Scrub the entire mildewed area with a solution of one part bleach and three parts water – clean till all mildew is gone. Use rubber gloves and eye protection. Coo-Var Alkali Resisting Primer Sealer is ideal as a high quality primer prior to painting. It is resistant to solvents and salts, is excellent on walls and plaster with easy application, and is also ideal for use on walls and plaster.

Painting under direct sunlight or on surfaces that are too warm. This is especially true if the coating you’re using is dark in colour and solvent-based. For exterior masonry, surfaces can variously have a high pH level (alkaline), be chalky/powdery, or staining, which can cause adhesion problems and discolouration of the finish. While in most cases, if the surface is sound and dry, there is no need for a primer, but when you need one – use one.

Features

This primer improves paint durability and minimises the number of coats needed, significantly reducing costs. It is best suited for residential, hospitality, education, and healthcare walls.

Use the right painting techniques. Begin rolling at a corner near the ceiling and work downwards in sections of three square feet. Applying paint on a surface or coating which already has mildew or from which mildew has not been completely removed

Uneven paint drying – paint film dries faster on top if you paint when it’s either very hot, or cold and damp This can cause a headache for both walls and woodwork. If the previous colour was dark, this has can ‘grin’ through the new pale finish, meaning you may need an extra coat or two. This can be avoided by obliterating the dark shade using an undercoat on woodwork and a coat of a pale Matt wall paint on the walls. Of course, this also works if you are painting over a pale shard with a dark one, you just use a dark undercoat/matt instead. To find Ready Mixed colours, search "ready mixed" or select the Ready Mixed 'colour chart'. To see Tinted colours select a colour chart such as RAL, BS, NCS, etc. or search for a colour/hue to see available or related options. Remove sources of moisture. Repair loose caulk and install vents and exhaust fans wherever possible. High humidity or conditions where moisture seeps out of exterior walls. This is less likely to occur if you’re using a water-based paint as it allows water vapour to evaporate without reacting on the paint film.

Exposing water-based finishes to dew, high humidity or rain immediately after the paint has dried. This becomes a greater issue if the surface has not been properly prepared at first, or if the quality of paint is poor. As dictated by normal good painting practice. Care must be taken during application that the temperature is above the dew point to avoid any contamination. In confined spaces, provide adequate ventilation during application and drying. The easy answer would be “always”, particularly on bare surfaces, but of course it’s not that simple. Wrinkling is when a painted surface looks rough and crinkled, which usually occurs when uncured paint forms a skin. What are the possible causes?We have outlined the major benefits of priming (or undercoating), and when (and where) you may need to use a specific product. We’ve also given you a link to some of our tried and trusted “priming” products to help you make the right choice, and you can find our full range of “primers” here. When do I need a “primer” for internal walls/ceilings? Bare plaster that is fully dry may be “primed” with a thinned first coat of Vinyl matt(“Mist coat”). Filled sections should be dealt with in the same way (i.e. patch-primed). Bare plasterboard should be primed with Dulux Trade Drywall Primer Sealer. Painting Bare Wood Confirm that the problem is indeed mildew by applying a few drops of bleach. If it whitens, it is likely to be mildew.