Surface Finishing, Colouring and Decoration
Surface finishing decides whether a piece looks bought or broken. This domain tests preparation, product choice, application and decoration technique.
Preparation comes first
Sand in sequence: 80, 120, 240 grit. Dust off with a dry cloth. Fill dents with putty and sand flush. Seal paper and cardboard with PVA size or primer; prime metal with a metal primer. Paint does not hide a bad surface, it magnifies it.
Choosing the finish
- Acrylic emulsion: water-based, low odour, fast drying - indoor wood, paper and board.
- Enamel: solvent-based, hard, weather-resistant - outdoor metal.
- Varnish or lacquer: clear protective coat over colour, needed for planters, coasters and anything handled.
- Natural options: linseed oil, beeswax polish, dyes from turmeric, beetroot, tea and indigo.
Applying
Two thin coats beat one thick coat. Let each coat dry, sand lightly with 400 grit, dust, then recoat. Mask edges with tape for straight lines. Work in shade, away from humidity and dust.
Decoration techniques
Decoupage with a glue medium and three sealing coats; stencilling with a stencil brush and very little paint; block printing; quilling; macramé; mosaic with grout; mandala dotting; Warli and other folk motifs. Test colours on scrap first, and use complementary colours for contrast or analogous colours for harmony.
Worked example
A tin-can planter: degrease, sand 120 grit, metal primer, two acrylic coats 30 minutes apart, dry 24 hours, then two varnish coats inside and out. Reasoning: enamel over rust fails, the primer gives adhesion on smooth tinplate, and varnish resists watering.
Traps
Painting over dust or oil; one heavy coat that runs and cracks; ignoring the inside and base; finishing in monsoon humidity; using glitter, which is a microplastic; decorating before the joint is tested.