Lime-based plasters are mineral coatings that lack the flexible plasticizers of synthetic acrylic paints. When applied over improperly prepared substrates or under extreme environmental conditions, cracking, craze-lining, or delamination can occur.
1. Craze Cracking (Rapid Suction / Shrinkage)
Craze cracking appears as fine spiderweb lines across the plaster face immediately after application.
**Root Cause:** The underlying substrate absorbed moisture out of the wet lime plaster too rapidly, preventing proper hydration.**Prevention:** Apply a dedicated **Quartz Mineral Primer** to equalize substrate suction. Lightly mist porous basecoats with water before applying finish coats.2. Joint Telegraphing & Structural Cracking
Straight vertical or horizontal cracks following drywall seams indicate structural movement.
**Root Cause:** Expansion or contraction of underlying drywall studs or missing joint reinforcement.**Prevention:** Embed alkali-resistant **4.5 oz fiberglass mesh** across all seams and corner beads into the first coat of base plaster.3. Delamination (Flaking / Peeling)
Delamination occurs when plaster layers fail to bond mechanically or chemically.
**Root Cause:** Applying topcoats over oily, unprimed, or dusty surfaces, or allowing basecoats to dry too smooth without mechanical keying.**Prevention:** Ensure basecoats retain slight tooth/texture (like Marmorino Coarse) before troweling smooth topcoats.4. Efflorescence (White Salt Deposits)
Efflorescence manifests as powdery white salt deposits pushing through the plaster face.
**Root Cause:** Water migrating through porous brick or masonry, carrying soluble salts to the surface.**Prevention:** Waterproof external masonry walls and eliminate ground moisture leaks prior to plastering.