In this section you will learn how to prepare both new and already painted surfaces so that your new paint will perform to its stated specifications.
 Unprepared surfaces are the primary cause for premature peeling, for example.

As a free service to you, this page of the Home-Beautiful web site gives you valuable, detailed information about what you need to do before applying the paint. Both new and old surfaces require preparation. Get all you need to know about treating mildew, priming, sanding, washing, stripping, filling cracks and nail holes, right here.

ALL ABOUT SURFACE PREPARATION:

A successful paint job requires advance preparation of the surface to be painted. Most of us want to begin slapping on paint as soon as we bring it home but that would be a case of paint in haste makes waste. Okay, you might say you understand that previously painted surfaces might require some preparation, but surely new construction wouldn’t. Actually, both new and old surfaces require prepping. This can mean treating mildew, priming, sanding, washing, stripping, or filling cracks and nail holes.

In this section you’ll learn how to prepare both new and already painted surfaces. The three main reasons paint fails are; improper preparation, high moisture and the use of the wrong products.

PREPARING NEW CONSTRUCTION: New construction surfaces basically are either wood, masonry, concrete, or stucco. Each surface has its own requirements.

WOOD: All wood surfaces must be dry, and free of grease, oil, and mildew. Rough surfaces must be sanded smooth. Nail holes and cracks should be puttied and doors, windows, trim and joints should be caulked after the surfaces have been primed. Cedar and redwood are the most common bleeding woods used in exterior construction today, and they MUST be primed to prevent and retard tannin sap from seeping through the finish coat.

Pressure-treated wood must be tested prior to painting to determine the proper penetration of the coating. Test by sprinkling the surfaces with water. If droplets remain on the surface, do not paint until the factory finish has weathered enough to allow the paint to adhere properly. When water penetrates the surface, the surface has weathered sufficiently for painting. You can then prepare the surface as you would any other wood, by sanding and priming. New, planed clapboard siding must be sanded thoroughly to break the MILL GLAZE and to allow proper penetration and adhesion. Some wood washes will remove mill glaze as well.

MASONRY: All masonry surfaces must be thoroughly brushed with a stiff fiber brush to remove loose particles, especially on stucco and mortar surfaces. Cracks and joints must be filled by repointing (a method of replacing mortar between bricks), caulking, or other appropriate means.

If efflorescence is present on masonry, you will notice white crystals on the surface. When the water evaporates, white crystals are left. To remove efflorescence, first dampen the wall with water then scrub the surface with a 10 percent solution of muriatic acid or vinegar. Take proper precautions by wearing rubber gloves, boots, protective clothing, and protective eyewear. After treatment, flush the surface with clean water to remove all acid and allow it to dry thoroughly before painting.

Poured and pre-cast concrete must be allowed to cure for sixty to ninety days before painting. Block and stucco surfaces must be allowed to cure for thirty to sixty days prior to painting. A release agent may be present on concrete surfaces; if so, it must be removed. A release agent is a surface treatment used on concrete to release it from the mold, which it Is formed in. To test for a release agent, splash the concrete surface with water. If the water beads up, there is probably a release agent. Remove with a chemical cleaner that can be found at a paint store. Moisture content should be tested as well.

PREPARING PREVIOUSLY PAINTED SURFACES: First and foremost you will need to remove all blisters and any peeling and scaling paint down to a sound substrate. Do this by scraping, sanding, and wire brushing. Where wood is exposed, be sure to use a primer prior to applying the finish coat of paint. To prepare surfaces that exhibit chalking, clean them thoroughly by washing, power washing, or wire brushing and then applying primer. Remove and/or replace all loose or splitting caulking, putty, or glazing compound. Finish by priming.

Sanding glossy surfaces, especially those under eaves and protected areas that are not exposed to normal weathering is an important step. Crystalline deposits that develop on these areas are a major cause of peeling. They must be removed by flushing with a power washer.

REMOVING MILDEW: Mildew is the number one surface issue for most projects. It is common in high-humidity areas of the country but can grow and flourish in just about any climate. Its appearance may vary from gray or black spots scattered at random over a surface, to a uniform gray cast. Distinguishing mildew from dirt isn’t always easy and mildew may be harder to see on darker colors. Mildew must be removed because it can grow through a new coat of paint. To kill and remove it, use one of the many commercial mildew washes available in most paint stores. These washes have been specially formulated for this particular task. Remember safety first-always wears protective clothing and eyewear when working.

SANDING: The primary purpose of sanding is to remove rough edges, smooth the surface, and even out ridges between different paint levels, a process known as feathering. It cannot be overstated that wherever you have a sharp edge of old paint from cracking or scraping, it must be sanded smooth. If you don’t do this, the layer of the old paint will show; but, more importantly, the paint in this area will be thin and very susceptible to rapid failure. It also has much greater probability of peeling.

Sanding should not be used as a method for paint removal; however, light sanding must be done on shiny painted or metal surfaces to de-gloss the paint. The sanding roughens the surface creating a coarser surface having “tooth” so that the paint can “bite” and adhere better. Eliminating the sanding step in a paint project will greatly increase your risk of paint failure due to adhesion problems. DO NOT SAND surfaces containing lead or are suspected of containing lead. See the later section “ Lead Paint” for information on how to handle these surfaces. Devises for sanding are basically either human driven or machine driven. The former is best for small or detail areas: you can hold the sandpaper by hand or attach it to any number of devises that keep the paper secure. Other options include sanding sponges and blocks. These are easier to handle and will conform to various shapes. Mechanical sanding is a great timesaver on large, flat, minimally detailed areas. Use caution so that the tool does not gouge or leave round marks from disk sanders (grinders) particularly on softwoods like pine. Orbital sanders, the small hand held size with square pads, are very effective and easy to use.

WASHING A SURFACE BEFORE PAINTING: The success of your paint job depends on how well the new paint adheres to the old surface. Logic predicts that if there is a coat of dirt, grease, grime, or chalk between the two, the new paint will have difficulty adhering. It is imperative that the house be washed before painting. This is a really important step and should not be taken lightly because it will affect the overall outcome in terms of appearance and longevity. Paint cleaners are available at your dealer. Rinsing is important as well since some soap residue can prevent paint from adhering properly.

POWER WASHING: Power Washing is a fast and effective method of removing dirt, chalk, and mildew. It is especially useful when preparing large surfaces and when cleaning very dirty surfaces than contain stubborn contaminants such as grease, soot, and salt. It is RARELY a good idea to try to use a power washer to remove loose and flaking paint. Power washers can be purchased or rented from paint retailers, hardware stores, or equipment rental centers. The retailer usually provides operating instructions; however, there are some important instructions that always apply:

• NEVER use a power washer at high pressure. You can quickly cut the wood surface, leave gouges, open the grain and drive water deeply into the grain. Always power wash on the low setting. (500lbs or less)
• NEVER use a power washer as a tool to scrape away peeling or blistering paint. It is only for washing away dirt and other contaminants.
• On lap siding, make sure that water is sprayed in a horizontal or downward direction. Power washing at an upward angle can lift or dislodge the siding, or can force water behind it where the water can cause damage within the walls.
• Never use near windows, glass doors, lighting fixtures, or other possibly delicate exterior features. The force of the spray is strong enough to shatter glass.
• Keep the nozzle at the specified distance from the surface, usually in the 18” to 24” inch range. If the nozzle is too close it can damage the surface.
• FINALLY AND MOST IMPORTANTLY, NEVER POINT THE SPRAYER TOWARD ANY PERSON OR ANIMAL, INCLUDING YOURSELF. THE HIGH PRESSURE SPRAY CAN EASILY CUT INTO YOUR SKIN AND CAUSE SERIOUS INJURY OR DEATH.

• Lead-based paint must not migrate from the work site.
• All visible paint dust and chips must be removed from the site before the job is considered complete.
• No open flames, burning, or torching is permitted.
• No hydroblasting or power washing is permitted.
• No scrapping, sanding, grinding, or abrasive blasting without approved equipment is permitted.
• The local building department must be notified before the job begins.
• The owner must be made aware of the issue.
• Post signs “Lead Work in Progress” to notify people.

• Steps for minimizing exposure to lead when lead-containing paint may be present.
• Removal and in place management of lead-containing paint. For more information you may want to visit www. fiberlock.com.

• Dirt and other foreign materials such as tree sap, bird droppings, grease, etc;
• Fungal discoloration’s from mildew, mold, decay, and sap stain growth;
• Alge, moss, and lichen growth;
• Nail and other iron stains;
• Tannins and other extractives from the wood;
• Graying of the wood due to surface decomposition by sunlight and moisture, and;
• Fading/decomposition of weathered coatings;