Patching and Repair
Before you tackle a painting project, odds are you'll have to patch up the surface you're about to paint. In some cases, repairs may be more than just a way to prep a surface for paint or stain -- they may be necessary to preserve structural integrity. There is a wide range of patching and repair products available for use on wood, drywall, metal and more. In most cases, patching up a hole or cracked surface is an easy task for any do-it-yourselfer. As you plan out your project, use the following questions to help guide you to a better understanding of the available materials and how to best utilize them:
• What types of repair compounds are available?
• What types of plaster products can be used for repairs?
• What general patch and repair substances are available?
• How can you best prepare surfaces for application?
• What tools will you need to get the job done?
Compounds, Plaster, General Use Products and Application
Prior to selecting which type of patch or repair product you want to use, you need to know a little bit about which types can be used on different surfaces. You'll also want to know how long they take to dry, what size holes and cracks they can be used to fill and how they are applied. Generally speaking, patch and repair products can be divided into three groups -- compounds, plaster products and general patch and repair substances. Understanding which type will work best on the job at hand will greatly improve the chances of achieving a high-quality repair, as will properly preparing the surface before applying any type of repair product.
Compounds: Compounds usually have the consistency of thick mud and are easy to apply. The period during which a compound remains workable is the time in which it can be shaped and manipulated before it hardens. Dry time refers to how long the substance takes to completely set. Spackling compounds are ideal for repairing hairline cracks and must be applied quickly and efficiently since they are typically only workable for a few minutes. Allow them between one and five hours to dry before applying paint. Glazing compounds provide a tough, durable seal between single pane glass and wood or metal window sashes. Stronger compounds tend to resist damage better but may be more difficult to sand after they dry.
• Wall and joint compounds are often referred to as "mud"
• Joint compound is inexpensive and may be used for both taping and texture
• Sand and clean surfaces thoroughly prior to applying joint compound
• Glazing compounds are ideal for use with wood or metal window sashes
Plaster: Plaster products are often available in powder form and are mixed with water to create a paste-like substance that can be applied to cracks and holes. Patching plaster is a substance that is used for interior plaster repairs and generally dries in a short period of time. Wet the surface of plaster walls prior to applying patching plaster to help it adhere better. Plaster of Paris is an easy-to-mix substance that works well for filling holes in interior plaster walls and ceilings. It can set very quickly, so avoid mixing too much material, as it will harden before you get a chance to use it. Plaster of Paris may be sanded after application to make painting easier.
• Patching plaster dries uniformly and can be painted over and textured to match the surrounding surface
• Plaster pencils can be used to repair small cracks or holes in plaster or wood
• Use cold water when mixing plaster of Paris
General Patching and Repair: Unlike compounds and plaster, general patch and repair substances are available in a number of different forms, including putty, epoxy, tape and patching. Putty is a versatile substance that provides strong adhesion and can be used to fill holes, cracks, joints and other defects in wood. Epoxy provides a strong bond and can be sanded and carved after it hardens. It is slightly more expensive than other repair substances and can be tricky to apply, but it offers tremendous durability, particularly when used to repair rotting wood. Wood must be completely dry prior to applying epoxy because moisture can interfere with the bonding process.
• Tape is used in conjunction with compound or plaster to repair drywall
• Putty can be used as both a filler and a glaze
• Putty that doesn't accept stains comes in multiple colors, so you can find a good match
• Make sure epoxy is specially designated for wood repair if using it for that purpose
|Glazing Compound||• Long lasting
• Resistant to moisture and extreme
• Remains semi-elastic under a firm,
|• Glazing single pane glass windows into
wood or metal sashes
|Joint Compound||• Available in powder or ready-mixed
• Available in quick-set formula
• Comes in bags, buckets, boxes or
|• Drywall construction or repair
• May be used for both taping and texture
|Patching Compound||• Ready mixed for easy use
• Expands and contracts with surface
it's applied to, helping to prevent
• May be used indoors or out
• May not be able to be sanded
|• Repairing cracks in wood, drywall, plaster,
concrete and masonry
|Spackling||• Designed for fast, efficient application
• Can be painted over within 1-5 hours
• Generally premixed
|• Repairing hairline cracks|
|Patching Plaster||• Sets quickly
• Comes as a powder that must be
mixed with water
• May be sanded
|• Repairing surface cracks and large holes in
plaster walls and ceilings
|Plaster Pencils||• Adheres solidly
• Dries quickly
|• Repairing fine cracks and small holes in
plaster or wood
|Plaster of Paris||• May set in a matter of minutes
• Can be sanded and painted
• Comes in the form of a white powder
that must be mixed with water
|• Setting bathroom wall fixtures
• Repairing plaster and drywall
• Casting, modeling or sculpting for hobby
GENERAL PATCHING AND REPAIR
|Epoxy||• Offers strong adhesion
• Usually white or metallic in color
• May be liquid or putty
• Comprised of a resin and hardene
|• Repairing auto bodies, appliances,
plumbing, rain gutters and garden tools
• Repairing and protecting wood
|Fiberglass Patching||• Provides continued flexibility after
|• Rain gutters, roofing, interior walls and
|Putty||• Available in dry or pliable form
• Available in multiple colors
• Some types may be stained, painted
• Difficult to sand
|• Repairing cracks, dents, breaks and holes
• May be used on furniture, wood, concrete
• Ideal for nail holes and cracks on
baseboards and window sills
Surface Preparation and Application: Prior to doing any sort of patching or repair work, you'll need to make sure that the surface of the area you're working on is clean and dry. Dust, dirt, grease, oil, stains and even paint may need to be removed, so be sure to consult the manufacturer's instructions before application. Air temperature is also important, as extreme temperatures can affect consistency and lengthen or shorten drying time. Drying times vary widely between substances, so make sure your repair is thoroughly dry prior to painting or staining. In most cases, patches and repairs can be accomplished with a fairly simple selection of tools. A putty knife is the most essential tool, as it can be used to fill holes and spread patching substances over cracks. Buckets and mixing tools may be needed for some plasters while sandpaper, wood rasps and files will help you achieve a smooth surface once you're finished.
• Quick-drying substances require you to work more quickly
• Joint compound can be mixed with either a masher or electric drill with a mud paddle
• Some repair substances can be shaped and applied with your fingers
• Always work in a well-ventilated area or use respirators and masks to protect your lungs
• "Wet" sanding reduces dust for a safer and more comfortable working environment
• Wear eye protection and gloves to protect against flying debris and burns and to prevent substances from
hardening on your skin
Tape: When repairing drywall, you'll need to use tape prior to applying joint compound. Paper tape requires a coat of joint compound to be applied first while self-adhesive fiberglass tape can be applied directly to the surface. To save time, use a banjo, which can apply tape and mud simultaneously.
Primer/Sealer: Some surfaces may need to be primed and sealed before being repaired. A good example of this is when working to glaze sash corners. Be sure to thoroughly read the manufacturer's instructions to ensure proper application and repair.
Sandpaper: If you're using a patch product that leaves a rough surface behind, sandpaper will be instrumental in smoothing out the surface to help it blend in with the surrounding area. Sanding is also necessary before painting in most cases, and scuff sanding in between coats of finish will often help subsequent coats adhere more readily.