I was recently pointed to the Lawson Horns website looking for some information in their print publications on trying mouthpieces and leadpipes, but those do not appear to be online at this time. But there is still some useful information to be found, including notes on the topics of lacquer and of freezing of instruments.
As to lacquer, many pros like unlacquered horns and at a high level a player can begin to notice the dampening effect that they note for some types of lacquer in the following quote.
Lacquers come in two primary varieties: natural and synthetic. With respect to an unlacquered horn, which we normally don’t recommend as it lacks any protection from oxidation; the natural or air- dried lacquers have little or no effect on the instruments playing qualities. However, the synthetics, usually urethane, shrink during baking somewhat and can be expected to dampen the instrument about 3-5%. They are, however; easier to apply, look better and last longer so they are usually recommended for student instruments. Natural lacquer, while not lasting nearly as long, will still provide some protection for a couple of years so it is more costly to maintain.
Freezing instruments was a bit of a fad not long ago that seems to have faded out to a point today. I remember talking to my father, a chemist, about this and he was a skeptic that the temperature differences between room temperature and the frozen temperature were enough to do much of anything if the instrument were dissembled and completely dry. I am sure there are believers out there [UPDATE: See the first comment, for example–I personally don’t have a strong position on this topic] but Lawsons tends toward the skeptical.
Freezing and other types of metal treatment have from time to time been promoted. Here again, the question,’ Does it work?’ , is not so easy to answer. We ran a study where a computer ‘played’ an instrument (ask for our article “Acoustic Primer” or consult Art Benade’s terrific text book, “Fundamentals of Musical Acoustics,” 1976, Oxford University Press, for how this is done and what the result’s mean), both before and after freezing with liquid nitrogen. It was clear that the amplitude of the fundamental mode of resonance of the mechanical, not airborne vibration, had increased, but actually decreased for the upper modes. So it can be expected that freezing influences the mechanical vibration of the instrument’s walls but does it have any musical significance? This is perhaps the most important question that must be answered. Even with all of our computer technology, a computer cannot tell you if something ‘sounds’ good. For a highly technical discussion of how we poll musicians and what musical attributes they seem to prefer, ask for our publication in the ‘Journal of the Acoustical Society’ on “Mouthpiece Correlations…”. We have found through extensive blind testing that they seem to prefer a musical instrument with strong resonance but even playing resistance throughout its range; i.e., no weak notes or ‘wolf’ notes. Freezing tended to increase the vibration below the lowest note played so any effects are possibly ‘felt’ by the musician through his hands but there were no measurable differences in the airborne vibrations. Additionally, a former representative of the Copper Development Assoc. has claimed that in recent tests the crystalline structure of brass alloys reverts back to its original state over a period of time after freezing.
There is more in the site and the list of publications available points to great resources worth requesting from Lawson Horns.
UPDATE 2017: The Lawson site is just a memory now, the links have been removed but glad to still have the quotes.