I85PREP
⌘ K
ITI/NCVT Painter General (AITT Theory) study materials
ITI/NCVT Painter General (AITT Theory) study resources

ITI/NCVT Painter General (AITT Theory) practice questions

One question at a time. Build your ITI/NCVT Painter General (AITT Theory) understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Safety, Health, Environment and First Aid

In a painting shop, which type of fire extinguisher is the correct first choice for a fire involving solvents, thinners and paint in open containers?

  1. Water (Class A)
  2. Foam (Class B)
  3. Carbon dioxide (Class B/C) Correct answer.
  4. Dry sand only

Explanation

Flammable liquids such as thinner and solvent-based paint are Class B fires. Carbon dioxide extinguishes them by smothering and cooling without leaving residue and is safe near electrical equipment. Water spreads the burning liquid, and plain sand smothers but is not a standard extinguisher media for a spray shop.

Question 2Safety, Health, Environment and First Aid

A painter feels dizzy and nauseous while spraying solvent-based paint in a small room with the door closed. What is the correct immediate action?

  1. Move the person into fresh air and call for help Correct answer.
  2. Open the window and let the person keep spraying
  3. Lay the person flat inside the spray booth
  4. Give the person strong coffee and continue work

Explanation

Dizziness and nausea in a confined spray area indicate solvent vapour inhalation. The casualty must be removed to fresh air immediately and medical help summoned. Leaving them in the contaminated area, even with a window open, delays recovery and risks unconsciousness.

Question 3Safety, Health, Environment and First Aid

What does the 'H' in the COSHH risk assessment used in painting work stand for?

  1. Hygiene
  2. Hazard Correct answer.
  3. Hearing
  4. Handling

Explanation

COSHH stands for Control of Substances Hazardous to Health. The assessment first identifies the hazard of each substance, such as toxicity or flammability, and then evaluates the risk of exposure in the actual task. Handling, hygiene and hearing are separate safety topics, not part of the COSHH acronym.

Question 4Safety, Health, Environment and First Aid

Which personal protective equipment is essential when mixing two-pack epoxy paint containing isocyanate hardener?

  1. Ear plugs and safety boots only
  2. Cotton overalls and open sandals
  3. Air-fed or suitable respiratory protection plus gloves and eye protection Correct answer.
  4. A dust mask and a cloth cap

Explanation

Isocyanate hardeners can cause serious respiratory sensitisation, so mixing requires effective respiratory protection, usually air-fed or an approved cartridge mask, together with gloves and eye protection for splashes. Ordinary dust masks do not stop isocyanate vapour. Footwear and hearing protection do not protect the lungs or skin.

Question 5Safety, Health, Environment and First Aid

Why must paint containers and solvent rags be placed in a closed metal bin with a lid at the end of a shift?

  1. To stop them being stolen
  2. To prevent vapour build-up and spontaneous ignition Correct answer.
  3. To make the workshop look tidy
  4. To keep the paint from drying out

Explanation

Solvent-soaked rags can heat up through slow oxidation and ignite spontaneously, and open containers release flammable vapour that can reach an ignition source. A closed metal bin with a lid limits both vapour release and the air supply that supports self-heating. Tidiness and theft prevention are not the safety reason.

Question 6Safety, Health, Environment and First Aid

A painter must work on a ladder to reach a ceiling edge. Which practice keeps the task within safe limits?

  1. Ask a colleague to hold the ladder while standing on the top rung
  2. Stand on the top two rungs for extra height
  3. Lean far to one side to reach the corner
  4. Keep the body centred between the stiles and move the ladder as needed Correct answer.

Explanation

Ladder work is safe only when the body stays centred between the stiles and the ladder is repositioned rather than overreached. Standing on the top rungs or leaning out shifts the centre of gravity and causes falls. A colleague steadying the ladder does not make the top rung a safe standing place.

Question 7Safety, Health, Environment and First Aid

A spray gun must be cleaned with thinner. Which method best controls both fire and health risk?

  1. Rinse it in the hand-wash sink
  2. Clean it in an open bucket beside the spray booth
  3. Use a closed gun-washer with extraction and grounded metal parts Correct answer.
  4. Blow it dry with compressed air into the workshop

Explanation

A closed gun-washer with local extraction contains solvent vapour and keeps solvent away from ignition sources, while grounding prevents static sparks. Open cleaning, compressed-air blowing and sink rinsing all release vapour into the workroom. Grounding is essential because static discharge can ignite solvent vapour.

Question 8Safety, Health, Environment and First Aid

What is the main purpose of bonding and grounding a metal paint container during decanting?

  1. To stop the paint from settling
  2. To speed up the pouring of thick paint
  3. To keep the container cool in summer
  4. To prevent static sparks that could ignite vapour Correct answer.

Explanation

Pouring solvent-based paint generates static electricity, and an ungrounded container can discharge a spark into the flammable vapour above the liquid. Bonding the two containers and grounding them equalises potential and removes the spark risk. Settling, pouring speed and temperature control are unrelated to this measure.

Question 9Safety, Health, Environment and First Aid

A worker splashes thinner into the eye. What is the correct first-aid sequence?

  1. Apply eye drops and cover the eye with a rag
  2. Rub the eye and continue working
  3. Wait until the end of the shift to report it
  4. Flush with clean water for at least 15 minutes and seek medical help Correct answer.

Explanation

Chemical eye splashes must be irrigated immediately with clean, low-pressure water for at least 15 minutes while the eyelids are held open, then the casualty is taken for medical assessment. Rubbing or delaying irrigation allows the solvent to damage the cornea. Eye drops and rags are not sterile irrigation and do not remove the chemical.

Question 10Safety, Health, Environment and First Aid

In a manual-handling assessment for lifting a 25 kg drum of paint, which control comes first in the hierarchy of control?

  1. Issue back-support belts
  2. Rotate the lifting task among workers
  3. Train the painter in lifting technique
  4. Provide a drum trolley or mechanical aid Correct answer.

Explanation

The hierarchy of control for manual handling starts with eliminating or mechanising the lift, so a trolley or other mechanical aid is the preferred first control. Training, belts and job rotation are administrative or personal measures that come after engineering controls. They reduce risk only after the load itself has been addressed.

Question 11Safety, Health, Environment and First Aid

Which sign colour and shape indicates a mandatory instruction such as 'Wear eye protection' in a paint store?

  1. Green square with a white symbol
  2. Red circle with a diagonal bar
  3. Yellow triangle with a black border
  4. Blue circle with a white symbol Correct answer.

Explanation

Mandatory signs are blue circles with a white pictogram, telling people what they must do. Red circles with a bar prohibit, yellow triangles warn, and green squares indicate safe conditions or escape routes. Recognising these shapes lets a painter read a workplace at a glance.

Question 12Safety, Health, Environment and First Aid

A spray booth extraction fan fails during a solvent-based spraying job. What should the painter do first?

  1. Increase the spray gun pressure to compensate
  2. Continue spraying and finish the panel quickly
  3. Stop spraying, switch off ignition sources and ventilate the area Correct answer.
  4. Close the booth doors and keep working

Explanation

Without extraction, solvent vapour builds up rapidly towards its lower explosive limit and harms the painter's health. Work must stop, potential ignition sources isolated, and the area ventilated before any restart. Finishing quickly, raising pressure or sealing the booth all increase the vapour concentration.

Question 13Safety, Health, Environment and First Aid

Which statement correctly describes the difference between a hazard and a risk in painting work?

  1. A hazard is the chance of harm and risk is the substance itself
  2. A hazard is the potential to cause harm and risk is the likelihood and severity of that harm Correct answer.
  3. Hazard and risk mean exactly the same thing
  4. Risk applies only to fire and hazard only to health

Explanation

A hazard is anything with the potential to cause harm, such as a toxic solvent or a flammable vapour. Risk is the combination of how likely that harm is and how severe it would be in the actual task. The two words are therefore not interchangeable, and both fire and health hazards carry risk.

Question 14Safety, Health, Environment and First Aid

During spray painting near a solvent store, a colleague collapses and is not breathing normally. A defibrillator is available. What is the correct sequence?

  1. Sit the person upright and give water
  2. Give two rescue breaths only and wait
  3. Call emergency services, start chest compressions and apply the defibrillator as soon as possible Correct answer.
  4. Move the person outside and leave them to recover

Explanation

For an unresponsive casualty who is not breathing normally, the priority is to summon emergency help, begin high-quality chest compressions and attach an automated external defibrillator as early as possible. The defibrillator analyses the rhythm and shocks only if needed, so it is safe to use. Waiting, giving water or leaving the casualty alone loses critical minutes.

Question 15Safety, Health, Environment and First Aid

A workshop stores 20 litres of solvent-based paint and 20 litres of thinner in a small room shared with a gas-fired heater. Which arrangement best meets fire safety principles?

  1. Keep the containers in the heated room and rely on a smoke detector
  2. Move the containers next to the exit door for quick removal
  3. Store them in a fire-resisting cabinet away from the heater, with ventilation and spill containment Correct answer.
  4. Stack the containers on a wooden shelf above the heater

Explanation

Flammable liquids must be kept in a fire-resisting, ventilated store away from ignition sources such as a gas heater, with spill containment to control leaks. A smoke detector alone does not prevent ignition, and placing containers near an exit or above a heater increases the danger. Segregation from ignition sources is the key principle.

Question 16Safety, Health, Environment and First Aid

A painter develops red, cracked and itchy skin on the hands after weeks of handling solvent-based paints without gloves. Which condition and control is most appropriate?

  1. Occupational contact dermatitis; use suitable gloves, wash with mild cleanser and report to the supervisor Correct answer.
  2. A minor graze; cover it with tape and keep working
  3. Frostbite; warm the hands and continue without gloves
  4. Normal wear; no action is required

Explanation

Repeated skin contact with solvents and resins removes natural oils and can cause occupational contact dermatitis, which is reportable and can become chronic. The control is to wear gloves suited to the chemical, wash with mild cleanser rather than solvent, and report the symptoms early. Continuing without protection allows the condition to worsen.

Question 17Trade Hand Tools, Measuring Instruments and Workshop Practice

In a painter's workshop, which hand tool is specifically designed for spreading putty over dents and scratches on a prepared surface?

  1. Hacksaw
  2. Putty knife Correct answer.
  3. Chisel
  4. Spirit level

Explanation

A putty knife has a flexible flat blade with a straight edge, which lets the painter press filler into a dent and level it flush with the surrounding surface. The tool is used with a slight scraping angle so the filler is compacted and not pulled out. Other tools listed serve cutting, metal cutting, or levelling purposes.

Question 18Trade Hand Tools, Measuring Instruments and Workshop Practice

A painter needs to check whether a newly plastered wall is truly vertical before priming. Which instrument is the correct choice?

  1. Vernier caliper
  2. Micrometer
  3. Plumb bob Correct answer.
  4. Try square

Explanation

A plumb bob hangs on a cord and establishes a true vertical reference by gravity, so it can be held against or near the wall to compare the wall face with the vertical line. A try square is for checking right angles on small work, while calipers and micrometers measure small thicknesses. Verticality of a large wall surface is therefore checked with a plumb line.

Question 19Trade Hand Tools, Measuring Instruments and Workshop Practice

What is the standard purpose of the cross-cut teeth pattern on a hand saw used in a painter's workshop?

  1. Cutting glass panes
  2. Cutting wood across the grain Correct answer.
  3. Cutting metal sheet
  4. Cutting threads in a hole

Explanation

Cross-cut saw teeth are sharpened with knife-like points and bevels that sever wood fibres across the grain, producing a clean end on a board. Ripping teeth are shaped differently for cutting along the grain. Metal, glass and threads each require their own dedicated tools.

Question 20Trade Hand Tools, Measuring Instruments and Workshop Practice

Which measuring tool would a painter use to set out a right angle at a corner of a door frame before fitting a panel?

  1. Steel rule
  2. Outside caliper
  3. Depth gauge
  4. Try square Correct answer.

Explanation

A try square has a stock and a blade fixed at exactly 90 degrees, so it is placed against one face to check or mark a perpendicular line on the other. The steel rule only measures length, calipers measure round and irregular thicknesses, and a depth gauge measures hole depth. Setting out a right angle therefore requires the try square.

Question 21Trade Hand Tools, Measuring Instruments and Workshop Practice

What is the correct purpose of a scraper in surface preparation before painting?

  1. Removing loose paint and high spots from a surface Correct answer.
  2. Polishing the final gloss coat
  3. Mixing two-pack paint with hardener
  4. Measuring the wet film thickness

Explanation

A scraper has a hardened, slightly burred edge that is pushed or pulled at a shallow angle to lift loose, flaking paint and shave off high spots. This produces a sound, level substrate for the next coat. Mixing, thickness measurement and final polishing are done with other tools.

Question 22Trade Hand Tools, Measuring Instruments and Workshop Practice

Which of the following is the correct way to store a steel rule in the workshop to preserve its accuracy?

  1. Hung or laid flat in a rack, away from moisture Correct answer.
  2. Wrapped in an oily rag inside a tool bag
  3. Kept clamped in a bench vice
  4. Lying loose in a box with files and chisels

Explanation

A steel rule keeps its graduations and straightness only if it is protected from knocks, bending and rust. Hanging it in a rack or laying it flat keeps it straight, and keeping it dry prevents corrosion of the marked face. Loose storage with heavier tools risks burring the edges and rubbing off the markings.

Question 23Trade Hand Tools, Measuring Instruments and Workshop Practice

A painter measures a wall as 4.20 m long and 2.75 m high. What is the area to be painted, to two decimal places?

  1. 13.90 m²
  2. 12.25 m²
  3. 10.50 m²
  4. 11.55 m² Correct answer.

Explanation

Area of a rectangle is length multiplied by height, so 4.20 m × 2.75 m = 11.55 m². This figure is then used to estimate paint quantity from the spreading rate. Adding the dimensions or halving them gives no meaningful area.

Question 24Trade Hand Tools, Measuring Instruments and Workshop Practice

How is the least count of a vernier caliper with 50 vernier divisions determined when the main scale division is 1 mm?

  1. 1 mm multiplied by 50, giving 50 mm
  2. 1 mm divided by 25, giving 0.04 mm
  3. 1 mm divided by 50, giving 0.02 mm Correct answer.
  4. 50 mm divided by 1 mm, giving 50

Explanation

Least count equals the value of one main scale division divided by the number of vernier divisions. With 1 mm main divisions and 50 vernier divisions, 1 ÷ 50 = 0.02 mm. This is the smallest reading the instrument can resolve.

Question 25Trade Hand Tools, Measuring Instruments and Workshop Practice

A surface is to receive two coats of emulsion with a spreading rate of 10 m² per litre per coat. The area is 45 m². How much paint is needed for both coats, ignoring waste?

  1. 4.5 litres
  2. 2.25 litres
  3. 18 litres
  4. 9 litres Correct answer.

Explanation

Each coat needs 45 ÷ 10 = 4.5 litres. Two coats therefore need 4.5 × 2 = 9 litres. Waste and absorption allowances would be added on top of this theoretical figure.

Question 26Trade Hand Tools, Measuring Instruments and Workshop Practice

Why is a folding wooden rule preferred over a steel tape for some internal measurements in finishing work?

  1. It is unaffected by moisture and will never warp
  2. It can be folded and read without assistance inside a recess Correct answer.
  3. It has a built-in bubble for checking level
  4. It measures to a finer least count than a micrometer

Explanation

A folding rule is rigid when extended and can be set into a recess and read directly by one person, which is awkward with a flexible tape that needs a second hand or a hook. It is a workshop measuring tool, not a precision instrument. Wooden rules do swell with moisture and carry no level vial.

Question 27Trade Hand Tools, Measuring Instruments and Workshop Practice

Which abrasive grade sequence correctly represents progressing from coarser to finer paper for smoothing a filled surface?

  1. P80, P120, P60
  2. P120, P60, P80
  3. P60, P80, P120 Correct answer.
  4. P120, P80, P60

Explanation

Abrasive grit numbers indicate particles per unit area, so a lower number is coarser. Working from P60 to P80 to P120 removes the bulk of the filler first and then refines the scratch pattern. Reversing the order leaves deep scratches that show through the finish.

Question 28Trade Hand Tools, Measuring Instruments and Workshop Practice

What is the main reason for using a straight edge together with a feeler gauge on a painted panel?

  1. To measure the gloss level of the finish
  2. To detect depressions and high spots in the surface Correct answer.
  3. To check the colour match under daylight
  4. To measure the hardness of the dried film

Explanation

The straight edge is laid across the panel and a feeler gauge is tried at the gap; the blade thickness that just enters shows how far the surface deviates from flat. This reveals hollows and ridges that would show as shadows in a gloss coat. Gloss, colour and hardness are assessed by other means.

Question 29Trade Hand Tools, Measuring Instruments and Workshop Practice

A hacksaw blade is fitted with the teeth pointing forward, away from the handle. What is the effect on normal cutting?

  1. The cut will be wider but smoother
  2. The saw will not cut efficiently because the teeth are oriented for the wrong stroke direction Correct answer.
  3. The blade will last longer because the set is reversed
  4. The saw cuts faster because the teeth rake the metal

Explanation

A hacksaw cuts on the forward push stroke, so the teeth must point away from the handle for the raker and set teeth to bite correctly. Fitting the blade the other way round makes it chatter and rub rather than cut. Blade life and kerf width are not improved by reversing the teeth.

Question 30Trade Hand Tools, Measuring Instruments and Workshop Practice

Why must a wooden measuring rule never be used as a lever or scraper on site?

  1. It will become magnetised and attract steel filings
  2. It may lose its straightness and the graduations may become inaccurate Correct answer.
  3. It will change colour and be hard to read
  4. It will conduct electricity dangerously

Explanation

A rule is a reference for length, and any bending or wear at its ends destroys that reference. Using it as a lever or scraper bends the stock and wears the end faces, so all subsequent measurements drift. Rules are not magnetised by such use and are poor conductors.

Question 31Trade Hand Tools, Measuring Instruments and Workshop Practice

A paint film is specified at 40 micrometres dry film thickness and the paint has 50 percent volume solids. What wet film thickness should be applied?

  1. 100 micrometres
  2. 40 micrometres
  3. 80 micrometres Correct answer.
  4. 20 micrometres

Explanation

Wet film thickness equals dry film thickness divided by the volume solids fraction, so 40 ÷ 0.50 = 80 micrometres. The solvent evaporates and leaves half the wet thickness as dry film. Applying the dry figure wet would give only 20 micrometres dry.

Question 32Trade Hand Tools, Measuring Instruments and Workshop Practice

A steel tape reads 3.2 cm on a 30 m survey when the tape temperature is 15 °C above its calibration temperature of 20 °C. Which correction applies and why?

  1. No correction is needed because steel does not change length with temperature
  2. The tape has expanded, so the recorded length is slightly short of the true length Correct answer.
  3. The tape has contracted, so the recorded length is longer than true
  4. The tape has stretched permanently and must be discarded

Explanation

Steel has a positive coefficient of linear expansion, so a warmer tape is longer than its calibrated length. Each tape unit then represents slightly more than a true unit, and a reading taken on it understates the true distance. The effect is small but cumulative over long measurements.

Question 33Trade Hand Tools, Measuring Instruments and Workshop Practice

A rectangular ceiling measures 5.5 m by 4.0 m and receives three coats at 8 m² per litre per coat. What is the theoretical paint requirement?

  1. 16.5 litres
  2. 8.25 litres Correct answer.
  3. 5.50 litres
  4. 2.75 litres

Explanation

Ceiling area is 5.5 × 4.0 = 22 m². One coat needs 22 ÷ 8 = 2.75 litres, and three coats need 2.75 × 3 = 8.25 litres. This theoretical quantity excludes losses to roller and brush.

Question 34Trade Hand Tools, Measuring Instruments and Workshop Practice

A painter must confirm that a large wall is both flat and vertical before applying a high-gloss finish. Which combination of workshop tools gives both checks?

  1. Plumb bob for verticality and a long straight edge for flatness Correct answer.
  2. Try square for verticality and a steel rule for flatness
  3. Spirit level vial for flatness and a hacksaw for verticality
  4. Vernier caliper for verticality and a depth gauge for flatness

Explanation

Verticality over a tall wall is best judged with a plumb line, while flatness along the face is checked by laying a long straight edge against it and looking for gaps or rocking. Each tool supplies the reference the other cannot. A try square and caliper are too small for wall-scale work.

Question 35Trade Hand Tools, Measuring Instruments and Workshop Practice

A surface is 18 m² and requires a primer at 6 m² per litre, followed by two finish coats at 9 m² per litre each. Allowing 10 percent extra for waste on the total, what is the nearest whole-litre order?

  1. 8 litres Correct answer.
  2. 10 litres
  3. 7 litres
  4. 9 litres

Explanation

Primer needs 18 ÷ 6 = 3 litres and the two finish coats need 18 ÷ 9 × 2 = 4 litres, giving 7 litres theoretical. Adding 10 percent waste gives 7.7 litres, which rounds up to 8 litres for ordering. Ordering exactly 7 litres would leave no allowance for loss.

Question 36Trade Hand Tools, Measuring Instruments and Workshop Practice

A wooden straight edge shows a gap of 2 mm at its centre when laid on a known flat surface plate. What does this indicate and what is the correct action?

  1. The surface plate is hollow and the straight edge is correct
  2. The gap is due to paint film and can be ignored
  3. The straight edge is bowed and must be re-trued or replaced before use Correct answer.
  4. The straight edge is too short and must be lengthened

Explanation

When a straight edge is checked against a reference flat such as a surface plate, any light gap shows that the edge itself is not straight. A 2 mm gap at the centre means the tool is bowed and will transfer that error to every surface it checks. It must be re-trued or replaced before further use.

Question 37Surfaces, Substrates and Surface Preparation

Before applying a primer to a new galvanised steel sheet, the painter should treat the surface to remove the zinc-based layer that prevents adhesion. Which preparation method is normally recommended for this purpose?

  1. Sanding with fine abrasive paper only
  2. Applying a mordant or etch primer solution Correct answer.
  3. Wiping with kerosene
  4. Washing with water and detergent

Explanation

Galvanised surfaces are covered with a passive zinc layer that ordinary sanding does not convert, so paint adheres poorly. An etch or mordant solution reacts with the zinc to create a keyed surface suitable for subsequent coats. Water washing only removes dirt, and kerosene leaves an oily film.

Question 38Surfaces, Substrates and Surface Preparation

Which surface preparation defect is indicated when a painted steel panel shows rust blisters that lift the coating from underneath?

  1. Insufficient dry film thickness
  2. Excessive thinning of the topcoat
  3. Trapped moisture or salt under the coating Correct answer.
  4. Over-application of the primer

Explanation

Rust blistering that pushes the film away from the steel starts at the interface, where moisture or soluble salts remain after cleaning. The corrosion products occupy more volume than the steel and lift the coating. Thin or thick films alone do not create this blister pattern unless contamination is present.

Question 39Surfaces, Substrates and Surface Preparation

What is the main purpose of abrasive blasting a steel surface before painting?

  1. To apply a thin zinc coating
  2. To reduce the steel thickness for economy
  3. To increase the surface area and remove mill scale and rust Correct answer.
  4. To polish the steel to a mirror finish

Explanation

Blasting removes mill scale, rust, and old coatings while creating an anchor profile that improves mechanical adhesion. The roughened profile gives the primer a key. Polishing, galvanising, and thinning are not objectives of blasting.

Question 40Surfaces, Substrates and Surface Preparation

A painter is preparing a concrete wall that has a glossy, dense surface. Which treatment gives the best key for the subsequent coating?

  1. Etching with a dilute acid solution followed by rinsing Correct answer.
  2. Brushing on a thick coat of oil paint
  3. Applying a sealer without any preparation
  4. Wiping with a dry cloth

Explanation

Dense, glossy concrete has a closed surface that coatings cannot penetrate. Acid etching opens the surface and removes laitance, and thorough rinsing removes reaction salts. Dry wiping and sealing over an unprepared surface give poor adhesion.

Question 41Surfaces, Substrates and Surface Preparation

Which hand-tool preparation standard is achieved when loose rust and scale are removed but tight mill scale and slight staining remain?

  1. St 2 Correct answer.
  2. Sa 1
  3. St 1
  4. St 3

Explanation

St 2 is the thorough hand and power tool cleaning grade in which loose mill scale, rust, and foreign matter are removed while tightly adherent scale may remain. St 1 is light cleaning only, St 3 is very thorough, and Sa grades refer to blasting rather than hand tools.

Question 42Surfaces, Substrates and Surface Preparation

Why must a previously painted surface be tested for lead before dry sanding?

  1. Lead prevents the new paint from drying
  2. Lead improves the adhesion of the new coat
  3. Lead makes the old paint easier to sand
  4. Lead dust is a health hazard and its presence changes the safe removal method Correct answer.

Explanation

Old paints, especially those applied before the 1970s, may contain lead pigments. Dry sanding generates inhalable lead dust that is toxic, so the removal method must be changed to wet methods or chemical stripping with proper controls. Lead does not improve adhesion or drying.

Question 43Surfaces, Substrates and Surface Preparation

Which method is used to check the cleanliness of a blast-cleaned steel surface for soluble salt contamination?

  1. Wet film thickness gauge
  2. Holiday detector
  3. Pull-off adhesion test
  4. Bresle patch test Correct answer.

Explanation

The Bresle patch extracts soluble salts from a defined area of the surface, and the extract is analysed by conductivity. High salt levels cause osmotic blistering under coatings. Wet film gauges, pull-off tests, and holiday detectors measure other properties.

Question 44Surfaces, Substrates and Surface Preparation

A painter is preparing aluminium for painting. Which preparation step is essential because of the natural oxide film on the metal?

  1. Washing with plain water
  2. Applying the topcoat directly
  3. Coating with grease to protect the surface
  4. Light abrading followed by a suitable etch or conversion treatment Correct answer.

Explanation

Aluminium forms a thin, stable oxide layer that prevents paint adhesion. Abrading and applying an etch or conversion coating replaces this layer with a receptive surface. Plain water does not remove the oxide, and grease would prevent bonding.

Question 45Surfaces, Substrates and Surface Preparation

Which statement correctly describes the purpose of a sealer coat on a porous plaster surface?

  1. It replaces the need for any surface cleaning
  2. It fills and evens absorption so the finish coat dries uniformly Correct answer.
  3. It provides the final colour and gloss
  4. It waterproofs the wall permanently

Explanation

Porous plaster absorbs binder unevenly, causing patchy gloss and colour. A sealer penetrates and evens the absorption so the finish coat cures uniformly. It is not the final decorative coat and does not eliminate cleaning.

Question 46Surfaces, Substrates and Surface Preparation

During abrasive blasting, the nozzle is held too far from the steel surface. What is the most likely result?

  1. The surface is polished rather than profiled
  2. The blast pattern widens and cleaning becomes inefficient Correct answer.
  3. A deeper anchor profile is produced
  4. The abrasive becomes finer and cuts faster

Explanation

Increasing nozzle distance spreads the abrasive stream and reduces impact energy, so cleaning is slower and the profile is shallower. Correct stand-off distance concentrates the blast for efficient cleaning. The stream does not become finer or polish the surface.

Question 47Surfaces, Substrates and Surface Preparation

Which type of surface contaminant is removed by solvent wiping rather than by abrasive blasting?

  1. Rust
  2. Old scale
  3. Mill scale
  4. Oil and grease Correct answer.

Explanation

Oil and grease are removed by solvents or alkaline degreasers because blasting would drive the contaminant into the surface. Mill scale and rust are solid deposits removed by blasting. Degreasing is normally done before blasting for this reason.

Question 48Surfaces, Substrates and Surface Preparation

A painter must prepare a large steel tank interior where blasting is prohibited. Which alternative preparation method is most suitable for achieving a high standard of cleanliness?

  1. Applying paint over the existing rust
  2. High-pressure water jetting with inhibitors Correct answer.
  3. Wiping with a dry rag
  4. Wire brushing by hand

Explanation

High-pressure water jetting can remove rust, scale, and soluble salts without generating sparks or abrasive dust, and inhibitors prevent flash rusting. Hand wire brushing is slow and reaches a lower standard, while wiping or painting over rust fails.

Question 49Surfaces, Substrates and Surface Preparation

What does the anchor profile of a blast-cleaned surface refer to?

  1. The distance between two welds
  2. The depth of the surface roughness created by the abrasive Correct answer.
  3. The thickness of the applied primer
  4. The angle at which the nozzle is held

Explanation

Anchor profile is the roughness depth produced by abrasive impact, usually measured in micrometres. It provides the mechanical key for the coating. It is unrelated to primer thickness, nozzle angle, or weld spacing.

Question 50Surfaces, Substrates and Surface Preparation

A painter notices that a new coat is crawling and pulling away from small areas on a steel panel. Which preparation fault is the most likely cause?

  1. Surface too rough from blasting
  2. Steel too cold
  3. Primer applied too thinly
  4. Patches of silicone or oil contamination Correct answer.

Explanation

Crawling and cratering occur when the paint cannot wet the surface because of low-surface-energy contamination such as silicone or oil. The coating pulls away from those spots. Roughness, thin film, and cold steel cause different defects.