Rubber Mastic Tape

Proper wrapping
Shouldn't snap when you wrap.
Wrapping tape on a high voltage cable can be time consuming and error prone since the careful build-up of tape requires accurate half-lapping and constant tension in order to reduce build-in air voids. Rubber tapes are designed to stretch−some up to 1000%. Elongating the tape this way drives to compression, and that results in the strong self-fusion that provides great insulation and moisture protection.

In a typical tape splice, you'll tug and pull out the tape, stretching it to just before the breaking point. The tape's width narrows to about 1/3rd of its original size. The tape's length increases; your hand travels very quickly up to 20” away from where you started. Quite often you'll be wrapping in a tight location making this even more difficult. Proper taping techniques are critical to realizing the many performance benefits of rubber tape.

Backwinding rubber tape allows you to tuck the excess back onto the roll as you work, pacing out more as you make your half laps around the cable and helping prevent the tape from getting progressively further away from the work area.
Even pressure on the stretch helps eliminate voids and bulges, sometimes called ‘pregnant splices'.
A good rubber tape won't snap and break when you wrap.
Splices and terminations should always be jacketed with vinyl tape for protection from chemical contaminants and physical damage. Vinyl jackets help keep your cable from collecting debris.
Dielectric strength of rubber tape increases as you add layers. For low-voltage applications (<600V), always apply a minimum of 2½ half-lapped layers.

Moisture control
Self-bonding helps makes an air and watertight seal.
Rubber tapes repel moisture and are a great solution for outdoor applications or in manholes where water may occasionally seep in.
In production plants and manufacturing facilities where steam, dripping water and elevated humidity are present, self-fusing rubber tapes provide much needed moisture protection.
In a harsh environment, one that is subject to chemical and harsh fluid exposure; overwrap with a hearty vinyl tape to help prevent copper corrosion.

High temperature performance
Engineered to beat the heat.
Anyone who's left a roll of general purpose vinyl tape in the cab of their truck on a very hot summer day can attest to the fact that heat makes the adhesive soft. Extreme heat makes it ooze and flow.

Extra padding
Thicker for Padding. Designed to take the shake.
Engines and motors in a production line subject electrical connections to extreme vibrations. Rubber tapes are typically 4 times thicker than vinyl electrical tapes and provide extra mechanical protection for connections like motor leads that are subject to constant vibrations. They also provide excellent padding and conformability around surfaces with irregular, rough or sharp edges like bus bar and split bolt connections.

Understand each tape's properties. Read the manufacturer's specifications and recommended tips for tape storage. Some tapes are designed to stand up to high heat temperatures. Therefore it's adhesive will fare better in your truck over a long summer of 90°+ days than standard duct tape will.

Avoid exposure to direct sunlight. Do not leave your tape near the window where it can soak in UV rays for a prolonged period of time. Ultraviolet light can affect the chemistry of a tape's adhesive and cause it to become hard and brittle.

Be mindful of temperatures. Try to avoid both extreme heat and cold. High heat can melt a tape's adhesive and cause it to become a sticky mess. At the other extreme, if left in your truck amid freezing temperatures tape's adhesive may become too brittle to work. Ideally, tape should be stored in a cool, dry location. This isn't always possible to try to keep tape stored somewhere else other than your truck when outside temperatures get to extremes. If that is impossible, keep only the amount you will use in a day in the truck and keep restocking as needed.

Have a system for cycling your mastic tape. No matter how well you take care of your tape, you cannot maintain its reliability indefinitely. The best solution is to cycle your tape. Devise a labeling system so that you use the oldest tape first.

How to store rubber mastic tape
First, you should store tape somewhere away from the light, particularly windows. Ultraviolet light can even penetrate the packaging with time.
Then, you should store the tape in a cool place; the cooler the better, preferably 60°F/15°C or cooler.
Also, make sure to keep it dry. Even the presence of moisture in the air can contribute to a chemical reaction. Just take it out of storage a day or two before you need it to let it recover to room temperature.
You should also store your tape in such a way that you know when each lot was delivered so that you can use the oldest tape first.
Find out from your supplier what a safe height would be to stack the cases of tape and the skids on top of one another. Certain tapes can be crushed and badly damaged when the boxes are overloaded. Ideally, the storage should be on racks and take up just one skid.
Besides proper stacking and cool, dark, and dry storage, best tape storage practices dictate rotation of stock to yield the best value out of your adhesive tapes.