Modeling clay to damp Heresy horns -- how much?

[GWK]

I've bought a bunch of oil-based non-hardening modeling clay and stuck it to the horns and woofer basket in one of my new Klipsch Heresies. I'm pleased to report that it's audibly smoother than the undamped speaker as a result.

I put 1/4 to 1/2" of clay on all of these surfaces (covering basically all of the woofer basket and horns, with more clay toward the throat of the mid horn.) I used about 3lbs of clay on the one speaker done so far. However, since I bought the clay before I even had the speakers, it turns out that I have WAY more of it than I'm likely to need (I bought 20 lbs, for less than $30 shipped it's a decent price, I think).

Here's my question, for those who have used clay or a similar damping compound on your speakers: Is there any benefit to having more than 1/4 - 1/2 inch on the metal driver surfaces? That seemed like a lot while I was doing it (and my hands, wrists, and even elbows hurt the next day -- for the second speaker I think I'll warm the stuff up to soften it), and produced some results, but I wonder whether I've reached the point of diminishing returns yet. I have a lot of clay, and it's kind of fun to apply (I felt like Richard Dreyfuss in "Close Encounters"), so I'm open to using more.

I really like the way these sound, so I may proceed to irreversible modifications, like gluing in some additional cabinet bracing. I'll probably use the rest of the clay on the cabinet panels after bracing the heck out of it.

GWK