varnish exposed to oxygen  solidifying of ink (the ink thickens and dries)  hydroperoxide (oils + oxygen)  hydroperoxide + driers = polymerization (chemical reaction to start drying itself) Discuss for Report:  Use Black/Cyan/Magenta colours for lab test  Porosity of paper  Viscosity of ink  Humidity/temp of press room  pH level of paper or fountain solution 5. INK MIXING Write down pantone # Mixing Inks use scales, 50g/2 or 25%, Quickpeek Kit print on coated and uncoated 7. BASIS WEIGHT TEST Calculate: Lumiart Gloss Text 17.5x23 59M  Does this paper weight what the label says it weighs? 1. Nominal Basis Weight 2. Actual Basis Weight M Wt  Basis Wt = Area Basic Size x M Wt
More Less

Related notes for GRA 324

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit