How do you insulate electrical joints? Do you use colored tapes? Vinyl and plastic tapes are cheap and easier options. However, they are not as good as heat causes them to shrink. Major reasons are,
1. Tapes are pressure sensitive and adhesive based. They might not remain intact for long time for poor longevity of adhesive.
2. Vinyl and plastic tapes are not much resistant to chemical, abrasion and heat related wear and tear.
Heat shrink tubing is more secure due to chemical composition and mechanical reasons. They can offer close-fit even on irregular splicing. Also they are less messy to deal with. We'll see how heat shrink tubing works.
To start with you need right size of heat shrink tubing. Heat shrink tubes are available in different compression ratios. Though the most common compression ratio is 2:1, however, people do use heat shrinks tubes with 6:1 compression too. Standard guide to choose right heat shrink tube is - after-shrink diameter (recovered diameter) of tube must be lower than the area diameter you want to insulate or cover. Besides, expanded diameter (before compression) has to be large enough to fit on to the connectors and joints.
You have to cut heat shrink in right length. Once you heat, it shrinks lengthwise too up to 5 to 7%. So, always try to maintain a fraction of inch (1/4 inch approximately) extra on the both end.
Slip the cut heat shrink over the area you want to cover. In case you want to insulate an interwoven area of cables, maintain equal overlapping on both the sides for maximum protection.
Now, you need to heat the tube. You have to know the temperature at which the tubing shrinks. Generally, we use hot air guns for even heating. You can use iron solder too but never allow direct contact, as that will burn the shrink material. Manufacturers never allow use of open flame for shrinking purpose.
To achieve an even fit you need to start heat from any one end. That will clear out air bubble, if any, within the tubing. Slowly, move up or down to other end in rotation across the tubing for most effective fit. Maintain heating until you get a snug fit. Take care not to over heat. That'll char the tubing material.
Just reverse the process, and you'll get the heat shrink in expanded diameter for easy removal.