Mute on string instruments

Could someone tell me how this works - not the notation but the actual thing? I mean the mute on string instruments that softens the tone and would be indicated with Con Sordina etc (like in the beginning Roussel's pianotrio). I found some info on the internet that it is this foamy thing to be placed somewhere under the strings? How fast can you switch between Con and Senza? Does anyone has actual experience on how this sounds and are there any different (kind of) sounds that can be made by using it?

These are the two most common type of Mutes or strings,

That you put it in the bridge like this:

and the other type is very similar:

and also goes in the bridge:

The function is to add weight to the bridge and this makes it to vibrate less, the sound effect is less volumen and also a little different sound (let me see if I can get you an online recording of both timbres..

(I continue, just I can post only 5 pics per post, hold on.....)

The mute can be easily and fastly removed, (the 2nd type of mute can be left in the strings to be ready to use it again)

there is not in the bridge, just a little back where makes no muted effect, just takes a second to put it on the bridge again.

The 1st type is easy to remove too, just you place it somewhere else. I've heard the 2nd type detune the strings ? (any violin player used that one ?) the one I have is like the 1st type, and no problem at all.

The Mute works for all strings, just the size is different, this is one for Contrabass:

Here is one vid, she plays a little with and without mute, but maybe the effect is not very clear, let me found you one with a complete violins section

She's using the second type of mute

In this recording is the entire string section playing with mutes, you'll note and effect like the middle frequencies was reduced and the low and high are dominant.

There's actually a large number of mutes, you've only shown 3 of them. There are types that remain attached to the bridge and others that you just put on. While they are fast to put on, sometimes they have a tendency to detune the stringed instruments upon placement or removal. A lot of score give a short rest for the player to remove or put on the mute. Faster passages, especially.

Well, yes, I didn't mention this one:

:D

Thanks that made things clear for me!