Timber boarding or plywood ceiling – clear finish is too dark

Causes

Old varnished or shellacked ceiling has darkened with age

Listed under: Interior, finishes, timber and wood-based, plywood, health and safety, chemicals, solvents, timber, ceilings

Cause

Old varnished or shellacked ceiling has darkened with age

Repair

  • Remove shellac as follows:
    • brush a section of the shellacked ceiling with denatured alcohol (ethanol or ethyl alcohol); leave to soak in for approximately 10 seconds
    • rub over the area with extra fine steel wool until the shellac has been removed from the area
    • when the whole ceiling has been treated, wipe over the ceiling again with a clean rag dipped in denatured alcohol
    • sand the timber and prepare for a new finish
    • wear rubber gloves and safety glasses when removing shellac
    • working on small areas at a time, brush paint thinner over the varnished area; leave for a few minutes
    • remove by scraping with a putty knife or rubbing with fine steel wool until the varnish has been removed from the area
    • if residual varnish remains, repeat the process
    • wipe over the ceiling with a damp rag when the varnish has been fully removed
    • sand the timber and prepare for a new finish
    • alternatively, use a proprietary paint stripper; apply according to the manufacturer’s instructions
    • work in a well-ventilated area and wear rubber gloves, safety goggles and a respirator when removing varnish.
  • Remove varnish as follows:
    • Methylene chloride (the active ingredient in paint strippers) has wax added to thicken it and reduce evaporation. When applying to a surface, spread over section and leave until full bubbling/blistering has occurred. By continuing to brush it over the area, the wax barrier breaks down causing more rapid evaporation of the methylene chloride. If practical, cover the area with waxed paper to slow the rate of evaporation

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