Vintage DD turntables. Are we living dangerously?

Nope.....
Doesn't add up. The Goldmund mat was about 3mm and close to the mechanical impedance of the record. Vibrations pass through relatively unimpeded and the aluminum (usually) platter would reflect them back to the record. The mat will only take you so far and is eclipsed by the Goldmund platters methacrylate + lead.

A copper or stainless mat will pass the vibrations through to the platter with less resistance, but is dissimilar from the record and is less efficient draining vibrations in the first place.

That is why lead is the material of choice under a mat that tries to match the record. Lead is much more efficient at slowing vibrations and less are reflected back. Given the thickness limitations of a mat it's somewhat of a turkey shoot.

Fleib, in the course of marketing capacitors designed to reduce self-propagated microphonics, one of my most interesting interviews was with a respected OEM of TOTL tube amps who had been winding bespoke coupling capacitors with lead foil. He maintained that owing to its superior damping property, lead sounded better than much better conductors like copper or silver.

Fleib - please explain what doesn't add up. If you read my post I referred to the Goldmund platter, not mat. There is no difference between your post and mine.

Here is an example of the vagaries of mats - my final Audio VTT1 has a 16kg aluminium platter designed to work with a 4.5kg copper mat & 1.8kg weight. My Platine Verdier has a 15kg aluminium platter. Both are solid cylinders in shape.

On the Final the original copper mat has never been bettered, yet on the Platine Verdier the copper mat sounds awful.
On the Verdier I use a Counterparts System Mat ( distributed by Sota in the 80's) that is methacrylate with an embedded layer of barium lead. This is much better on the Verdier than the Goldmund mat you refer to. Conversely the Compositions mat sounds awful on the Final.

I think we agree on the turkey shoot, but there is some science behind what we hear.

Dover,
I don't doubt your results. They are what they are. It's the explanation that doesn't add up. The Goldmund platter is designed to match the mechanical impedance of the record with the surface adjacent to it. A steel or copper surface directly underneath the record is a different approach.

I don't blame science or lack of, for the vagaries of platters/mats. A mat is designed to work with an existing platter. As your results indicate (VTT1 & Verdier) there are too many variables to call this science.
I assume the Counterparts mat is the one Sota called Supermat (80's). It's different from Goldmund mat. The plastic formula is softer and I believe the Goldmund mat has no layer of lead.
As the names indicate acrylic and methacrylate are closely related. Delrin is DuPont's trade name for acetal homopolymer and like copolymers, can be formulated for differing hardness. Most platters/mats are probably made from copolymers and their exact formulation was/is a trade secret. The Goldmund mat seemed slightly harder than their platters, but this perception could possibly be influenced by thickness.

What then is the goal with an aluminum platter, to dampen the platter or match the record impedance? Perhaps both?

Regards,

What are the measurable physical properties of lead that could support the contention that it is superior for a platter or whatever other use in audio, including making capacitors? Furthermore, what is one looking for in such properties? This consideration will only engender another bunch of subjective opinions; I am not saying lead is right or wrong. Nor am I saying that I prefer any other material to lead. But our arguments are circular, always leading back to the fact that we are trying to connect our subjective opinions to physical facts, and the physical facts can be used to support one's argument in almost any way one wants to use them. What is missing is an objective way of assessing platter performance that is truly meaningful, and then the capacity to vary the properties of the platter to see how they affect that objective parameter of excellence. Ain't gonna happen. Call me a nihilist.