Review Details

2.5" Dia Sorbothane Hemisphere Rubber Bumper Non-Skid Feet with Adhesive

2.5" Dia Sorbothane Hemisphere Rubber Bumper Non-Skid Feet with Adhesive

Product Review (submitted on January 26, 2016):
Highly recommended with warm fuzzies!

The 50-durometer hardness rating of this product is halfway in firmness between the softer 30-durometer Sorbothane bumpers and the firmer 70-durometer Sorbothane bumpers. Sorbothane is a synthetic viscoelastic urethane polymer with excellent shock-absorbing and vibration-dampening properties.

These bumpers are great for putting underneath speakers or a subwoofer to attenuate the amount of bass frequencies that are transmitted from the speaker cabinet onto the floor. This is especially helpful if the speakers/subwoofer are located upstairs in a house or you live in an apartment or condo with downstairs neighbors. These will not totally remove the transmission of sound waves through the floor, especially if your stereo or home theater system is played at a very loud volume, but it will attenuate the vibrations being transmitted from the speakers' low frequencies by decoupling the speaker cabinet from the floor or shelf. These bumpers have a multitude of other vibration-dampening uses too. For example, if you place four of them under the corners of a turntable, they absorb vibrations better than the rubber feet that are used in most turntables.

The surface of these Sorbothane hemispheres feels sticky and tacky. These bumpers contain a plasticizer that can possibly leach and discolor wood. If you are placing these on wood flooring or furniture, you should insert a small piece of plastic wrap between these bumpers and the wood surface to both prevent the possibility of the plasticizer leaching onto the wood and to also prevent these tacky bumpers from sticking too tightly to the surface that they are sitting on. This is especially true for applications where you need to periodically lift these bumpers off a surface, such as if you need to sometimes move the speakers or subwoofer that are using these bumper feet. Leaving these bumpers pressed onto a surface for a long period of time can cause them to stick onto the surface like half-dried chewing gum. And even though each bumper has a backing of 3M adhesive, when you lift the object that is using these bumpers off of the floor, table, or shelf, the bumpers may be sticking so firmly to the surface that they can cause the bumpers' adhesive backing to pull away from the object that you originally stuck them onto. The tacky surface of these bumpers easily picks up dust, lint, and other debris, which can be an issue if a hard piece of debris is stuck onto the bottom of a bumper and it ends up scratching your wood furniture or floor. To solve this sticky issue, I thoroughly cleaned the entire surface of the bumpers and then wrapped the bottom of each bumper with a 1.5"x1.5" square of plastic wrap (cling film used to wrap food and food containers). The plastic wrap sticks very well to the bottom of these bumpers and they are no longer prone to sticking or leaching onto any surface without reducing the bumpers' vibration-dampening attributes. Some uses of these bumpers require that an object be firmly mounted to a surface without any possibility of shifting, and that object will rarely or never be moved (e.g. sensitive laboratory equipment mounted on metal shelves or Formica countertops). But for most applications such as using these underneath speakers, turntables, laptops, etc, I recommend wrapping these bumpers with a layer of plastic wrap if you do not require these bumpers to stick very firmly to the surface, and this will prevent the possibility of plasticizer leaching out, difficulty in lifting the bumpers from the surface, and debris sticking onto the tacky surface that may scratch wooden surfaces.

These Sorbothane bumpers are expensive, but they are a lot more effective at reducing vibration than generic stick-on rubber bumper feet. The Isolate-It! company does sell versions of these bumpers with a urethane coating that prevents plasticizer leaching and are also not as sticky. But at the present time, the urethane-coated bumpers are not being sold on Amazon and they are really expensive if you buy them directly from the manufacturer. Wrapping these bumpers in a layer of plastic wrap works just as well :)