Odisha CHSE +2 Vocational Printing Technology common mistakes
Odisha CHSE +2 Vocational Printing Technology · Understand the traps and how to avoid them.
Calculating the number of sheets or plates needed for a job by multiplying the number of pages by the number of copies, instead of working from the number of pages divided by pages-per-sheet and then adding make-ready and spoilage allowances.
Candidates memorise the formula for sheet count in isolation and never link it to the imposition scheme, so they treat 'pages' and 'sheets' as interchangeable and forget that a 16-page signature puts 16 pages on two sides of one sheet.
What to do instead
Before any calculation, write the imposition down explicitly: pages per side, pages per sheet, then sheets = total pages ÷ pages per sheet. Practise with 8, 16 and 32-page signatures, then add a stated overs allowance (typically 2–5% for make-ready) as a separate line. Always state units (pages, sheets, impressions) next to every number.
Confusing screen ruling, screen angle and dot shape, or describing halftone dots as 'frequency of dots per centimetre of the image' rather than lines per centimetre/inch of the screen.
The three variables are taught together and all describe the halftone screen, so candidates blur the definitions and cannot state why yellow is normally set at 90° or why 30°/60° separation prevents moiré.
What to do instead
Build a one-line definition card for each: ruling = lines per cm (resolution of the screen), angle = rotation of the dot grid, shape = geometry of the dot (round, elliptical, square, FM). Then learn the standard angle set (black 45°, magenta 75°, cyan 15°, yellow 90°) with the reason attached: maximum separation between the three strongest colours reduces moiré.
Treating trapping, overprint and knockout as synonyms when describing colour separation and prepress setup.
All three concern how adjacent or overlapping colours are handled at the press, and candidates learn them as a list of prepress 'settings' without the underlying reason - registration tolerance and ink adhesion.
What to do instead
Anchor each term to a physical consequence: knockout removes the underlying colour (risk of white gaps on misregistration), overprint prints one ink on top of another (used for black text and for avoiding gaps), trapping is a deliberate slight overlap (spread or choke) sized to the press's registration tolerance. State the tolerance in mm for a given press type when you use the term.
Classifying a printing process only by the plate material, for example calling all 'offset' work 'lithography on metal plates', and then failing to distinguish sheetfed offset, web offset, flexography, gravure, screen and digital inkjet when asked to select a process for a job.
Syllabus lists of processes are memorised as names with one attribute each, so candidates cannot match a process to a job requirement such as long-run packaging, short-run variable data, or printing on corrugated board.
What to do instead
For each process, learn a five-point profile: image carrier, ink type, typical substrate, economic run length, and one characteristic strength and weakness. Then practise 10 short 'choose the process and justify' scenarios (e.g. 200,000 cartons, 500 personalised invitations, shrink sleeves) and write the justification in one sentence using the profile.
Describing the offset printing unit without the correct sequence of cylinders and rollers, or omitting the dampening system and the ink–water balance when explaining print quality problems.
Candidates learn the press as a labelled diagram and reproduce labels in the wrong order, and they treat dampening as a separate topic rather than the cause of many scumming, tinting and emulsification faults.
What to do instead
Draw the plate–blanket–impression cylinder stack from memory three times and label the inking train and dampening train on the same drawing. Then write a fault table linking ink–water imbalance to specific symptoms: scumming (too little water), tinting/emulsification (too much water), poor ink transfer and dot gain.
Giving paper properties as a list of names (grammage, bulk, opacity, smoothness) without units or without linking a property to a printing consequence.
Paper is studied as definitions to be recalled, and candidates do not practise converting gsm to ream weight or explaining why a 70 gsm maplitho behaves differently from a 300 gsm board on the same press.
What to do instead
For every property, record the unit and one consequence: grammage (g/m²) sets stiffness and calliper; bulk (cm³/g) sets thickness at a given grammage; smoothness affects dot reproduction and ink demand; opacity affects show-through; pick resistance governs whether the surface lifts on a tacky ink. Practise ream-weight arithmetic: ream weight = area of one sheet × gsm × 500.
Explaining ink drying by naming only 'oxidation' or only 'absorption', and not matching drying mechanism to ink type and substrate.
Drying is taught as a short list of mechanisms and candidates pick the one they remember, missing that offset inks on coated stock rely mainly on oxidation and setting, while news inks rely on absorption into uncoated stock, and UV inks cure by radiation.
What to do instead
Build a matrix of ink type against substrate and drying mechanism, then test yourself with 'why does this job set off in the delivery pile?' style questions. Include the practical controls: anti-set-off spray, pile height, ink film thickness, and the role of driers in oxidation.
Mixing up the binding and finishing operations - calling perfect binding a 'stitched' book, confusing saddle stitching with side stitching, or describing lamination as a folding operation.
The operations are learned as a vocabulary list in one chapter, and candidates never sequence them, so they cannot say what happens before and after what in a real job.
What to do instead
Write the production sequence for three products from printed sheet to finished item: a 16-page saddle-stitched booklet, a 200-page perfect-bound book, and a folded leaflet. For each, name imposition, folding, collation, binding, trimming and any surface finishing in order, and state the grain direction requirement (spine parallel to grain for perfect binding).
Answering maintenance and safety questions with generic statements such as 'keep the machine clean' or 'follow safety rules', instead of naming the specific check, interval or hazard control.
Safety and maintenance are often revised last and treated as common sense, so candidates do not learn the scheduled items (roller settings, blanket and plate cylinder condition, lubricant type, guard interlocks) or the specific hazards (nip points, solvent vapour, UV radiation, noise).
What to do instead
Make a preventive maintenance table with item, frequency and reason (e.g. check roller pressures daily to avoid uneven ink transfer; clean dampening rollers weekly to prevent glaze and tinting). For safety, learn the hierarchy - guard, interlock, PPE, procedure - and name the specific hazard each control addresses.
Costing a print job by adding a flat percentage 'profit' to material cost only, ignoring make-ready waste, machine hour rate, labour, plates and finishing, and then misreading a density or dot-gain reading in quality-control questions.
Costing and colour measurement are the two quantitative areas candidates avoid, so they substitute rules of thumb; in colour questions they confuse density (ink film) with dot gain (tone value increase) or read a densitometer value against the wrong solid.
What to do instead
Cost a small job line by line: paper (with spoilage), ink, plates, machine hours at a stated rate, labour, finishing, overhead, then margin - and check the selling price against a per-copy sanity check. For colour, define density, dot gain, and trap separately, then practise reading a control strip: solid density against the target, 50% tint for dot gain, and overprints for trap.