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When Planning An Exterior Paint Job

Mildew is a black or brown fungus that can grow on, and disfigure exterior surfaces, including paint.  While it is not possible to guarantee a 100% mildew-free paint job, especially for a long period of time, there are some precautions that can help significantly in reducing or avoiding mildew growth on a paint job.  Take as many of these into account as you can ,when planning and doing an exterior paint job.

1. The Environment: while there isn’t much you can do about this, keep these points in mind when deciding how much you want to do with factors you can control:
   • Warm, most weather, and absence of freezing temperatures fosters mildew growth
   • Mildew in the area leads to mildew growth (wind-blown spores)
   • Protected areas are worst; sunlit areas grow mildew less
2. The Surface Being Painted:
   • Never paint over mildew, remove it first; apply water: household bleach, 3:1, (protect eyes, skin, breathing; wet down plants and/or cover them); leave the bleach solution on the surface for 20-30 minutes; re-apply if it dries; rinse thoroughly
   • Bare wood, and oil-based paint as the previous paint, are bad for mildew
   • Prime these surfaces with quality acrylic latex primer; this includes surfaces scraped down to bare wood or to old oil-based paint
3. The Paint Being Applied:
   • Latex is better than alkyd and oil-based paint
   • Satin formulas are generally more mildew resistant that flat paints
   • A top quality paint likely has more mildewcide than a lower grade (a mildewcide is an ingredient that resists mildew growth)
   • Dark colors dry out faster (dew, rain), so tend to support mildew less
   • Use mildew-resisting additive only if recommended by the paint manufacturer
4. Applying the Paint:
   • Two coats are better than one; a thick coat is better than a thin one
   • Avoid painting when breezy, especially if mildew is seen in the area
   • Paint applied with a sprayer can be better than brushed (brush marks can hold onto nutrients for mildew, and mildew can collect there)

Maintaining Interior Paint

With Proper Maintenance, Quality Interior Paint Can Have an Extended Service Life

A. Dealing with Dirt
Interior paint typically gets dirty in many situations: hand prints around switches and knobs; splashes in kitchen and bathrooms; marks on hallways and corridors; “soot” accumulating above electric lamps and other heat sources.  Removing dirt before it accumulates not only improves appearance; it reduces chance of it getting permanently embedded in the paint film.  While changing color is a good reason for painting, covering over dirty paint is generally not a necessarily good reason for repainting.

1. Check for dirt periodically; and assume it will be present in and near cooking areas (airborne cooking oil) and at all places at hand height.
2. Always initially clean the surface with a mild detergent with a sponge or soft cloth; resort to harsher cleaners only when necessary, recognizing that alkaline cleaners can dull the sheen or gloss of oil-based paint.  Abrasive cleaners will burnish nearly any paint, and will dull the gloss of satin, semigloss and gloss products.
3. Washed surfaces should be rinsed thoroughly because residual cleaner can interfere with adhesion of paint applied later.

B. Treating Mildew
Watch for growth of mildew on painted surfaces that tend to be most; this includes laundry and basement areas, bathrooms and kitchens.  Mildew should be treated and removed, and never simply painted over.

1. Apply a 3:1 mixture of water: household bleach to the mildewed area using a rag or sponge; wear eye and skin protection and a respirator; with colored paints, do a test area first to be sure the bleach solution with not cause fading; protect the floor and nearby articles.
2. Allow the mixture to remain on for 20 minutes; add more as it dries.
3. Rinse off the area thoroughly

C. Sticking
Sometimes painted surfaces will stick to each other, as with a door and the door jamb.  This is most likely of painted surfaces are put back into service before the paint has fully dried.  Dark color paints tend to stick more than do light colors or white paints, all else being equal; and glossier paints stick more than do flat paints.  Warm and damp conditions increase the tendency, and of course application of pressure increase sticking.

1. Allow ample time for drying before putting the painted area back into service.
2. If sticking is observed, rub talcum powder onto both surfaces to alleviate it. 
3. The plasticizer in gaskets in windows, doors, etc. can soften latex paint and cause sticking.  This is most problematic with new gaskets, and with dark-tinted paints.  It is best to avoid painting the gasket whenever possible.

Is there something you can put in the paint to help eliminate mildew?
A. Yes and no. There are additives for paint which are supposed to help with this problem. However, it usually requires more than a simple additive if the mildew is a re-occurring problem. Mildew grows in damp and shady areas with poor ventilation. Bathrooms will benefit from an open window and a ceiling fan. Other areas may just need frequent cleaning.