Sound Deadener Showdown
Version 2 Updated: October 25, 2005
Products Reviewed: B-Quiet Extreme and Ultimate, Brown Bread, Cascade Audio Engineering VB2, Dynamic Control Dynamat Original and Dynamat Xtreme, Elemental Designs eDead v1 and eDead v1SE, FatMat, RAAMaudio RAAMmat BXT, Second Skin Damplifier and Damplifier Pro,
Asphalt vs. Butyl - Which is Right for You?
Let's face it. Most of you are reading this because you are trying to decide which product to use. That's what started me down this road. Some features will be more or less important to you depending on how extensively you plan to pursue sound deadening - if you are only going to put a piece behind each speaker, price isn't going to be critical.
This is the second version of Sound Deadener Showdown. I made a lot of mistakes the first time through. My ultimate recommendations were valid, but many of my assumptions were false - mostly because I gave too much credence to the manufacturers' claims. In the months since the first version I have done a lot more testing and have had the benefit of a number of bona fide experts - engineers, chemists and even a disgruntled employee from a company that makes some of these products.
If a company claimed their product had a high heat tolerance, I believed it. If they claimed that their mat had a 1 mil pressure sensitive adhesive, why not? If they published ASTM E756 Acoustic Loss Factor results, who was I to question them?
The best product for you will be the one that balances your requirements for performance and value. Performance can be judged in two basic ways. We've already determined that vibration damping is accomplished by adding mass and through the viscoelastic property of the adhesive/damping layer. If the product stays where you put it, mass is mass and both performance and value can be compared by looking at pounds per square foot.
The viscoelastic function is harder to quantify. All of these products perform at their best at a particular temperature - the point where the adhesive/damping layer's viscosity is most efficient. This is usually close to room temperature.
What about Acoustic Loss Factor testing?
There is a standard testing methodology that would be very helpful to us. The ASTM E756 testing procedure is defined here. If we could compare test results for all of the products we are interested in, we would have an objective reference. Unfortunately we can't. The tests are more than a thousand dollars each, and unless someone wants to kick in for it, it won't be happening here.
Some manufacturers publish test results purported to be ASTM E756 compliant. I don't believe these published numbers are valid. If you look around for ASTM E756 test results for other product categories, you will immediately notice that each report is accompanied by a report from the testing lab describing the exact procedure followed, the name of the testing firm and individual performing the test, the date and a discussion of the results. This report serves as a certification of the results. None of the test results published by the companies covered by this review display any certification at all. If you want to review the numbers for yourself, check the Web sites for Dynamic Control (Dynamat), B-Quiet and FatMat. I would love to see evidence that the tests are valid, but I will not be holding my breath. My working theory is that Dynamic Control came up with numbers somehow - I have heard several possible explanations. B-Quiet and FatMat then took those numbers and created their own using the "what might be plausible" methodology.
The problem with having suspect test results out in the marketplace is that it eliminates the possibility that a competitor will sponsor compliant tests. Assuming that the suspect numbers are inflated, legitimate results would represent a competitive disadvantage, so we all lose. The best we can do is select products with the best stability over the widest temperature range.
What are these things made of?
This is at the heart of the matter. There are three basic compounds used for the adhesive layer of these products:
SBR(styrene-butadiene-rubber)/Asphalt
This is the least expensive material to use. It is predominantly asphalt with a latex polymer, the SBR part, added for stability. Asphalt has one virtue. It is cheap. They make roads out of it. Unfortunately, it has several negative features that limit its usefulness for our purposes. It melts at a relatively low temperature. It becomes brittle at a relatively high temperature. Both states are bad for us. Optimum viscoelasticity requires that the material not be liquid or solid. Basic mass loading requires that the material adhere to the surface we want it to. If it melts, it will fall off vertical or inverted surfaces. If it becomes brittle, it is susceptible to detaching under normal vibrations.
The rubber compound is added to the asphalt to stabilize it. SBR/asphalt melts at a higher temperature and becomes brittle at a lower temperature than plain or "neat" asphalt. This doesn't completely solve the problem. SBR is subject to long term deterioration at temperatures that are possible in a car.
When I started this investigation, one of my primary objectives was to figure out why so many people seemed to have trouble with their mat falling off. If you search the Web for sound deadener falling off, you will see lots of cases of asphalt mats failing and no failures that I have been able to find involving butyl based mats. It just isn't possible that user error would be so neatly divided.
I looked at the specifications for products developed for roofing, which many of the products in this category began life as, I saw the problem. Roofing materials are designed to withstand temperatures of 158°F for two weeks without melting. Manufacturers supply butyl products for situations that will either exceed this temperature or duration. Extend the time and the maximum sustainable temperature falls. This explains why some people have had success with asphalt mats for a few years, only to have them fail in a subsequent year. Failure can be disastrous. If you're lucky, the mat will just fall off. If you're not, it will melt - pools of asphalt in your carpet or upholstery or window mechanism.
Another problem with asphalt mats is the smell. You should be fine during cool weather, but on a hot day, they tend to smell like, well asphalt.
Peel & Seal and Jiffy Seal are roofing products that fit in this category. Many people buy them for sound deadening. Of the products I tested, B-Quiet Extreme, Brown Bread, Dynamat Original, eDead v1, eDead v1SE and FatMat are in this group. Many people report great success with one or more of these mats. They are certainly the cheapest option. If you know your car will never be exposed to extreme heat or cold, they may work for you. I'm not suggesting that all of these products have a 100% failure rate under extreme conditions, but I do believe they are risky. Their narrower temperature range also means they will be less effective the farther they get from room temperature. I would not use any of these products in my car.
Butyl with Asphalt filler
I tested two products in this category - B-Quiet Ultimate and RAAMmat BXT. The adhesive layer is butyl for greater temperature resistance and odor control than the SBR/Asphalt mats. Asphalt is added to the butyl to add mass because it is inexpensive. This reduces the beneficial aspects of butyl to some extent, but they are demonstrably superior to the SBR/Asphalt products. They melt at a substantially higher temperature and stay flexible to a lower temperature.
The asphalt content makes these mats less expensive than the products in the next category. If you want to save money and still get a product that will be reliable, this is the category to pick. Please don't confuse products in this category with the asphalt mats described above. If there were only two categories, these mats would be grouped with the next. They have none of the problems associated with the SBR/Asphalt mats. The asphalt is suspended in a nearly inert state and only serves to add mass and control costs.
Butyl with a non-asphalt filler.
Products in this category match a butyl base with a non-asphalt filler to add mass. The mats I tested have a higher butyl content than the butyl with asphalt mats and are therefore more expensive. Second Skin Damplifier, Damplifier Pro and Dynamat Xtreme fall into this group. I'm also looking forward to samples being sent by Cascade that have similar properties.
These are the elite sound deadeners. They have the heaviest aluminum foil constraining layers and are the most expensive to manufacture. They have heat tolerances significantly higher than any of the other products I tested, with the Second Skin products having the highest tolerance of all. If your mat is going to be exposed to extreme conditions or if you are willing to pay more to squeeze that last bit of performance out of your efforts, these are the mats for you.
I know some of you don't believe me
FatMat is identical to Dynamat Xtreme.
No it isn't. Please stop saying that.
I did the search above and I found reports of both RAAMmat and Damplifier failing.
That is correct. Several years ago, RAAMmat and Damplifier were asphalt based mats. Both companies chose to upgrade their products - RAAMmat to a value oriented Butyl with asphalt composite and Second Skin to an ultra premium high butyl content mat. Both companies have gone to great lengths to replace the asphalt mats that failed.
Consider this. Price competition is fierce in this product category. Butyl content is more expensive than asphalt, squeezing the margins for both companies. Why would they do this other than to provide a better product? If asphalt mats were "good enough" why would they have bothered upgrading their products at all?
I heard that eDead and FatMat were really Peel & Seal.
I've heard that too. I have seen samples of Peel & Seal that are indistinguishable from the products you mentioned.
Why would those companies sell roofing products for automotive use?
I never said they did. I just said I heard that.