So on the chacha closed slaps are never used?
Well, I've seen some people play closed slaps on the chá. But it doesn't seem to be acknowledged batá technique. Most bataleros that I have seen, among them all of my teachers, play open slaps. But on a tambor, the last thing that people would check out is a drummers technique - as long as the proper sound is produced at the right moment. Ritual knowledge and repertoire are important, and ENERGY. I wouldn't blame someone for playing closed slaps, grabbing-hand slaps or whatever. But what is taught, technically, are open slaps, and that's what sounds and feels right to me. I find that closed slaps are even more cruel to the hands than "regular" open slaps on the chachá - which at times can make your hands bleed, anyway.
In matanzas style this can be done to the chacha of all 3 drums as well right? Like you mention here that is done on the iya enu
First of all, I think what you do on the chá and on the enú, respectively, is not to be confused or even compared. Secondly, I am definitely not that familiar with Matanzas style batá drumming; please refer to the DVD for that matter, or wait for someone else from this forum to speak up. But in Havana, the slap that is executed on the chachá covers a broader part of the head surface than the slap-like stroke that some people execute on the okónkolo enú to get that popping open tone from it. I find it hard to describe how it is done, especially because I got that effect out of the drum but once in my life, and I never play like that. What I did sometimes when I felt the okónkolo was not loud enough, was to play rim strokes on the enú. It isn't orthodox technique either; but it reaches the ear.
Thirdly, the special slap-like technique that can be used to achieve a muffled tone, is limited to the iyá, and it is not really a slap; it doesn't "slap" anyway. I just tried to describe the motion (technique-wise) that
can be used. Not everybody does it, though.
Why is this necessary?
Very simple: If you played a slap without dampening the enú on the opposite side of the drum, you would hear the enú resonating at the same time; as a result, the distinction between the two sounds wouldn't be that clear, making for dirty articulation. The slap sound from the chás that is required in ensemble playing has to be bright and percussive, without being cluttered up by an unwanted and misleading open tone share. You can check it out yourself - provided you don't have some of those thick hides on your batá that tend to be more forgiving than old-school thinner skins.
So when both heads are played its never done exactly at unison or does it vary?
This is no rule, just common practice. Nonetheless, there are drummers who are flamming all the time, others who do it occasionally, and finally some who don't do it as much. Maybe there are also drummers who never do it; I don't know.
I forgot to mention that the word "mordente" is taken from the classical music terminology, but does not refer to exactly the same thing. In classical music, a mordent describes an ornamentation comprising of three notes, while here only two notes are played. I know this as a "French flam". As a matter of fact, I have never heard it being called "mordente" before I got the Lenguaje DVD.
I hope that helps you a bit.
Thomas
P.S.: By the way, I avoided calling you Purity, or Sinner; how do you wish to be addressed, if at all (now that Thomas Newton is actually Richard)?