Joint tape is a product which is used to finish drywall joints in preparation for painting. Putting up drywall is a relatively straightforward process, but preparing the joints for painting is actually a bit tricky, unless one doesn't mind a wall with a sloppy appearance. The process of smoothing out the joints so that they will become invisible after painting is known as taping, since it involves placing joint tape over the joints. This product is available from many hardware stores and home improvement stores.
There are two different kinds of joint tape available. The first is a paper tape product. To use paper joint tape, people apply a layer of drywall mud to the joint, smooth the tape down over it, and then add a light layer over the surface of the tape. The second layer of mud does not fully cover the tape, but it does help smooth it out. The tape and mud are allowed to completely dry before being sanded so that they are smooth. At the same time, mud will be used to address other cracks and holes which might show through after painting. This can be a painstaking process, but the alternative is an ugly paint job.
Mesh joint tape is self adhesive. It is applied to the wall as-is, and then covered in a light layer of joint mud, just as with paper joint tape. Once the mud has had a chance to dry, sanding can take place. Once the drywall has been prepared, it can be primed and painted. Taking the time to prepare drywall properly is important, because once paint starts to go on the wall, it is a lot harder to adjust for problems and errors. At the least, a fix can be messy, and at the worse, it can be impossible.
In addition to being used in new construction and room refinishing, joint tape is also used when holes in drywall need to be repaired, to smooth the edges of the patch used to replace the missing or damaged drywall. After the hole is repaired and taped, it can be painted. Matching the existing wall can be a challenge, so it may be necessary to paint the whole wall.
When working with joint mud, known more properly as joint compound, it is important to be aware that mud dries quickly. People usually mix small amounts at a time to avoid wastage, and they must constantly clean the knives used to apply it, so that joint compound does not dry on the blade. It helps to lay everything out and strategize before mixing a batch of joint compound, as once the compound is mixed, the clock starts ticking.