Guide to Wood Fillers and Repair Compounds
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Guide to Wood Fillers and Repair Compounds


When you have a repair job and are not sure what you need to buy to tackle this chore, what should you do?  The only thing you can do is hope there is some type of guide you can check and see what is recommended for the project you have in mind. With the many different types of wood fillers, compounds, spackles, and epoxies that are sold today, finding the right one may be a difficult task.  With the following help you should be able to find the exact product you require to undertake this project and repair it like a professional.

There are several types of fillers and the one recommended for your project or repair job must be the right type or it will not perform what it is intended to do.  Find the right one for your project by checking the following:
Spackles: Regular (Vinyl & Resin Based) / Lightweight
Regular bodied spackles are thick heavy weight compounds that can be used for various interior and exterior projects.  This type is used to fill holes, cracks and dents in wood, drywall, plaster and metal.  Vinyl Spackles are more flexible for difficult exterior applications.  Light weight spackles are perfect for nail holes and cracks in walls or the ceiling.

The best rule of thumb to remember when choosing the spackle you will need for your project is the smaller the hole or crack you are filling, the lighter the weight of spackle you will need.  If the hole is too big, spackle will not help.  There will have to be some type of support behind it to hold the spackle.
Wood Filler: Water Based / Solvent Based
Water based wood filler is used for the easy cleaning properties.  This type does not dry out easily in the container.  It adheres easily and the clean up is a snap. Water based filler can shrink when it dries.  It also sands easily when dry and the finish is quite professional looking.  This is great filler for getting your unfinished wood ready to stain.  For light repairs of woodwork and furniture, this type of filler cannot be beat.

Solvent based wood fillers have been used for many years with terrific results and is considered a heavy duty wood filler.  The benefits of using solvent based filler are particularly beneficial for wood projects.  They contain actual wood and dry with similar characteristics.  Can be sanded, drilled and stained.  Solvent based wood filler is a better choice for simulating woods original characteristics, plus is fast drying if the crack is deep.  Shrinkage is minimal when compared to water based wood fillers.

Another benefit of solvent based filler is if the item you are repairing is going to be used outdoors, the water based filler can be easily damaged by water and the freeze thaw cycle.  For example, if it is deck railing, over time freezing and thawing can cause problems when using water based filler.
Stainable Wood Pore Filler: Brush Grade / Knife Grade
Wood pore filler is designed to fill large pores or small surface cracks prior to finishing.  Typical uses are with open pore woods like oak and mahogany.  Some are thin and can be brushed on and some are thick pastes that requiring using a wide putty knife.  Both are easily sanded.  The brush grade will shrink when applied to large cracks.

Grain fillers are available in a wide range of colors to simulate your wood species. Both types are used to produce a remarkably smooth surface for finishing.
Colored Wood Putty
Colored wood putty comes in a variety of colors matching many popular stains.  You can match it to the furniture or wood.  Normally it comes in a small tub ready to use.  A little whiting can be worked into it to control stickiness.  This is great for using on small spots where it can be applied directly to nail holes, cracks and seams.  The wood putty does not need to be sanded and it can be used indoors or out.
Wood Hardeners: Brushable Liquid / Two Component Resin
Wood hardeners are available as a thin brushable liquid or two component systems for heavy duty repairs.

Single component wood filler is normally premixed and is used for renewing wood that has rotted.  It can be used indoors or out. The main usage is on window frames and posts and decorative columns but can be used on any wood item that has started to succumb to the elements and time.  It is available to spray or brush on the surface being treated.  When using this type of repair compound, it will penetrate throughout the wood being repaired and harden or glue it.  The typical hardener dries overnight and then can be filled for additional repair, primed, and painted.

The 2 component systems are normally used for items that require strong support. Wood columns that are used for support are one example.  This type of repair compound is stronger than wood and will not shrink or crack.  The compound is spread using a knife or injected into the rotted wood and has a drying time of 12 to 24 hours.  After it dries it can be sanded then practically anything you need to do such as nailing, screwing, drilling, molding, or painting.
Epoxy Wood Fillers: Two-part Epoxy
Two-part epoxy wood fillers are normally used for repairing moldings, wood windowsills, and door jambs.  This is a great product for permanent repairs.  It mixes up similar to cookie dough and you can mold it to the damaged structure like modeling clay.  When it hardens, you can practically do anything to it, such as sanding.  This is normally used for smaller repairs that would typically be expensive to replace.  The two part epoxy is too expensive to use on big projects that can be replaced cheaper than purchasing the epoxy.
Bondo: All Purpose Two-Part Putty
This is a mixture of ingredients that are blended with a hardener to repair wood, metal, masonry, drywall, tile, asphalt, and many other surfaces.  The hardener is quite toxic and if it comes into contact with the skin can burn so it should be used with the utmost caution.  There are two types of hardeners to choose from depending upon the use of the bondo.

Often used on smooth metal doors, it can be sanded and painted after it dries.  Bondo will adhere to metal, plastic, and acrylic surfaces without damaging the original surface.
Window Glazing: Glazing Compound / Latex Based Glazing Putty
Many people prefer the traditional glazing compound over the latex based type that is available in a tube.  The reasoning behind this is traditional glazing compound is an environmentally friendly low VOC product that has been manufactured for decades.

Glazing compound is a type that makes a water tight bond between the glass and wood and is made of non-drying oils, Linseed Oil.  It forms a sort of cushion that expands and contracts normally without pulling away from the glass.  This type may take up to two weeks before it can be primed with an oil based primer then painted.

The type of window glazing that comes in a tube looks a lot like caulking, but doesn’t shrink.  Typical dry time is 5-7 days with good weather.  It is a good alternative if you want to get your windows finished in the least amount of time.