Follow our 3-step guide below on how to paint over exterior mildew with Zinsser products – with no bleed through.
Looking for help with how to treat interior mould and mildew? See our blog posts below.
- Treating Rising Damp
- Quick & Cost-Effective Ways To Paint Over Mould
- How to Spot the Early Signs of Damp
- What Causes Damp and Mould on Walls, and How to Fix It
Mildew on external surfaces is produced by trapped moisture in humid environments, usually by a build up of dirt. Keeping external areas clean and clear can help prevent it from forming but for areas blighted by mildew, specialist coatings for masonry, cladding, and hygienic areas – typically with good stain blocking properties – can be used to simply painted over.
A common problem with painting over areas blighted by mildew is bleed through the top coating; the solution is in Zinsser’s Allcoat Exterior. The finish is designed for long term protection, with 350 colours available in satin or gloss.
Zinsser listens to contactors and develops new products – or adds features to existing products – to meet their changing needs, delivering world class products that meet “real world” challenges, providing tried and tested solutions to painting problems, such as painting over mildew.
Step 1. Surface Preparation
Surfaces must be clean and dry and free from anything that will interfere or affect with the adhesion and application of the materials and Zinsser products to be applied.
Remove loose and failing materials by scraping or brushing with a stiff bristle brush to a sound edge, feathering the sound edges with a fine grade abrasive paper. Visible signs of organic growth should also be removed and the area treated with Zinsser Mould Killer & Remover to clear any contaminants on the surface, rinsing thoroughly with clean water to clean any remaining residues.
Allow the surface to dry and then fill surface defects and any small cracks with an appropriate filler (in accordance with the manufacturer’s instructions), allowing it to dry before rubbing down with a fine grade abrasive paper and removing all dust.
Step 2. Priming
Zinsser Cover Stain should be used to prime all stained, bare and filled areas, in accordance with the manufacturer’s instructions, and allow a minimum drying time of two hours (in normal drying conditions) before decorating.
Step 3. Decoration
Now that the affected area has been prepared and suitably primed, decorate with two full coats of Zinsser AllCoat Exterior Satin/Gloss in accordance with the manufacturer’s instructions. Allow a minimum drying time of one hour between coats.