Waterproofing New Plaster Without Waiting for Full Cure: Coral Proteção Sol & Chuva Antisaltpeter Action
Coral Proteção Sol & Chuva Pintura Impermeabilizante blocks saltpeter and can go on dry new plaster, without waiting for full cure or applying a primer.
Painting a new plaster wall usually means waiting: the saltpeter that migrates from curing plaster can stain and peel the paint. Pintura Impermeabilizante (waterproofing paint) from the Coral Proteção Sol & Chuva line was formulated for this specific case, with an antisaltpeter action that changes the traditional preparation sequence.
What the data sheet documents about new plaster
According to the technical bulletin, the product is formulated to be applied directly on new walls or plaster, because it blocks the appearance of saltpeter. This allows the painting to be done once the surface is dry, without having to wait for the full cure time of the plaster and without applying a primer in this case. The condition is that the surface is dry at the moment of application. It is a valid advantage for new plaster; other situations, such as weak plaster, loose parts, freshly applied textures or cracks, still call for specific preparation. Where the acrylic waterproofing paint fits among the other options is set out in the guide on types of wall and facade waterproofing and when to use an acrylic waterproofing paint.
How the film protects the wall
Pintura Impermeabilizante uses Power Flex technology, which forms a rubberised, flexible and water-repellent film. This film prevents cracks and infiltration, fights algae and mould and keeps walls clean for longer. The bulletin records that the anti-mould protection has the purpose of preserving the durability and the aesthetic properties of the dry paint. The product is classified by standard ABNT NBR 13321 as an acrylic waterproofer for walls and facades, focused on the protection and decoration of external environments. When the external wall already carries moisture, what the film solves and what requires fixing the cause is covered in the guide on acrylic waterproofing for exterior walls with moisture.
Thinning, coats and coverage
Thinning is 10%: ten parts of product to one part of potable water, mixing the product with a spatula before thinning. Three coats are applied, with a low-pile wool roller, brush or paintbrush. Drying is 30 minutes to the touch, 4 hours between coats and 24 hours for final drying. Finished coverage runs from up to 17 m² in the 3.6 L pack to up to 85 m² in the 18 L can and up to 94 m² in the 20 L bucket, and may vary with the type and condition of the surface and the colour.
Application conditions
The bulletin advises avoiding application on rainy days, with temperatures below 10 ºC or above 40 ºC and relative humidity above 85%. When the wall already has old paint, mould or cracks, the correct preparation comes before waterproofing. For the full range of this line and its criteria, see the Coral Proteção Sol & Chuva waterproof exterior paint guide.
Frequently asked questions
Can new plaster be painted without waiting for the full cure?
Yes. The product is formulated for direct application on dry new plaster, blocking the appearance of saltpeter, without having to wait for the full cure time of the plaster and without a primer in this case. The surface must be dry at the moment of application.
Is a primer needed on new plaster?
In this case no primer is needed, provided the plaster is new and dry. Weak plaster, loose parts, freshly applied textures or cracks still call for specific preparation.
How many coats and how much thinning?
Three coats, with thinning at 10% (ten parts of product to one part of potable water), applied with a low-pile wool roller, brush or paintbrush.
What does the antisaltpeter action do?
It blocks the appearance of the saltpeter that migrates from curing plaster, which can otherwise stain and peel the paint.