Different types of rubber bands and their uses for Dreadlocks. - Dreadlocks FAQ's
There are a couple different types of rubber bands that can assist your dreading. Each type has it's advantages and disadvantages and a good understanding of dread-rubber-band-ology will go a long way to helping you make good rubber band decisions.
Regular "rubber" Rubber Bands
These are the rubber bands that are currently included with the kit. These are almost always a very stylish black and they look and feel like regular rubber bands...just smaller.
These bands are great for the roots of your dreads. At the roots they are never worn tightly, instead they put gentle pressure on the base of the dread, gathering the hair together, but still giving it freedom to move. For info on using bands at the roots check out this post.
They can also be used at the tips of the dreads but I prefer the pro elastics mentioned below for tips. They tend to last better under pressure and they are thinner, so they are less noticeable.
The cool thing about these bands is that they often remove themselves. They pop off when its time, usually at around two months. This is because the rubber is soft and wearing them day to day eventually weakens them. Having them pop off is ideal because there is no painful snagging of hair involved. Occasionally you'll have to replace them if they are still needed on a particular dread but very often the dread will be ready for them to come off and this saves you some work.
It's important to note that long after the band begins to weaken the band will eventually begin to break down and get gummy. If you're not regularly maintaining your dreads it's possible that you wouldn't notice this and if the band was sufficiently tangled in the hair it could stay there until it broke down completely and got sticky. That would suck. So keep an eye on your bands and if you notice one getting soft, go ahead and remove it. It's really unlikely that this would ever be an issue since you will generally be done with the bands in less than three months and they usually take around five months to break down, but it's good to be aware of none the less. On that same note, getting rubber bands very hot with a hairdryer can cause them to wear out faster as well. At the roots you probably wouldn't get them that hot because your scalp is less than an inch away, but at the tips it could be an issue, so try not to cook your rubber bands.
Hair Elastics or Pro Elastics
The elastic bands last much longer than the rubber bands. They can last for ages without weakening at all. This was really important when bands needed to stay on the tips for a long time while we waited for the tips to lock. Now this process is a lot faster with the Loose Hair Tool method so the bands are not needed nearly as long. These bands are pretty cool because they last and last and they are very strong. They can hold the tip quite tightly as long as you need them to and they can also be used when combining dreadlocks, where they might be needed for a several months. They also seem to be much more heat resistant and they are easier to put on and remove without snagging the hair.
At the tips they are less visible than the standard rubber bands and they are also available in clear, which looks great if you have light colored hair rather than dark. For info on using rubber bands at the tips of your dreads check out this post. They can also be used at the roots but you will need to remove them manually when the time comes because they won't pop off by themselves. If you have a stubborn dread, maybe one that is right on top of a cowlick, and it never wants to lock on it's own... A great tip is to put one of these elastics on it and just leave it there. It will help the new growth lock an make maintaining the dread much easier. One band will hardly be noticeable either.
You can also put these bands at the roots of two dreads that you want to combine. It will help them start growing together and remind you no to rip them apart while your looking for dreads that need to be separated after a shower. After the dreads have been growing as one for an inch or two you can remove the band.
I've heard that wearing rubber bands will prevent your hair from dreading and cause weak spots in your dreads. While this might be the case if they are used improperly I can assure you that you won't have these issues if you use them when and how I've described. When people spread rumors and mis-info like that they tend to drop the context. (maybe because they don't know the context) They never say, for example, that "rubber bands create un-dreaded areas in your dreads if you put them on the loose hair at your roots very tight and leave them there for weeks." Which in fact is true. That's why I'm careful to give complete instructions. You'll find that the same people will have negative things to say about using dread wax and palm rolling and clockwise rubbing, and in each case they have managed to drop the context surrounding their inaccurate statements.