Cleaning, Preparation and Material Processing
Collected waste becomes raw material only after it is cleaned, dismantled, dried and processed. This domain tests the correct order of operations and a few standard recipes.
Standard processing sequence
- Sort and dismantle - remove caps, rings, labels, staples, tape and non-working parts.
- Wash in warm water with dish soap; brush out corrugations.
- De-label: soak ten minutes, scrape with a plastic scraper, soften adhesive with cooking oil or warm soapy water.
- Disinfect bottles meant for planters with a dilute bleach solution, then rinse thoroughly.
- Dry in shade, not direct sun - sun warps plastic and cockles paper.
- Key the surface with 80–120 grit paper so glue and paint grip.
- Store in labelled, dry crates.
Material-specific notes
- Tin cans: remove both ends, file the burr, degrease, then apply metal primer.
- Cardboard: peel tape, flatten, note the flute direction - strength runs along the flutes.
- Fabric: wash, iron, cut on the grain, seal raw edges.
- Coconut shell: strip fibre, sand 80 then 120 grit, dry before finishing.
- Papier-mâché: strip method uses one part PVA to one part water; pulp uses one part flour to three parts water cooked to a paste.
Worked example
For 500 g of pulp, soak 200 g shredded newspaper for 12 hours, squeeze out the water, mix in 100 g flour, 20 g salt and enough water to blend, then strain. Reasoning: squeezing out excess water prevents shrinkage cracks, and the salt inhibits mould in a humid climate.
Traps
Gluing onto a wet or oily surface; skipping degreasing on tin; drying in strong sun; building pulp thicker than about 10 mm per layer, which cracks as it dries; storing processed material in an unventilated cupboard.