Received a mail from Ben Bouman a while back regarding Tone improvment, I thought I share it,

I asked him had he any tips on Tone improvement............

Reply below from Ben.

Well, that's tricky question!!!

It's one of the most difficult things to create a fat tone..
Being able to play "resonant" is one of the key elements.
Resonant playing means good breathing techniques, tongueblock ,
handtechniques etc etc..

Tongueblock is something that every player should practice ..BUT...it
doesn't mean that you have to tongueblock all the time.
I mix pucker and tongueblock all the time like many, many players do.
But the practice helps you to develop muscles, muscle memory, improve the
coördination(hands, lips, fingers etc etc).
It takes some time but you'll get used to it.

Try to play a major scale from hole 4 to 7 (on an A harp)...
play every note slowly and on half volume with these sounds..
EEH-AAH -OOH--UUH ( like in "you" and OH ( like the O in horse)..sorry for
the pour explanation but english is not my native language!!

So, play the major scale up and down starting with the EEH sound , than the
AAH sound and so on..( 5 sec.per note) and listen careful to every change
in sound.
Try to feel which note/sound almost vibrates , that you can feel in your
fngers/hands,cheeks .the bones in your face..

next is doing this exercise with tongueblock...listen very careful if there
is no air escaping through the holes beside the one that you play.

Try to practice on "medium" volume, between 25 and 75 % of what you are
capable of.

Next step will be handtechnique...but first do these exercises for a few
days/weeks...

please feel free to ask any question you have...I'll be glad to answer them
if possible.
If needed I can send you short files with examples or even a video take.

one more thing,,,,, when you start a note , start with a soft attack, not
the Tee sound that is one with the tongue but more like a Kaa or a Haa

hope this helps a little

Here is a bad idea for improving tone. for wooden harps, if you soak them in whiskey it will swell the wood making it much more air tight and giving you a great rich tone.

now I said it's a bad idea, and with good reason. while it does give you a much better tone, it also shortens the life of your harp, as over time the wood tends to "un-swell" leaving small spaces between the plates and the comb, allowing air to escape. so unless your about to play a gig with a bran-new harp and you've got $30 to waist on a new one, your best off avoiding this trick.