Spackling compound is a material that typically is used for filling in cracks and imperfections on surfaces prior to painting or wallpapering. Gypsum plaster that is made of hydrated calcium sulfate and glue are its main components. It usually is available in two forms: a ready-to-use variety that is mixed to a consistency that generally is used for most repair work, and a powder to which water is added to make a thick paste. Powder form is often used as a joint compound so that it can be made thicker in order to cover butt joints on drywall.
The typical purpose of spackle is to create a surface that is smooth and flat so that it will not sag or have an indention when wallpaper or paint is applied on the wall. This is done by filling a hole, indentation, or crack with the compound and letting it dry completely. Many renters use spackling compound when vacating a unit to fill in tiny holes in the walls from nails, screws, or molly bolts that they used to hang pictures and mirrors. This procedure usually provides a quick, clean wall, helping the renter to get his security deposit back.
Spackling compound needs to be allowed to dry completely so that it does not crumble when paint or paper is applied on top of it. Some brands are colored so that it's easier to see the difference between when they are wet and when they are dry. This type is typically available in the ready-to-use form and is pink when wet, but turns white to let the user know it is time for the next step. This was created because some walls need a thicker application due to the depth of the crack, hole, or indentation, and requires a longer drying time.
Vinyl spackle is often used to cover imperfections in vinyl wall coverings. This step usually allows a homeowner to apply a second sheet of wallpaper or other wall covering directly on top of the original layer without having the time and cost associated with removal of the original. All types and forms of spackling compound usually should be sanded after they dry to ensure a smooth surface. This can be accomplished with a sheet of sandpaper on a sanding block for small areas, although a belt sander may be easier to use on large areas.