Unit A3-13 Preparing Surfaces and Selecting Paints/Preservatives

Problem Area 3 Construction Systems

Lesson 13 Preparing Surfaces and Selecting Paints/Preservatives

Interest Approach  What has been done to the desk and shelve in the room? (Painted or stained)  Why is this done?  How do you prepare surfaces for painting or preservatives?

Student Learning Objectives  Explain how to plan the work and assemble the tools and supplies.  Explain how to prepare surfaces for painting.  Explain how to select paint and preservatives.

Terms  Alkyd-oil paint  Feathering  Flat finish  Gloss finish  Latex paint  Long-oil alkyd paint  Medium-oil alkyd paint  Mildew  Oil base paint  Semi-gloss finish  Short-oil alkyd paint  Stain blocker paint  TSP (trisodium phosphate)

Preparation Prior to painting  Before you brush, roll, or spray a drop of paint, there are certain preparations you should make to ensure a good job with a minimum of effort, errors, and splattering.  Start by gathering together all the tools and equipment you will need.

Preparation prior to painting  Paint scraper, wire brush, sandpaper, emery cloth, putty knife, hammer, caulking gun with caulking, glazing putty, spackling compound or drywall paste, and paint remover are some things you might need to prepare the surface for painting.

Preparation prior to painting  Assemble drop cloths, old newspapers, and masking tape to protect areas you do not want painted.

Surface Preparations Tools and Supplies TOOLS  Paint scraper  Wire brush  Putty knife  Plane  Glazing putty tool  Sander  Caulking gun  Hammer SUPPLIES  Sandpaper  Emery cloth  Steel wool  Wood filler  Glazing compound  Caulking  Glazing putty  Nails  Spackling compound  Drywall paste  Paint drop cloths  Paint remover

Preparing Surfaces  The finest paint, applied with the greatest skill, will not produce a satisfactory finish unless the surface has been properly prepared.

Preparing Surfaces  The goal is to provide a surface to which the paint can make a strong, permanent bond.  The surface must be clean, smooth, and free of loose particles such as dust and old paint.

Preparing Surfaces  Very little has to be done to new lumber  Previously painted wood needs to be cleaned and/or flaked wood need to be sanded  Fill all cracks, joints, crevices, and nail holes with wood putty, plastic wood, or caulking

Preparing Surfaces  Any stains should be removed.  Mildew is a black fungus-based stain that occurs in moist conditions.  Wash the area with household bleach or TSP diluted in warm water.

Preparing Surfaces  TSP (trisodium phosphate) is a heavy duty cleanser and is recommended that you wear rubber gloves and goggles when using TSP.  Stain blocker paint covers stained areas to prevent the stain from showing through the finish coat of paint.

Preparing Surfaces  When preparing to paint concrete, allow a minimum of 30 days for aging and drying to occur.

Preparing Surfaces  When preparing metal for painting, use solvent to remove any oil film.  Emery cloth, wire brushing, coarse sandpaper, or sandblasting can be used to remove rust.

Stages of Paint Deterioration  Dirty paint… wash with detergent and water  Chalked or powdered paint… wash with water and a stiff bristle brush  Checked and cracked paint… scrap or sand to a clean smooth surface  Crumbling and flaking paint… scrap and sand to a clean smooth surface

Stages of Paint Deterioration  Curling, blistering, and peeling paint … scrap to remove loose paint  … feather paint edges with sandpaper  … prime bare spots before applying finish coat  Stained paint … wash with a bleach or TSP warm water solution  … prime stained areas with stain blocker paint such as Kilz or Bin

Selecting Paint and Preservatives  Oil base paint is a solvent-based paint (used mainly as an exterior finish) that is cleaned up with turpentine, paint thinner, or a commercial brush cleaner.

Selecting paint and preservatives  Alkyd-oil paint is a combination of oil and alkyd resin resulting in a faster drying, harder, more durable paint surface.  Alkyd-oil paints may be short, medium,or long oil paints.

Selecting paint and preservatives  Short-oil alkyd paints, commonly used as appliance & automotive enamels, dry the most rapidly & form the hardest film.

Selecting paint and preservatives  Medium-oil alkyd paints are the paint sold as porch and floor enamel.

Selecting paint and preservatives  Long-oil alkyd paints are the high quality interior paints and exterior trim enamels that have great elasticity and exterior durability

Selecting paint and preservatives  Latex paints are water-based paints that are used as either an exterior or interior paint.  They are easy to apply, quick drying, have good color retention, are water thinned, and offer convenient clean up with soap & water.

Degrees of gloss and washability desired  Flat finish, sometimes called an eggshell finish, can be washed occasionally and dries with little gloss.

Degrees of gloss and washability desired  Semi-gloss finish produces a moderate gloss that withstands wear and washes well.  It is often used for walls and ceilings in kitchens, bathrooms, and laundry rooms.

Degrees of gloss and washability desired  Gloss finish is a high priced paint that is durable and washes well, but brings out all defects in the surface.  Gloss finish paints can provide an excellent coating if you are willing to spend extra time preparing a smooth, well-primed surface.

Review/Summary  What are some ways to prepare surfaces?  What are some stages of paint deterioration?  What are different types of paint that can be selected?