|4 Steps to painting the Exterior
||1 2 3 4
1 Preparation of the surfaces
You should always examine the surface that you are planning to paint. Is any of the old paint peeling and/or cracked? Is there any noticeable fungus, algae and dirt on any of the paint? Unless you address any of these issues, this will prevent you completing a successful job and reduce the amount of time between applications. Correct surface preparation is the key to a long-lasting paint job.
Correct surface preparation may take much longer than the actual application of paint so be sure to allow for this important step in your budget and schedule.
Remove old damaged paint
This is one of the most common and effective methods for many flat surfaces from smooth masonry and hardboard to wood and ferrous metal. For best results, always use a sharp edged scraper and apply even pressure as you scrape in one direction, then at 90 degrees. Use triangle or oval (combination) scrapers to get into corners and on rounded profiles. Take care not to use excessive pressure or the scraper may gouge or score the wood. For heavier scraping on hard or metal surfaces, there are heavy duty scrapers. Light sand all rough edges of remaining paint with a medium grade sandpaper to achieve a smooth finish. Safety wear (goggles / mask)should be used for eye protection, work gloves to protect the skin and limit dust intake with a protective mask or respirator.
A stiff metal hand brush works well on brick and other masonry. Wear goggles or face mask for eye protection, work gloves to protect the skin, and limit dust intake with a protective mask or respirator.
All areas that have been scraped should be sanded and made smooth with sanding. A power sanding tool like an electric belt sander would be suitable for wood and steel surfaces. The use of an electric sander is not recommended on masonry, hardboard, aluminium or plastic materials.
A high pressure washer is effective in lifting old, loose, flaking paint. The use of harsh cleansers or bleach should not be used since they can penetrate the substrates and inhibit paint performance. To prevent damage, spray at a horizontal or downward angle only using a sweeping motion. Power washing is not recommended for soft woods like cedar and redwood. Wear goggles and water repellent clothing and footwear.
Strong solvent-based removers work well on most solvent-based and water-based paints, primers, stains, and varnishes. If using any of these products, you should follow the manufacturer’s instructions very carefully. Follow all directions and safety precautions for use and storage of these products. Some products are highly flammable and should not be used near a naked flame or in extreme heat or unventilated areas.
This method can be very effective however great care must be taken for safety. Wear goggles or face mask for eye protection; use chemical resistant gloves, long sleeve shirt and trousers to protect the skin; and protect breathing with a respirator designed for use with heat gun paint removal. Do not use a blow torch, as they may pose serious fire hazards. Only use a heat gun designed specifically for paint removal. Do not remove old paint with a heat gun if you suspect it could contain lead. The heat can vaporise the lead and cause a health hazard.
Remove any fungus or algae
This can be stubborn to eliminate, but if it is not removed before priming, painting or staining, it can grow through (bleed) the new coating and ruin your paint or staining job. Fungal contamination thrives in warm, moist, low light environments whilist algae on the other hand proliferates in the presence of light. In addition to fungicidal washes; another effective method is to prepare a 3:1 mixture of water and household bleach. Apply the bleach to the affected area allowing a half metre outside margin. Allow it to dry for at least 20 minutes, reapplying as it dries. Rinse the area thoroughly with water and then wash it with a mild detergent and rinse again. Always wear goggles, rubber gloves and old clothes when working with bleach.
Clean the area
Before priming you should remove any dirt, chalk or treated fungus or algae. Clean the area thoroughly with detergent, water and a stiff bristle brush. Rinse the surface thoroughly with clean water, and allow to dry completely before priming. Another effective surface cleaning method is power washing with water. Never use harsh cleaners since they can penetrate the substrate and inhibit paint performance. If using bleach to remove the fungus or algae, be sure to wash the area thoroughly and allow to dry before applying paint. Wear goggles and water repellent clothing and footwear.
Prepare glossy surfaces
A new coating may not adhere well to a high-gloss surface, so it is recommended that all glossy areas be dulled (keyed) for the best primer or paint adhesion. Sanding with a medium grade sandpaper works well for general exterior work. After sanding, remove dust with a damp cloth. Chemical deglossers and specific primers are also available, but require care and caution. Leaving the product on the surface too long can soften and wrinkle the old coating. Follow all manufacturer's instructions and treat these products as strong solvents exercising safety precautions with protective goggles, gloves and clothing.
Select the primer
The primer coat is critical to a quality paint job and is primarily applied to any bare untreated surface. A primer should be used if the surface is very porous or is at all uneven in porosity; or if all chalk cannot be removed from the surface. It is also very effective even when used over sound painted surfaces to maximise adhesion of new coats and ensure an even sheen of a finish coat. Depending on the surface, a special stain-blocking primer may be required. Although both water-based and solvent-based primers are available for most applications, solvent-based primers usually provide superior stain-blocking. Keep in mind that primers have been developed specifically for different surfaces and it is vital that the proper primer be used for whatever supstrate is being painted. Be sure to read manufacturer recommendations about spread rates (how large an area can be covered per litre), drying time before a top coat can be applied, how long the primer can be left before it must be top coated, and how advisable it is to apply a second primer coat. These factors are important to ensure the best finish coat results.
Check all Sealant
Chances are if it's time to repaint, it may be time to re-seal too. Sealants seal areas where there are gaps in materials or where there were openings made in exterior walls for pipes, wires and light fixtures. You should inspect all sealant making sure that any cracked, loose or damaged sealant is removed by scraping it away. Apply fresh sealant to all cracks and openings again taking into account the manufacturers recommendations. Most sealants are suitable for exterior use, but should confirm when purchasing from a member of staff. Silicone sealants are durable and suited to exterior use but cannot be painted therefore acrylic sealant should be used for painted areas. For areas where building materials meet that are not going to be painted use a clear acrylic sealant for cosmetic purposes. Allow all sealant to dry overnight and re-apply as needed.
Check all windows for cracked or loose putty and replace with Linseed Oil putty. Remember to prime the timber window first so that the Linseed Oil is not absorbed into the timber causing the putty to crack. Use a quality water-based or solvent-based primer.
Next Page >>