Ah.. I see the misunderstanding.. Even though they dry very hard, they are still elastomeric.Hard to tell in some cases but even the hardest of elastmeric resins, is in fact elastomeric whether your or I can tell or not.
I am not suggesting than anyone buy one, or the other. The determining factor limited only by the installers preferred application method.
Well, than and the area of the car you want to put it on.
Most people would not reccomend using a foil backed mat on the underside of the car, whereas most elastomeric coatings will hold up just fine.
If I understand your logic, you say that you are not willing to compare a coating to a cld in person because:
1. you have used coatings before (15 years ago) and assume they have not changed
2. with out labaroatory test gear, the human ability to detect such differences would be negligable?
If that is the case, then it seems like testing in person would go one of two ways:
Either the comparison would be so close to tell that the user would not be able to determine a difference, in which case, MY statement of equal performance between the two type of materials stands (since most of use don't base our perception of noise reduction on the lab gear sitting next to us in the passenger seat.
Or, the difference would be so great that the obvious conclusion would be that one is better than the other, thus negating the requirement of the lab equipment all together.
One or the other, but in either case the issue is resolved.
I happen to have some Spectrum left over from the sale of the company if you want me to send it to you.
You can try it out, and get back to us with your findings.
Just PM me with a shipping address and I'll even pick up the freight!
ANT
Im sure there is some elastic properties to a cured spray-on deadener, the question is how much. Your comments here suggest that a more rigid product works better, yet you fail to address that this is in direct conflict with the idea of these products using their elastomeric properties to absorb/reflect sound waves. I agree, its obvious that using a stiffening technique is a much more efficient means of altering panel resonances than relying on the elatomeric process to transfer sound waves into heat, but my original reply that started this debate discussed mass loading, not stiffening. Ive recommended many times that people, instead of using mat or even a spray-on deadener to get their roof to stop flexing, use fiberglass instead. High stiffening factor, relatively low mass (less than either product we are discussing here). My point is I understand about the difference between raising a panel's rez freq, and lowering it. I was discussing one, you are discussing the other. I believe this is a large source of our confusion and many of our differences of opinion here.
"If I understand your logic, you say that you are not willing to compare a coating to a cld in person because:
1. you have used coatings before (15 years ago) and assume they have not changed
2. with out labaroatory test gear, the human ability to detect such differences would be negligable?"
You understand me incorrectly. I said I was using spray-ons 15 years ago, I did not say I haven't used one since and assume they are still the same. Not only did I not say that, I explained that I have used Spectrum (were you making it 15 years ago? no) and even refreshed your memory to the fact I have my own coating recipe. So again, you acting as if I need to go out and buy one of these products before I have the experience worthy of discussing them, is a hollow attack on your part.
Where did I say differences would be negligible? I said testing it, and making an accurate comparison, for the average guy is virtually impossible. Say you go out and buy a few gallons of Spectrum and coat your car with it. Awesome. But what does that tell you about what would be different if you had used mat instead? Or maybe you suggest we coat half our cars with spectrum, and the other half with damplifier? Even if you found someone willing to do that, how would this average joe then go about measuring the differences in noise levels, while isolating the results to one side or the other of his vehicle? That really only leaves the rich stay-at-home dad who owns two identical cars, and is so curious that he is willing to use one product on one vehicle, and the other on the other. And he'd obviously then own some fairly sophisticated measuring equipment to accurately detail the results. Right Anthony? Come on, you are smarter than this, and we've debated back and forth for too many years for you to be pulling this 'try it for yourself' routine on me.
"One or the other, but in either case the issue is resolved."
See comments above.
"I happen to have some Spectrum left over from the sale of the company if you want me to send it to you.
You can try it out, and get back to us with your findings.
Just PM me with a shipping address and I'll even pick up the freight!"
That is a very generous offer, and is but one of the reasons I can debate you on a topic, even disagree with you, but still respect you. Not just that you'd give me some spectrum, but that you will back up your opinions to such an extreme. But, I still have some spectrum here myself (well not here, in my storage unit a few towns over). I think I have a gallon. Thank you for the offer anyway.
Cheers.