Surface, color and limits of looking

Before teaching

• Choose actual school-approved products; read current labels/SDS and school requirements.

• Pilot the chosen hands-on method and document real failures, quantities, timings, drying/release and accessibility.

• Verify equipment, supervision, handling, waste and incident procedures.

• Apply lab-specific fallback whenever procurement, source visibility or safe-transfer conditions cannot be met.

Lab-specific review

• Use 0.10 mL in each 2 × 2 cm square, five comparable horizontal passes, order W1/K1/T1 then second and third sets. Do not add water to paint.

• The nine applications total 0.9 mL per group; the 5 mL allocation is for practical handling and losses, not required application.

• Keep initial label/surface records and all deviations; compare within-category replicates before categories.

Teacher preparation

For 30 students in ten groups of three, prepare thirty 8 × 10 cm pieces of each support, ninety pieces total. Supply ten brushes, ten needle-free 1 mL measures or sufficiently marked pipettes, ten palettes/wells, ten trays at least 30 × 35 cm, 1 L rinse water, labels and recording supplies, and five shared cool LED lamps. Allocate 50 mL of one ready-mixed blue tempera product/batch, with approximately 10 mL spare for setup and losses.

Nine applications of 0.10 mL consume 0.90 mL per group and 9 mL across ten groups in nominal deposited paint. The larger 5 mL group stock accommodates transfer losses and working access; it should not be poured onto the samples. Record actual use and avoid turning the stock allowance into a target for consumption.

Allow around 30 minutes to cut/label the class set and pilot at least one day ahead. Confirm that the measuring tool can reproducibly deliver 0.10 mL. If not, use teacher-measured equal portions or explicitly switch to qualitative observation. Prepare spare dry samples to accommodate uncertain drying without misrepresenting them as student results.

The three support types differ in several properties. “Support type” is the independent condition; paper color alone is not isolated. Compare repetitions before comparing categories. A follow-on experiment could keep one support and vary only measured paint amount, but it would need its own labeled question and protocol.

Use approved age-appropriate materials and follow actual labels and school rules. ASTM D-4236 indicates toxicological review, not edibility or absence of all hazards. Appropriate ACMI AP-labeled materials can assist selection. Exclude unknown donated paints, historic toxic pigments, dry powders, heating, ultraviolet sources, lasers, solvents, and chemical authenticity tests. No historical original or valued contemporary artwork is an experimental sample.

Historical evidence card

Provide an attributed paraphrase, not unlicensed journal figures: “The 1990 Huexotzinco conservation study distinguished two kinds of paper through microscopic comparison. The 2021 investigation combined microscopy and spectroscopy, and its yellow-dye discussion retained an unresolved identification. Visible hue alone would give less evidence for that identification.” Cite the Albro study and Villafana, Haude, and Satorius through source notes [4.1] and [4.4].

Schedule and equipment queues

First session 35–45 minutes, overnight or longer until dry, then second session 35–50 minutes. Current 13-step directions include a separate support-type comparison; no individual duration is specified for that step.

Alternative material plans

Use the accessible alternatives and fallback instructions in the student procedure.

Editorial corrections

The current student procedure is the teaching baseline.

Safety and stop conditions

Read these controls with the teacher before handling materials. Chemical etching is historical context only; the practical intaglio activity uses drypoint without mordants.

Controls

• Use pre-cut board and paper; any craft knife or guillotine is teacher-only, according to school policy.

• Use rounded scissors if students need a trimming step, and a capped pen or smooth plastic spoon rather than a sharp scoring tool.

• Do not boil bark, harvest tree bark, process animal skin, grind minerals, heat indigo–clay mixtures, use solvents, or handle dry pigment powders.

• Do not use historic pigments, cinnabar, orpiment, lead colours, unknown earths, or genuine antiquities. No open flame, UV lamp, lasers, acids, or chemical “authenticity tests.”

• No eating or drinking at the paint station. Wash hands; wipe spills promptly. Keep wet work away from screens and power supplies.

• Use a stable cool LED desk lamp for raking light; do not shine it into eyes. Never fold, wet, rub, scrape, or take a sample from an original manuscript or valued modern artwork.

• Record and follow individual allergy, sensory, motor, and vision accommodations. Do not ask pupils to disclose private health information to classmates.

Stop when

• Unknown or unsuitable art materials, discomfort, unsafe cutting, damaged tools, or unsafe wet/electrical setup: pause and follow school procedures.

• A source feature or matched historical scene is illegible or unverified: stop interpretive claims and use a labeled schematic or metadata exercise.

• Measuring tool cannot reliably measure 0.10 mL: use teacher-measured portions or explicitly switch to qualitative observation.

• Paint tacky on teacher test swatch: postpone physical examination; no heat gun.

Trained adult only

• Craft knives, guillotines, stock cutting, product selection, source/right checks, and permission-controlled photography.

Excluded activities

• Bark boiling or harvesting, skin processing, mineral grinding, heated indigo–clay mixtures, solvents, dry pigment powders, historic toxic pigments, genuine antiquities, flame, UV, lasers, acids, chemical authenticity tests.

• Sacred reenactment, unverified translation, automated completion of damaged signs, compulsory personal genealogy/migration/religion disclosure.

Cultural and source review

Specific specialist/practitioner review or permission is needed before claiming cultural endorsement or expanding into community-specific or restricted practice. No paid review, purchase, or spending is imposed as a blanket release gate for these explicitly labeled ordinary classroom adaptations. Do not claim any such consultation has occurred.