Quick answer: Damp and problematic walls (mould-prone, friable plaster, chalking surfaces, old efflorescence) need a primer that bonds where standard primers can't grip. Rhinoluxe Bond and Key is the bonding agent for these jobs; followed by an appropriate plaster primer and a waterproof topcoat like Shield on the exterior side.
Fix the cause of the damp first — primer alone cannot fix structural moisture. Once the source is resolved, this is the prep system that gives you a paint job that lasts.
Diagnose before you prime
Damp comes from rising damp (ground moisture wicking up walls), lateral damp (driving rain on exterior walls), penetrating damp (cracks or roof failures), or condensation (interior humidity). Each needs a different remediation:
- Rising damp: install a damp-proof course or membrane below the affected wall
- Lateral / penetrating: seal the exterior with Shield or Megaflex on parapets
- Condensation: improve ventilation; paint won't fix it
Prep the problematic surface
- Remove all loose, flaking, or chalking paint. Scrape and sand back to sound substrate. If a chalking layer rubs off on your hand, it must come off.
- Treat mould with a fungicidal wash. Industrial degreaser or proprietary mould treatment. Let dry completely.
- Brush off efflorescence (white salt deposits). Stiff dry brush; don't wet it back into the substrate.
- Repair cracks. Crack filler appropriate to the substrate.
- Let the wall dry fully. Moisture content must be within the primer's spec — typically below 16%. Use a moisture meter on doubtful walls.
Apply the bonding primer
Bond and Key is engineered to bond to friable, chalky and difficult substrates that standard primers don't grip. It cures into the substrate and provides a stable base for the topcoat. Apply per TDS — don't over-thin.
On cement-rich or alkaline surfaces, use Solvent Based Plaster Primer first to neutralise alkalinity, then Bond and Key for bonding.
Topcoat with the right product
For interior walls in damp-prone rooms (bathrooms, kitchens), use a sheen enamel or sheen acrylic that resists moisture. For exterior walls facing lateral damp, use Rhinoluxe Shield — its elastic, waterproof film stops moisture from re-entering the wall.
What primer can't do
Primer cannot fix active rising damp, ongoing penetrating damp, or unresolved condensation. Paint and primer go down on a stable, dry substrate; if moisture continues to enter the wall from elsewhere, the paint film will fail regardless of which primer you used.
Need help?
Our technical team can advise on the right primer + topcoat system for your specific damp problem. Visit Rhinoluxe Table View or Edenvale, or call +27 84 985 6141. See the full primer range online.
