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PREVENTING PROPERTY DAMAGE WHEN PRESSURE WASHING EXTERIOR WALLS

Pressure washing enhances the quality of any exterior paint job. However, special care should be taken to prevent property damage when pressure washing is performed. The ideal situation, especially when pressure washing a home, is to have the property owner present when the washing is done. Why? The homeowner can monitor the interior of the home and alert you to any problems with water entering the home. This commonly occurs around doors and windows. If the homeowner is not present, extensive damage to the interior of the home could occur.

CONSIDERING THE FACTORS THAT INFLUENCE TOUCH-UP

Touch–up is affected by a number of factors including:
• Temperature — Touching up at different temperatures versus that of the original paint application may result in color differences.
• Gloss — As a general rule, flat paints touch up better than paints with higher gloss. Also, latex paints touch up better than alkyds because there is much less change in gloss and color upon aging.
• Color — Dark colors are harder to touch up because they are more sensitive than light colors to minor variations in the porosity of the surface.
• Applicator — Touch-up is better when the touch-up is applied using the same method as that of the original application.
• Batch — Using the original batch for any future touch-up produces better results.

FACTORING IN TEMPERATURE WHEN APPLYING DRY FALL COATINGS

Temperature should always be considered when applying dry fall coatings. In low temperatures, the dry time is delayed and the overspray remains wet. Pulling equipment or walking on the overspray in these conditions can cause the paint to stick to the floor.

On the other hand, when using dry fall coatings in hot weather, the dry time is accelerated. In this case, care must be taken to ensure the paint applied lands wet on the surface being painted to ensure good adhesion. Dry fall coatings are extremely fast drying, and if the coating is partially dry when it hits the surface being painted, poor adhesion will result. A good practice is to hold the gun at the proper distance from the surface being painted, normally 12".

HOW DO YOU TELL IF A SURFACE WAS PAINTED WITH WATER-BASED OR OIL-BASED PAINT?

Knowing if a surface was painted with water-based or oil-based paint is important. Experienced painting professionals will tell you they can tell just by looking at a finish or touching it. They also use other ways to find out. If the paint is peeling, pull off a piece and bend it. If it cracks, it is most likely an oil-based paint. If it seems flexible, it is probably a water-based paint. Another way to check is to sand a small portion of the surface. If the paint easily sands into a fine powder, it is most likely an oil-based paint. Water-based paints have a tendency to resist sanding, and they gum up the sandpaper. If these methods fail, rub a small section of the surface with a cloth, wet with lacquer thinner. If it significantly softens, it is most likely a water-based paint. An oil-based paint will most likely not be affected by the solvent. Be sure to use appropriate safety practices when using lacquer thinner.

DETERMINING THE NUMBER OF PAINT COATS APPLIED TO A SURFACE

To determine the number of coats in a peeling paint chip, measure the thickness of the paint chip with a micrometer. Dividing the thickness by 1.5 (average film thickness per coat) will give a good indication of the number of coats.