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.

TermsAlkyd-oil paintFeatheringFlat finishGloss finishLatex paintLong-oil alkyd

paintMedium-oil alkyd

paint

MildewOil base paintSemi-gloss finishShort-oil alkyd

paintStain blocker paintTSP (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 SurfacesTSP (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 SurfacesWhen 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 coatStained 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?