The term “mastic” is widely used in the construction industry, especially by tile setters. Many electricians don’t realise that the gooey electrical tape they use to resist moisture is also a mastic. But this mastic rubber material is specially formulated for use as a dielectric insulator. Mastics from 3M are compatible with thermoplastic rubber wire insulation.
When you are working with odd shaped components or needing to tuck in some insulation where your tape won’t reach; mastic is the product to use. Think of it as putty on a roll.
Humidity? Moisture? Wrap it up!
In addition to low-voltage electrical insulation, mastic tape offers the best moisture resistance of any electrical tape made by 3M. They create a barricade around splices and terminations, so that they are resistant to contaminants and particles that can corrode your wire and connections. Mastic tapes are often used in outdoor applications because the rubber is ‘self-healing’, meaning that when it is punctured, the material will flow to fill in the void.
We recommend it for use within industrial environments where steam and aerosols are commonly present, and outdoor environments where connections need to resist humidity and moisture. For electrical connections that are continually submerged in liquids, 3M has other solutions like Electrical Resins.
Built for the odd shape and the long stretch.
Mastic tapes provide mega-stretch−up to 1000 times their original length. Sharp edges and bolted connections create potential puncture risks and failure modes for your splices which can result in costly downtime and repairs. With multiple configurations and thicknesses of moldable and stretchable rolls and putty, you can shape, smooth and pad just about any electrical connection. 3M mastic products provide plenty of options for insulating and weatherproofing odd shapes and complex configurations like:
Exceptionally pliable; it can be rolled into tubes or spheres or crafted into any shape to fill crevices left by tape splicing, especially on bifurcated cables. A mastic that’s used for this purpose is 3M™ Scotchfil™ Electrical Insulation Putty. Scotchfil putty is 3.2 mm / 125 mil thick and comes on a linered roll for easy transport and flexible sizing for your application.
There is another mastic application electricians may be surprised to learn about. Mastic tape can be used to deter pests. Ants create headaches for electricians by attacking pad mounted transformers, traffic control panels and ground level air conditioning units. *According to research done at Texas A&M University, the insects are attracted to the electrical fields, especially around relay switches. Power surges caused by these pests can cost thousands of dollars in electronics repairs or even human lives if those relays operate train switches.
Pests and rodents can cause havoc. Help reduce your regular maintenance costs with a simple mastic solution.
*Merchant, Mike. “Insects in the City: Fire ants shock homeowners.”
http://insectsinthecity.blogspot.com/2009/06/fire-ants-shock-homeowners.html (accessed September 15, 2017).
Jackets required. This tape can ooze.
Mastic is going to flow. So, for the better mechanical protection and to help prevent it from making a mess in your application; mastic should be completely overwrapped with another protective material like vinyl (PVC) or rubber tape. To make your job easier, 3M offers solutions for such applications.
There is a mastic for virtually every application.
Mastic comes in tape and roll form and in a variety of thicknesses and operating temperatures.
Even with a lot of information, understanding the pros and cons and picking a tape can be tricky. Let 3M save you time with these application summaries and quick product comparisons to find the right mastic solution for your application.
Choose mastic only when you need padding, flexibility and conformability to manipulate the material to fit on or in your application. At 3.2 mm / 125mil , they are your thickest options - but these tapes and putty are versatile and can be cut, stretched, scrunched and rolled to fit in even small spaces. However, you will still have to wrap another material like vinyl over it to contain the mastic and provide jacketing protection.
Choose rubber mastic for insulating, padding and resisting moisture in high voltage applications up to 35 kV. Rubber and mastic tapes dissipate heat and work up to 90°C with an overload temperature of 130°C .
Choose a cable jacket repair tape for preventative cable maintenance, and on-site repairs in rough environments like construction sites, steel mills, petrochemical plants and industrial manufacturing. They include flame-retardant mastic to keep moisture away and provide excellent adhesion to a variety of cable jacket materials.
You have a wide array of choices. This easy to read chart will give you performance ratings in a glance.
There are some basic rules to follow when you’re selecting electrical tape.
Get more information on product selection, applications and training in our Electrical Resource Center.