You should prepare and repaint the entire window unit. Begin by removing all loose paint with a wire brush or scraper. Don't forget the ends and underside of the sill, as peeling or cracking often begins there. Next, remove any old caulking from the joints in the frame and the areas where the frame meets the sill and where the frame and sill meet the siding. Finish the surface prep by sanding the wood until it has a bright, new look. This removes any decayed wood fibers from the surface and provides a sound surface to paint. Now apply one coat of A-100 Exterior Alkyd Wood Primer, again paying special attention to the end grain and underside of the sill. After the primer dries, apply an acrylic latex caulk to the joints in the frame, the space between the frame and sill, and the space between the window and the siding. Follow with two coats of a top-quality acrylic latex satin or gloss house paint, like SuperPaint. After you replace the storm window, make sure the drain holes at the bottom are open. This will prevent the condensation that builds up on the inside of the window from collecting on the sill
No. Paints can be formulated to inhibit mildew growth, but under some conditions, mildew eventually will reappear on any type of paint.
The eaves of a house are a frequent location for paint problems, with peeling topping the list of concerns. Moisture drawn out of the house sometimes is the source of the problem, but more times than not the culprit is lack of inter-coat adhesion. This occurs when paints are applied to old, hard and glossy paint films and when dirt and contaminants, such as salt, is not properly removed prior to painting.
Ultra-violet radiation from the sun causes wood to naturally darken. For wood surfaces that have never been coated, or which have been finished with clear varnishes or lightly pigmented stains, this darkening can be unattractive.
When paint is applied in excess of the recommended wet film thickness or when two coats of paint are applied too quick. This will not allow sufficient drying and wrinkling may occur. This surface imperfection should be corrected once the paint film has dried by power sanding. The smooth area should then be primed with a quality oil or latex primer prior to topcoating.
When dew forms on latex paints before the film has fully cured, a concentrated residue from the paint material can form on the surface, causing staining, unsightly runs and gloss patterns. This finish problem is known as surfactant leaching. Aluminum siding is particularly prone to surfactant leaching because this type of substrate reacts to temperature changes faster than wood. To avoid this problem, apply paint during temperatures that allow proper curing. Avoid painting during hot and humid days with significantly cooler evening temperatures.
Stucco and mortar joints contain hydrated or "hot" lime, a dry compound added to improve the workability of these materials. If the high alkalinity of mortar, cement mixes and concrete is not addressed prior to painting, a reaction can occur when moisture is present, resulting in blistering, peeling and burning stains.
The culprit here is a water-soluble dye called tannin. Moisture in the wood will cause the tannin to migrate to the surface and stain the paint. New red-colored wood must be sealed with a quality alkyd or latex undercoater to create a barrier between the topcoat and the wood. More severe cases of tannin bleed may need one or two coats of an alkyd primer to prevent discoloration.
Latex paints contain chemicals called plasticizers that allow proper film formation and keep the coating flexible. Many vinyl and plastic weather-stripping materials also contain plasticizers to give them flexibility. When two surfaces containing plasticizers come in contact with each other, they can have the tendency to stick. This condition, known as blocking, will generally occur during the early curing time of the coating, but it can continue for some time. Blocking can also occur on double-hung windows and garage doors. The easiest way to prevent blocking is to use a non-blocking acrylic, or alkyd base paint in areas where it may occur.
The deposits, known as efflorescence, are caused by moisture in the masonry. The moisture dissolves salts in the masonry -- the mortar, block, concrete, etc. -- and is drawn to the surface by the heat of the sun. The water evaporates, leaving behind white deposits that must be removed before painting. After you find and fix the source of the moisture, remove the efflorescence with a wire brush and coat the surface with a masonry primer and topcoat.