Enter the wall area you're plastering plus type and layer thickness — get the exact kg, 25 kg bags and mixing water needed.
Gypsum ~1000 kg/m³, cement render ~1800 kg/m³, lime ~1300 kg/m³. Water ratio depends on product — check bag label.
Roughly 8–10 kg/m² per 5 mm of skim. A 25 kg bag covers ~2.5–3 m² at 5 mm. Add 10 % for waste.
Plaster is for smooth interior finishes, render is a coarser outdoor coat over masonry, and mortar bonds bricks or blocks together. Sand grade and mix ratio change accordingly.
Use 1:1:6 (cement : lime : sand) for standard exterior walls or 1:0.5:4.5 in exposed conditions per BS 5628. Never richer than 1:3 on soft bricks — you'll crack the face.
Only if the paint is fully bonded and you first coat it with a bonding primer such as PVA (1:5 with water) or SBR — otherwise the new plaster falls off within weeks.
Estimates only. Check the paint tin / adhesive bag for the exact coverage of your product.