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Castilla-La Mancha PAU Técnicas de Expresión Gráfico-Plástica study materials
Castilla-La Mancha PAU Técnicas de Expresión Gráfico-Plástica study resources

Castilla-La Mancha PAU Técnicas de Expresión Gráfico-Plástica practice questions

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Question 1Graphic-plastic expression: materials, image-making and project evidence

What is the principal distinction between natural vine charcoal (carboncillo de sauce) and compressed charcoal (carboncillo comprimido)?

  1. Vine charcoal contains no added binders, making it soft and easily erasable, whereas compressed charcoal incorporates a binder to produce denser, darker, and less erasable marks Correct answer.
  2. Vine charcoal is bound with synthetic acrylic resin, making it completely insoluble in water once dry
  3. Compressed charcoal consists exclusively of calcined animal bone dust and leaves indelible oil stains on paper
  4. Vine charcoal cannot be smudged or blended using a tortillon or paper stump

Explanation

Natural vine charcoal is made by carbonizing willow or vine twigs in an oxygen-deprived kiln without any added binding agents. As a result, it deposits soft, friable carbon particles on paper that can be easily blended or erased. Compressed charcoal, by contrast, mixes powdered charcoal with a binder (such as gum or clay), producing a much darker, richer black line that adheres more stubbornly to the substrate.

Question 2Graphic-plastic expression: materials, image-making and project evidence

On the standard graphite pencil grading scale (H to B), what does a high 'B' rating (such as 6B or 8B) indicate?

  1. A high proportion of clay binder, yielding a very hard lead that creates light, precise lines
  2. A high ratio of graphite to clay binder, producing a soft lead that leaves dark, rich, and easily smudgeable marks Correct answer.
  3. The addition of microcrystalline wax, making the lead completely waterproof and non-erasable
  4. A standardized core diameter designed exclusively for technical orthographic projections

Explanation

The 'B' on the pencil grading scale stands for Blackness. High 'B' ratings signify a soft core with a higher concentration of graphite relative to the clay binder. This allows the pencil to deposit more graphite particles onto the paper with minimal pressure, producing deep black tones suitable for expressive shading.

Question 3Graphic-plastic expression: materials, image-making and project evidence

What is the mineral origin of the characteristic warm reddish-brown pigment found in traditional sanguine (sanguina)?

  1. Calcined cobalt oxide mixed with pulverized kaolin clay
  2. Synthetic cadmium seleno-sulfide ground with gum arabic
  3. Natural iron oxide (hematite), giving the drawing stick its earthy reddish-brown hue Correct answer.
  4. Organic madder root lake pigment precipitation

Explanation

Traditional sanguine (sanguina) is a dry drawing medium derived from earth pigments rich in natural iron oxide (hematite, Fe2O3). Its natural warm reddish-terracotta tone was extensively utilized by Renaissance masters for figure studies and naturalistic flesh rendering.

Question 4Graphic-plastic expression: materials, image-making and project evidence

How do soft dry pastels (pasteles secos) differ in binder content from oil pastels (pasteles al óleo)?

  1. Soft pastels use linseed oil as a binder, whereas oil pastels use water-soluble gum arabic
  2. Soft pastels are bound with animal hide glue, making them completely waterproof when dry
  3. Oil pastels contain no binders, relying solely on mechanical compression of dry chalk dust
  4. Soft pastels contain minimal water-soluble binder (such as gum tragacanth), while oil pastels use a non-drying wax and mineral oil binder Correct answer.

Explanation

Soft dry pastels consist of pure pigment mixed with just enough aqueous binder (gum tragacanth or methylcellulose) to hold the stick together, resulting in a velvety, powdery texture. Oil pastels use a non-drying mineral oil and wax binder, producing a creamy, buttery mark that does not crumble or generate powder.

Question 5Graphic-plastic expression: materials, image-making and project evidence

What is the primary function of applying a spray fixative (fijador) to a charcoal or dry pastel drawing?

  1. To bind loose pigment particles to the paper fibers, preventing accidental smudging during handling and storage Correct answer.
  2. To dissolve the graphite lead and transform the dry line into an indelible waterproof wash
  3. To increase paper absorbency so that subsequent oil paint layers can be applied without priming
  4. To bleach yellowed paper fibers back to bright archival white without altering color values

Explanation

Spray fixatives contain resin dissolved in an evaporating solvent. When sprayed lightly over dry charcoal, chalk, or pastel drawings, the resin forms a fine protective film that anchors the powdery pigment particles to the paper fibers, preventing smudging.

Question 6Graphic-plastic expression: materials, image-making and project evidence

Why does silverpoint (punta de plata) drawing require a specially prepared ground (such as traditional gesso or bone ash coating)?

  1. Silver is too soft to mark smooth paper without a wax coat
  2. The abrasive texture of the grounded surface abrades tiny metal particles off the silver wire, leaving a visible line Correct answer.
  3. Untreated paper chemically dissolves the silver stylus upon contact
  4. Silverpoint relies on water absorption to activate the metal oxidation process

Explanation

Silver wire drawn across bare paper leaves almost no mark because smooth paper lacks sufficient tooth to abrade the metal. A slightly abrasive ground containing bone ash, zinc white, or gesso drags micro-particles off the metal stylus, leaving a delicate silver line on the ground.

Question 7Graphic-plastic expression: materials, image-making and project evidence

What components constitute traditional Conté crayons (lápices o barritas Conté), invented by Nicolas-Jacques Conté in 1795?

  1. Paraffin wax and synthetic aniline dyes mixed under high pressure
  2. Pure calcium carbonate mixed with linseed oil and varnish
  3. Micro-pulverized graphite or iron oxide pigment mixed with clay binder and compressed into square sticks Correct answer.
  4. Charred vine shoots bound with gum arabic and shellac

Explanation

Conté crayons were invented in 1795 as a response to graphite shortages. Nicolas-Jacques Conté combined finely ground graphite or natural earth pigments (iron oxides for sanguine and sepia) with a clay binder, baking the mixture into square sticks that offered controlled hardness and rich tone.

Question 8Graphic-plastic expression: materials, image-making and project evidence

Which tool is specifically designed for creating smooth tonal gradations (sfumato) and blending dry graphite or charcoal marks?

  1. A steel burnisher with a polished curved tip
  2. A stiff hog bristle fan brush
  3. A rubber brayer roller
  4. A tortillon or paper stump (difumino) made of tightly rolled paper Correct answer.

Explanation

A tortillon or paper stump (difumino) is a cylindrical drawing tool crafted from tightly rolled felted paper. Its pointed tip allows artists to smudge, soften, and blend dry medium particles (graphite, charcoal, sanguine) across the paper, creating continuous tonal transitions.

Question 9Graphic-plastic expression: materials, image-making and project evidence

Why are oil pastels (pasteles al óleo) chemically incompatible with water-based washes, but responsive to mineral spirits?

  1. Because their wax and mineral oil binder repels water (hydrophobic) but dissolves in organic hydrocarbon solvents Correct answer.
  2. Because they contain water-soluble gum arabic that hardens when exposed to petroleum distillates
  3. Because the pigment particles are magnetized and only move under alcoholic vapor pressure
  4. Because mineral spirits turn the oil pastel into an insoluble acrylic film

Explanation

Oil pastels utilize non-drying mineral oil and paraffin wax binders. Water is repelled by these non-polar hydrophobic substances (a property exploited in resist techniques). Organic solvents like mineral spirits or turpentine dissolve the wax/oil matrix, allowing oil pastel marks to be washed and blended like oil paint.

Question 10Graphic-plastic expression: materials, image-making and project evidence

How does paper tooth (grano del papel) influence the physical application of dry charcoal and pastel media?

  1. A smooth hot-pressed surface holds more pastel layers than a rough surface
  2. A pronounced tooth provides microscopic valleys that physically trap friable pigment particles, permitting heavy layering Correct answer.
  3. Tooth chemically binds pigment to cellulose without requiring mechanical friction
  4. Paper tooth only affects water absorption and has zero mechanical impact on dry drawing media

Explanation

The 'tooth' (grano) refers to the surface texture of paper. Rough or cold-pressed papers have pronounced surface valleys that mechanically shear and trap dry pigment particles from charcoal or pastel sticks. Smooth (hot-pressed) papers lack tooth and quickly become saturated, resisting further layering.

Question 11Graphic-plastic expression: materials, image-making and project evidence

What historical organic source provided the dark brown ink and drawing pigment traditionally known as sepia (jibia/sepia)?

  1. Fermented oak gall nuts combined with iron sulfate solution
  2. Charred coconut shells pulverized in walnut oil
  3. The dried ink sac of the cuttlefish (Sepia officinalis) Correct answer.
  4. Precipitated soot from coal combustion gas

Explanation

Authentic historical sepia pigment is derived from the ink sac of the cuttlefish (Sepia officinalis). The ink sac was extracted, dried, ground, and dissolved in dilute alkali to create a rich, warm brown ink and wash medium widely used by 18th and 19th-century artists.

Question 12Graphic-plastic expression: materials, image-making and project evidence

How does a kneaded rubber eraser (goma moldeable / miga de pan) function differently from a vinyl block eraser when lifting graphite?

  1. It abrades paper fibers with coarse pumice particles to cut away deep marks
  2. It dissolves graphite chemically using synthetic alcohol additive
  3. It melts paper sizing using friction heat to seal graphite beneath the surface
  4. It lifts graphite particles by adhesion without abrading or tearing paper fibers Correct answer.

Explanation

A kneaded eraser is a pliable, putty-like rubber tool that absorbs graphite particles by surface adhesion when pressed onto paper. Unlike rigid vinyl erasers, it does not abrade paper fibers or produce eraser crumbs, allowing subtle highlight lifting without damaging delicate paper grounds.

Question 13Graphic-plastic expression: materials, image-making and project evidence

Why must spray fixative be applied in multiple light, distance-controlled passes rather than a single heavy coat over dry pastels?

  1. A heavy coat saturates the dry pigment particles, changing their refractive index and causing dramatic darkening and loss of luminosity Correct answer.
  2. Fixative causes pure cotton paper to shrink instantly by more than 20% if applied heavily
  3. Heavy fixative coats ignite spontaneously when contacting ambient oxygen
  4. Dry pastels chemically dissolve into toxic ammonia gas when wet with heavy resin

Explanation

Dry pastels owe their intense brilliance to the reflection of light off dry, unencapsulation pigment grains surrounded by air. Heavy liquid fixative fills the air gaps between pigment particles with resin, altering the refractive index and severely darkening colors, flattening texture, and dulling brilliance.

Question 14Graphic-plastic expression: materials, image-making and project evidence

In Renaissance drawing practice, what was the primary application of sanguine combined with white chalk on toned paper (dossier / papel coloreado)?

  1. Creating waterproof maps for nautical navigation
  2. Executing three-tone (trois crayons) chiaroscuro studies to model light, shadow, and midtones of the human body Correct answer.
  3. Etching metal copper plates for relief printing editions
  4. Sizing raw linen canvases before applying oil washes

Explanation

The technique of using red sanguine, black chalk/charcoal, and white chalk on toned paper (known as 'trois crayons') enabled Renaissance masters like Leonardo and Michelangelo to establish warm midtones (toned paper), deep shadows (sanguine/black chalk), and bright highlights (white chalk) efficiently.

Question 15Graphic-plastic expression: materials, image-making and project evidence

How is powdered graphite (grafito en polvo) typically applied to achieve broad, seamless tonal gradients across large drawing surfaces?

  1. By baking the powder onto paper with an electric iron
  2. By dissolving it in nitric acid and applying with an airbrush
  3. Using a soft chamois cloth, cotton wad, or blending stump to rub the dry powder into paper tooth Correct answer.
  4. Mixing it with linseed oil to form an indelible impasto paste

Explanation

Powdered graphite is an un-bound dry medium. It is applied by dipping a soft dry applicator-such as a chamois cloth, felt stump, or soft brush-into the powder and rubbing it in circular motions onto paper, creating smooth atmosphere and subtle value transitions.

Question 16Graphic-plastic expression: materials, image-making and project evidence

Why does a 9H graphite pencil leave a lighter line than an HB pencil under identical hand pressure?

  1. 9H pencils contain 100% pure graphite without any clay additive
  2. 9H leads are infused with titanium dioxide white pigment to dilute blackness
  3. 9H leads are baked at lower temperatures so graphite remains un-calcined
  4. 9H pencils contain a much higher ratio of hard clay binder relative to graphite, yielding a dense core that deposits fewer carbon particles Correct answer.

Explanation

Pencil lead hardness is controlled by the clay-to-graphite ratio. A 9H pencil has a very high clay content baked into a rigid matrix. Because the core is extremely hard, it resists wearing down, depositing only tiny amounts of light gray graphite onto paper.

Question 17Graphic-plastic expression: materials, image-making and project evidence

What chemical transformation causes historical silverpoint drawings to gradually change color from a pale gray to a warm warm brown over years of atmospheric exposure?

  1. Tarnishing/oxidation of tiny silver particles reacting with airborne sulfur to form silver sulfide (Ag2S) Correct answer.
  2. Decay of bone ash ground into calcium nitrate crystals under sunlight
  3. Polymerization of residual animal glue binder turning yellow
  4. Reduction of lead white pigment into elemental metallic lead

Explanation

When silver metal particles deposited by silverpoint contact ambient air containing hydrogen sulfide or sulfur compounds, they undergo chemical tarnishing (sulfuración), forming silver sulfide (Ag2S). This converts the initial cool gray line into the characteristic warm golden-brown patina seen on master Renaissance drawings.

Question 18Graphic-plastic expression: materials, image-making and project evidence

In conservation science, why is liquid spray fixative application generally avoided on museum-grade historical pastel masterpieces?

  1. Fixatives dissolve cotton rag paper cellulose within 24 hours of exposure
  2. Irreversible changes to optical light scattering alter original color values, and aging resins yellow and embrittle over time Correct answer.
  3. Fixative resins attract subterranean termites that consume paper supports
  4. Spray resins react with pastel pigments to generate corrosive sulfuric acid

Explanation

Conservators avoid fixatives on fine pastels because any liquid resin alters the air-pigment interface, permanently changing light scattering and darkening delicate tints. Furthermore, synthetic fixative resins yellow, embrittle, and become insoluble as they age, violating the core conservation principle of reversibility.

Question 19Graphic-plastic expression: materials, image-making and project evidence

What micro-physical force binds un-bound dry charcoal particles to paper fibers prior to fixative application?

  1. Covalent chemical bonding between carbon atoms and paper cellulose
  2. Electrostatic attraction combined with mechanical entrapment within paper tooth micro-structures
  3. Capillary action of paper moisture dissolving carbon into solution Correct answer.
  4. Magnetic alignment of carbon electron spins under atmospheric pressure

Explanation

Un-bound charcoal relies on mechanical entrapment inside the microscopic valley structures (tooth) of paper fibers, reinforced by weak Van der Waals and electrostatic forces. Because no chemical or binder bond exists, the particles remain vulnerable to physical displacement until fixed.

Question 20Graphic-plastic expression: materials, image-making and project evidence

What specific greasy ingredients distinguish lithographic crayons (lápices litográficos) from standard dry drawing pencils?

  1. Gum arabic, honey, and glycerin dissolved in water
  2. Polyvinyl acetate emulsion and titanium dioxide powder
  3. Tallow, beeswax, soap, and shellac combined with lampblack pigment Correct answer.
  4. Linseed stand oil mixed with turpentine spirit and cobalt drier

Explanation

Lithographic crayons are formulated specifically to deposit hydrophobic greasy marks onto limestone or aluminum litho plates. They consist of soap, beeswax, tallow (mortero/sebo), shellac, and lampblack. The soap and fat components chemically bond with the stone matrix to create grease-receptive printing areas.

Question 21Graphic-plastic expression: materials, image-making and project evidence

What is the natural water-soluble binder traditionally used in fine artist watercolor (acuarela)?

  1. Gum arabic (goma arábiga), harvested from Acacia trees Correct answer.
  2. Refined linseed oil extracted from flax seeds
  3. Acrylic polymer emulsion diluted with alcohol
  4. Egg yolk emulsified with distilled vinegar

Explanation

Watercolor relies on gum arabic (goma arábiga) as its primary binder. Gum arabic is a water-soluble natural gum derived from Acacia trees. It holds pigment particles in suspension, binds them to paper, and remains re-wettable with water even after drying completely.

Question 22Graphic-plastic expression: materials, image-making and project evidence

What key ingredient gives gouache (tempera/guache) its characteristic opaque matte appearance compared to transparent watercolor?

  1. High concentration of clear dammar varnish
  2. An added inert white pigment filler (such as chalk or titanium white) and higher pigment load Correct answer.
  3. Liquid latex rubber solution that seals light rays
  4. Boiled linseed oil added during cold grinding

Explanation

Gouache is an opaque water-based paint. It shares a gum arabic binder with watercolor but includes inert white chalk (calcium carbonate) or blanc fixe fillers along with a much higher pigment ratio. This prevents light from passing through to the paper, creating an opaque, matte paint film.

Question 23Graphic-plastic expression: materials, image-making and project evidence

What synthetic polymer medium serves as the binder in modern acrylic paints (pintura acrílica)?

  1. Nitrocellulose lacquer resin
  2. Phenol-formaldehyde resin
  3. Acrylic polymer resin emulsion (emulsión de polímero acrílico) Correct answer.
  4. Polyurethane varnish dispersion

Explanation

Acrylic paint consists of mineral or synthetic pigments suspended in a water-soluble acrylic polymer resin emulsion. As the water evaporates during drying, the polymer microscopic spheres coalesce into a tough, flexible, water-insoluble plastic film.

Question 24Graphic-plastic expression: materials, image-making and project evidence

What is the primary drying oil traditionally used as a binder in fine art oil painting (pintura al óleo)?

  1. Mineral motor oil
  2. Petroleum jelly (vaseline)
  3. Non-drying olive oil
  4. Linseed oil (aceite de linaza) Correct answer.

Explanation

Cold-pressed or alkali-refined linseed oil (extracted from flax seeds, Linum usitatissimum) is the most widely used drying oil binder in oil paint. It dries not by evaporation, but by chemical oxidation and cross-linking (polymerization) when exposed to air.

Question 25Graphic-plastic expression: materials, image-making and project evidence

What does the fundamental rule of oil painting 'fat over lean' (graso sobre magro) stipulate?

  1. Each successive paint layer should contain a higher proportion of oil ('fat') than the underlying layer ('lean') Correct answer.
  2. Underlayers must be diluted with heavy varnish, while top layers are thinned with pure turpentine
  3. Fast-drying water-based paints must always be applied over slow-drying oil paints
  4. Smooth canvas supports must be coated with lard before painting

Explanation

The 'fat over lean' rule requires that lower paint layers contain less oil (thinned with solvent / lean) and upper layers contain more oil (fat). Because oil-rich layers dry more slowly and remain more flexible, putting a fast-drying, inflexible lean layer on top of a slow-drying fat layer causes severe cracking (craquelure) and flaking.

Question 26Graphic-plastic expression: materials, image-making and project evidence

Which watercolor technique involves applying wet paint onto a paper surface that is already saturated with clean water?

  1. Dry brush (pincel seco)
  2. Wet-on-wet (húmedo sobre húmedo) Correct answer.
  3. Scraping / sgraffito (rascado)
  4. Glazing (veladura seca)

Explanation

The wet-on-wet (húmedo sobre húmedo) technique entails wetting the paper with clean water before introducing fluid watercolor. The pigment bleeds, diffuses, and spreads organically across the damp fibers, yielding soft edges and atmospheric gradients.

Question 27Graphic-plastic expression: materials, image-making and project evidence

What is a 'glaze' (veladura) in traditional painting practice?

  1. A thick, opaque coat of white paint applied to obscure previous mistakes
  2. A layer of ground ceramic silica baked in an industrial kiln
  3. A thin, transparent or semi-transparent paint layer applied over a dry, lighter base layer to alter its color tone without obscuring details Correct answer.
  4. A textured paste mixed with sand to build relief structures

Explanation

A glaze (veladura) is a thin, translucent layer of paint thinned with medium. When applied over a dry, lighter underpainting (such as a monochrome grisaille), light travels through the glaze, reflects off the underlayer, and returns to the viewer's eye, creating luminous, optical color depth.

Question 28Graphic-plastic expression: materials, image-making and project evidence

Which tool or technique is used to create heavy, raised physical textures and thick paint relief (empaste) on canvas?

  1. Diluting paint with 90% turpentine and applying with a soft mop brush
  2. Spraying liquid paint with an airbrush
  3. Applying thinned ink with a drafting pen
  4. Applying un-thinned paint heavily using a palette knife (esátula) or stiff bristle brush (empaste / impasto) Correct answer.

Explanation

Impasto (empaste) is the technique of laying paint on thickly so that brushstrokes or palette knife marks remain clearly visible in relief. Palette knives (espátulas) allow artists to apply buttery oil or heavy-body acrylic paint directly to build sculptural surface textures.

Question 29Graphic-plastic expression: materials, image-making and project evidence

How do spirits of turpentine (esencia de trementina) and odorless mineral spirits (esencia mineral inodora) function in traditional oil painting?

  1. They act as volatile solvents that thin oil paint viscosity, dissolve resins, and clean brushes by evaporating completely Correct answer.
  2. They act as permanent synthetic binders that convert linseed oil into acrylic plastic
  3. They act as aqueous emulsifiers that allow oil paint to mix seamlessly with watercolor
  4. They act as chemical retarders that extend oil drying time by several months

Explanation

Turpentine and mineral spirits are volatile organic solvents. They reduce the viscosity of oil paint (making it 'leaner'), dissolve varnish resins (like dammar), and clean oil residue from brushes. They evaporate entirely into the air, leaving behind only the oil and pigment film.

Question 30Graphic-plastic expression: materials, image-making and project evidence

What is the key composition of traditional egg tempera (temple al huevo) emulsion?

  1. Boiled egg whites mixed with synthetic varnish and mineral oil
  2. Egg yolk emulsified with distilled water and dry powdered pigment Correct answer.
  3. Whole powdered eggs dissolved in pure ethanol and shellac
  4. Eggshell powder ground with gum arabic and turpentine

Explanation

Traditional egg tempera uses fresh egg yolk as a natural emulsion of water, egg lipids (fats), and lecithin (an emulsifying agent). When mixed with distilled water and dry ground pigment, it forms a fast-drying medium that cures into a durable, satin-matte paint film.

Question 31Graphic-plastic expression: materials, image-making and project evidence

What chemical reaction causes true fresco (buon fresco) to permanently lock pigments into a plaster wall surface?

  1. Evaporation of alcohol solvents leaving behind a plastic acrylic shell
  2. Thermal fusion of wax and dammar resin under direct flame heating
  3. Carbonatization: Slaked lime (calcium hydroxide) in wet plaster absorbs atmospheric carbon dioxide to form insoluble calcium carbonate (limestone) Correct answer.
  4. Acid hydrolysis of casein proteins forming an insoluble glue network

Explanation

In buon fresco, water-based pigments are painted directly onto freshly laid wet lime plaster (intonaco). As the slaked lime (Ca(OH)2) dries, it reacts with CO2 in the air to form calcium carbonate (CaCO3). This chemical process (carbonatization) encapsulates pigment particles inside the crystalline structure of the wall.

Question 32Graphic-plastic expression: materials, image-making and project evidence

Why is traditional Indian ink (tinta china) waterproof after drying, whereas standard fountain pen fountain ink remains water-soluble?

  1. Indian ink uses oil-soluble synthetic aniline dyes that repel moisture
  2. Indian ink is mixed with nitric acid that etches into paper cellulose
  3. Indian ink contains synthetic silicone polymers that form a rubber barrier
  4. Indian ink incorporates shellac (gomalaca) or natural varnish as a binder, which becomes water-insoluble upon drying Correct answer.

Explanation

Traditional liquid Indian ink consists of fine carbon black (negro de humo) suspended in water with a binder of shellac (gomalaca) solubilized in borax or ammonia. Once dry, the shellac forms an insoluble resin film that resists water. Fountain pen inks use water-soluble dye solutions without shellac to prevent clogging internal feeds.

Question 33Graphic-plastic expression: materials, image-making and project evidence

How is masking fluid (frisket / látex líquido) utilized in watercolor painting to preserve white highlights?

  1. It is painted onto dry paper to form a liquid-proof rubber barrier, allowing washes to be painted over it before being peeled away Correct answer.
  2. It is mixed directly into watercolor paint to increase its drying speed and opacity
  3. It is sprayed over finished paintings to permanently seal watercolor against UV light
  4. It is applied to the back of paper to prevent water buckling

Explanation

Masking fluid is a liquid rubber latex compound. Painted onto dry watercolor paper, it seals target areas so wet washes can be applied freely overhead without staining the preserved paper underneath. Once the surrounding wash is dry, the latex film is rubbed or peeled off to reveal crisp white paper.

Question 34Graphic-plastic expression: materials, image-making and project evidence

What is the function of adding an acrylic retarder medium (retardador de secado) to acrylic paints?

  1. It speeds up polymer drying so second coats can be applied in seconds
  2. It slows down water evaporation, extending open blending time on canvas Correct answer.
  3. It converts water-soluble acrylic into an oil paint that requires turpentine cleanup
  4. It bleaches dark acrylic pigments into pastel shades

Explanation

Acrylic paints dry rapidly as water evaporates. Acrylic retarders contain glycol additives that slow the rate of water evaporation and delay polymer film formation, giving artists extra 'open time' for wet-on-wet blending, soft shading, and smooth transitions.

Question 35Graphic-plastic expression: materials, image-making and project evidence

How do poppyseed oil (aceite de adormidera) and walnut oil (aceite de nuez) compare to linseed oil regarding yellowing tendencies in oil paints?

  1. Poppyseed and walnut oil yellow significantly more than linseed oil, making them unsuitable for whites
  2. Linseed oil never yellows, whereas poppyseed oil turns black under ambient light
  3. Poppyseed and walnut oils yellow less than linseed oil, making them preferable for pale blues and whites despite drying more slowly Correct answer.
  4. All three oils exhibit identical drying times and zero yellowing characteristics

Explanation

Linseed oil contains high levels of linolenic fatty acid, which causes it to dry quickly into a tough film but also leads to noticeable yellowing over time. Poppyseed and walnut oils contain lower linolenic acid levels, so they yellow significantly less-making them ideal for grinding whites and pale blues-though they form a slower-drying, slightly weaker paint film.

Question 36Graphic-plastic expression: materials, image-making and project evidence

What is the primary binder and application mechanism in traditional encaustic painting (encáustica)?

  1. Liquid acrylic resin sprayed cold through a pressurized gun
  2. Gum tragacanth mixed with water and applied with sable brushes
  3. Linseed oil thinned with acetone and dried under UV lamps
  4. Molten beeswax combined with dammar resin, kept fluid with heat and fused onto the panel using thermal tools Correct answer.

Explanation

Encaustic painting is an ancient technique (seen in Fayum mummy portraits) using molten beeswax and dammar resin mixed with pigment. The paint must be kept hot while being applied to a rigid wooden panel, and each added layer is thermally fused ('encausticos' = burned in) with a heat source.

Question 37Graphic-plastic expression: materials, image-making and project evidence

What defines the 'wash' (aguada) technique in ink and watercolor media?

  1. Diluting ink or pigment heavily with water to cover large areas with flat or graded translucent tones Correct answer.
  2. Scraping off dry paint layers with a razor blade to reveal white paper
  3. Applying thick, undiluted paste directly from the tube with a trowel
  4. Sealing a finished drawing with a waterproof varnish coat

Explanation

A wash (aguada) is created by diluting water-based ink or watercolor pigment with significant amounts of water. It is swept across paper using a large brush to produce uniform (flat wash) or gradually fading (graded wash) translucent tone.

Question 38Graphic-plastic expression: materials, image-making and project evidence

What defect occurs when an upper oil paint layer loses oil to an absorbent underlayer, resulting in dull, matte, lifeless patches known as 'sinking in' (rechupe)?

  1. The paint film turns into liquid watercolor and washes off
  2. Oil binder is sucked down into an porous ground or lean underlayer, leaving surface pigment under-bound and dull Correct answer.
  3. Pigment particles explode due to localized heat concentration
  4. Canvas fibers contract instantly and tear the stretcher frame

Explanation

Sinking in (rechupe) occurs when the oil binder in a fresh layer of paint is drawn down by capillary action into a porous, absorbent ground or an unsealed, lean underlayer. This leaves the surface paint film starved of binder, producing flat, dull, uneven matte patches (remedied with retouching varnish).

Question 39Graphic-plastic expression: materials, image-making and project evidence

Why can dry gouache paint layers be re-wetted and reworked with water, whereas dry acrylic paint layers cannot?

  1. Gouache uses a synthetic vinyl binder that melts in cold water
  2. Acrylic paint contains linseed oil which cures into a soluble soap
  3. Gouache uses water-soluble gum arabic binder that remains soluble, whereas acrylic polymer emulsion undergoes irreversible coalescence into a water-resistant film Correct answer.
  4. Gouache contains alcohol solvents that evaporate slowly over 50 years

Explanation

Gouache relies on gum arabic, a water-soluble natural carbohydrate polymer that readily re-dissolves when touched with water even after years of drying. Acrylic paint uses a synthetic resin emulsion whose polymer spheres fuse permanently (coalesce) as water evaporates, creating an irreversible, waterproof plastic matrix.

Question 40Graphic-plastic expression: materials, image-making and project evidence

What is the primary protein constituent used as a natural binder in casein paint (pintura a la caseína)?

  1. Wheat gluten extracted from flour
  2. Collagen derived from boiled fish bones
  3. Gelatin extracted from animal hooves
  4. Casein protein, precipitated from skimmed milk using acid or rennet Correct answer.

Explanation

Casein paint is an ancient water-based medium utilizing casein, a phosphoprotein isolated from skimmed milk. Dissolved in an alkaline agent (such as lime or ammonium carbonate), casein forms a strong, fast-drying binder that dries to a velvety, highly durable matte finish.

Question 41Graphic-plastic expression: materials, image-making and project evidence

What two-stage physical-chemical process governs the drying and film-formation of acrylic polymer paint?

  1. Initial physical water evaporation followed by irreversible polymer particle coalescence into a continuous film Correct answer.
  2. Chemical oxidation of fatty acids followed by ultraviolet radiation cross-linking
  3. Sublimation of solid solvents followed by crystalline precipitation of calcium carbonate
  4. Thermal vitrification followed by acid hydrolysis

Explanation

Acrylic paint dries in two distinct phases: first, water and volatile additives evaporate, packing the suspended acrylic polymer spheres tightly together. Second, the polymer spheres deform and coalesce (capillary fusion), interweaving their polymer chains into an irreversible, flexible, water-resistant film.

Question 42Graphic-plastic expression: materials, image-making and project evidence

How is stand oil (aceite polimerizado / standoil) manufactured, and what unique working qualities does it confer when mixed into oil glazes?

  1. It is extracted from cold-pressed olives and produces a completely matte, powdery chalk surface
  2. It is prepared by heating linseed oil at high temperatures (approx. 300°C) in an oxygen-free environment, creating a thick, honey-like oil that enhances gloss, leveling, and yellowing resistance Correct answer.
  3. It is created by boiling oil with sulfuric acid to increase water solubility
  4. It is frozen at sub-zero temperatures to separate wax crystals for fast dry-brush painting

Explanation

Stand oil is produced by heating linseed oil to around 300°C in an anaerobic (vacuum/nitrogen) environment. This thermally polymerizes the oil without oxidation, yielding a viscous, enamel-like oil. When used in glazing mediums, it levels out brushstrokes, increases gloss and depth, and resists yellowing far better than raw linseed oil.

Question 43Graphic-plastic expression: materials, image-making and project evidence

What structural stress mechanism causes severe craquelure and peeling when a fast-drying, inflexible paint coat (magro) is applied over a slow-drying, oil-rich underlayer (graso)?

  1. The lean top layer dries and contracts quickly into a brittle skin while the flexible fat underlayer continues to expand and shift underneath, rupturing the top coat Correct answer.
  2. The fat underlayer releases high-pressure steam that shatters the top coat
  3. The top coat absorbs all atmospheric nitrogen and turns into liquid ammonia
  4. The lean coat chemically dissolves the underlying canvas cotton fibers

Explanation

When a fast-drying, inflexible lean coat sits on top of a soft, slow-drying, oil-rich underlayer, the top layer skin cures and contracts first. As the flexible underlayer slowly oxidizes, expands, and moves over subsequent months, it generates shear stress that splits the rigid upper coat, creating deep cracks (craquelure) and adhesion failure.

Question 44Graphic-plastic expression: materials, image-making and project evidence

What molecular characteristic of gum arabic enables it to act as both a stabilizer for wet watercolor pigments in suspension and a re-wettable binder upon drying?

  1. Its long, branched polysaccharide chains contain abundant hydroxyl groups that bind water molecules without forming cross-linked chemical covalent bonds Correct answer.
  2. Its linear hydrocarbon chains form permanent vulcanized rubber bonds
  3. Its metallic ion core generates magnetic fields that trap pigment molecules
  4. Its hydrophobic lipid structure repels moisture completely once dry

Explanation

Gum arabic is a complex mixture of arabinogalactan oligosaccharides and glycoproteins. Its heavily branched polysaccharide structure contains numerous polar hydroxyl (-OH) groups that readily form hydrogen bonds with water. Because these bonds are non-covalent physical interactions, water easily re-hydrates the dried matrix.

Question 45Graphic-plastic expression: materials, image-making and project evidence

How do chemical driers (secantes catalytic driers like cobalt or manganese naphthenates) accelerate the curing rate of linseed oil paint?

  1. They act as oxidation catalysts that speed up the uptake of atmospheric oxygen and decomposition of peroxides to form cross-linked polymer networks Correct answer.
  2. They absorb all water vapor from the studio air instantly
  3. They evaporate the linseed oil binder within 5 minutes
  4. They convert pigment particles into heat energy that bakes the paint

Explanation

Liquid driers (secantes) contain metal salts (cobalt, manganese, or zirconium). Cobalt acts as a surface drier by catalyzing the absorption of atmospheric oxygen across double bonds in unsaturated fatty acids, accelerating peroxide formation and cross-linking polymerization.

Question 46Graphic-plastic expression: materials, image-making and project evidence

In relief printmaking (grabado en relieve), from which part of the matrix is ink transferred onto paper during printing?

  1. Deeply carved gouge marks and cut grooves
  2. The raised, uncarved surface areas of the block Correct answer.
  3. Etched microscopic dots located below the main surface
  4. A porous mesh screen clamped over the block

Explanation

Relief printing (such as woodcut or linocut) is defined by cutting away unwanted background areas from a matrix. Ink is applied with a roller only to the raised, uncarved surface areas, which then transfer the image onto paper under pressure.

Question 47Graphic-plastic expression: materials, image-making and project evidence

Which major category of printmaking includes techniques such as etching, drypoint, aquatint, and burin engraving?

  1. Relief printing (grabado en relieve)
  2. Planographic printing (litografía)
  3. Intaglio printing (grabado en hueco / calcografía) Correct answer.
  4. Stencil printing (serigrafía)

Explanation

Intaglio printing (calcografía / grabado en hueco) encompasses all processes where the image is incised or etched into a metal plate (copper, zinc). Ink is wiped into the recessed lines/grooves, the surface is wiped clean, and heavy pressure forces damp paper into the recesses to pick up the ink.

Question 48Graphic-plastic expression: materials, image-making and project evidence

What chemical principle governs planographic printmaking (litografía)?

  1. The physical cutting of raised wooden relief blocks
  2. The thermal melting of wax crayons onto damp silk
  3. The chemical corrosion of zinc plates in nitric acid baths
  4. The natural chemical antipathy and mutual repulsion between oil/grease and water Correct answer.

Explanation

Lithography is a planographic process (printing from a flat surface). It relies on the chemical principle that oil and water do not mix. Greasy drawing areas on a flat limestone or aluminum plate attract oil-based printing ink while repelling water, while damp non-image areas retain water and repel ink.

Question 49Graphic-plastic expression: materials, image-making and project evidence

In serigraphy (serigrafía / screen printing), how is ink forced through the open areas of the mesh screen onto the substrate?

  1. Using a rubber squeegee (racleta) scraped across the screen mesh Correct answer.
  2. Using a high-pressure heavy steel rolling press (tórculo)
  3. Using a wooden baren rubbed in circular hand motions
  4. Using a heated copper iron

Explanation

Serigraphy (screen printing) relies on a woven fabric mesh stretched over a frame. Stencils block non-printing areas. Ink is poured onto the screen and forced through the open unblocked mesh apertures onto paper or fabric below using a flexible rubber squeegee blade (racleta).

Question 50Graphic-plastic expression: materials, image-making and project evidence

How does woodcut on side-grain plank wood (xilografía a fibra) differ from wood engraving on end-grain wood (xilografía a testa / al boj)?

  1. Side-grain woodcut uses acid baths, whereas end-grain uses litho stone
  2. Side-grain plank wood follows long grain directions limiting ultra-fine detail, whereas end-grain wood (like boxwood) presents a hard, uniform surface allowing ultra-fine line engraving in any direction Correct answer.
  3. End-grain wood engraving requires rubber squeegees instead of rollers
  4. Side-grain woodcut produces intaglio prints, whereas end-grain produces planographic prints

Explanation

Plank-grain woodcut (a fibra) cuts parallel to tree growth, where long fibers resist delicate cross-cutting and yield broader marks. End-grain wood engraving (a testa, typically using boxwood / boj) offers a hard, dense, grain-free surface that permits delicate, razor-thin lines engraved in any direction with a burin.