Good way to dampen tonearm?

I am in the process of replacing the stock Klotz wiring harness in my Rega RB-900 with the single-piece "Incognito" wiring harness. I have been thinking about adding some damping material inside the tonearm tube, and considered trying a couple of shots of expanding insulation foam.

I'd appreciate comments about the wisdom (or lack thereof) of the foam treatment idea. I am concerned that the chemicals in the expanding foam might be bad for the dielectric on the very thin Litz wire inside the tonearm tube.

If anyone has any ideas, or personal experience, with ways to dampen arm tubes, I'd appreciate getting your commentary.
If you want to dampen your tonearm, I suggest water.
But I'm pretty certain you want to damp your tone arm. If you use the foam, it's permanent, you won't get it out. It will work and would certainly make an excellent dielectric.

I suggest instead you try compressing a piece or two of polyurethane foam and sticking it in the tube. Or possibly those soft orange ear plugs available at Home Depot for pennies, or maybe you have some at work.

Now dry off that tonearm and get going, PS, adding water to the spray foam will make it expand even more. I strongly suggest the tonearm be dry.

I think that is a very bad idea especially since this would be permanent. What if it sounded like crap? You would be buying a new arm.

DAP makes a foam that can be cleaned up with water, but the other stuff (Great Stuff?) is polyurethane based, it is very sticky, and you need something like acetone to clean up. It might attack the coating on your wire and will certainly expand out of the tube and make a mess that will be hard to clean up. You will also have to compensate for the extra weight.

While I assume it is a dielectric (insulator) it's dielectric properties will be different than the one it replaces (air) and may alter the sound.

You will also be changing the effective mass and resonant frequency of the tone arm and your cartridge may no longer be a good match for it. Check out

If you want to experiment I would go with the other ideas above that are easily reversed.

BTW dampen was used correctly in the original post.

v. damp·ened, damp·en·ing, damp·ens
1. To make damp.
2. To deaden, restrain, or depress:
3. To soundproof.

Dampen is a verb and was used correctly. Damp is a noun or adjective so it is used incorrectly in the phrase "damp your tone arm."
The real issue is your adding quite a bit of weight, especially with Water, you might not have enough counterweight, especially if your cartridge is a higher gram cartridge. Beyond that yeah permanancy of it is dangerous, and how would you really Seal water into a tonearm safely? I sure would not want it coming out on my equipment or record labels. By the way they make Tonearm damping Gel's of some type, and at least this would be a gel not hardend foam or runny water which you could still pull wiring and stuff thru I would guess, I think KAB turntables(?) somebody like that sells it.
There are a couple of inexpensive ways to dampen your tone arm that are easily reversable. One is to wrap the arm tube with plumbers teflon tape. Simply wrap the entire arm, or alternately, two or three spots with multiple layers of the tape. Another is to purchase some shrink tubes from Radio Shack. These are 4" long plastic tubes that can be slipped over the arm tube and shrunk snugly onto the armtube by gently heating them with a hair dryer. Either of these techniques will have a dampening effect and you can decide whether or not you like them. If not, simply remove them and you'll only be out a few dollars, at most.
Finally, Herbies Audio has HAL-O JR dampers that might work as well and if you don't like them just return them for a refund:
Why not dampen it with something from the outside instead of the inside? I remember a local audio dealer that did this with a Well Tempered table (not sure of the arm). He had it wrapped just as you would re-wrap a tennis grip. It was a rubbery material maybe 3 millimeters wide. I'm not sure what it was exactly, but this is certainly an idea to explore. Good luck!
I successfully dampened (wrapped)a tonearm using tiny foam wrap tape that was either from the dental or medical industry. Internally, the foam earplugs seem to be a good shot.
Oh yeah, I forgot to mention I experimented with various shrinkwrapping on the arm also. It is good as it is easily removed.
Some shrink tubing has glue on the inside that is activated by the heat. If you try that make sure you get the kind without glue. It would also be hard to cut off without scratching the arm.
So anyone hears improvement after damping the arms with Teflon tapes or shrink tubing? I know it varies with arm/cartridge, but want to get some statistic from experienced listeners.

It's common for speaker manufactures to damp their drivers, same goes for circuit designers in amplification. Why don't we see more arm tubes with damping materials coming from factories? I have owned SME, Graham, and VPI, none of them have damping on the arm tube. Is it because it's not critical and job of arm tube is to hang the cartridge in place while it reads off the LP? Otherwise, I will expect someone to build an arm from wood or some carbon matrix.

Someone please enlightens me.
ACTUALLY..."damp" and "dampen" are BOTH verbs and can BOTH be used to describe the deadening of a tonearm. Isn't English a wonderfully simple language?

FWIW...I've had decent luck with plain shrink wrap tubing on tonearms. Very easily removed.
Marigo VTS tuning dots are one possibility, also has a tonearm wrap,perhaps what Vanderstephan is talking about.
Ralph Karsten at Atma-Sphere ( sells a high quality tone arm wrap that may interest you. Check it out, Ralph can give you more information. Happy Listening
I have used tape that given to me last year. Not sure if it is Teflon or something else, but i ran the tape from the 'headshell' to just above where the bearing housing is and it made an improvement.

Things became clearer, it cured a bit of tenseness. Detail stood out clearer, transients were sharper.

there is also a suggestion of inserting a strip of balsa into the tube. you have to be carefull not to foul the tonearm cables so that anti-skate is not affected or flat out breaking the cable. The balsa should be just a bit wider that the interal tube so that it firmly presses against the walls of the tonearm tube. I expect this will do even more to dampen vibration.
Semi, follow the link in my post above and it discusses the resonance inherent in everything and why it is important to have the resonance of the cartridge/arm combo at the proper frequency.

There are arms made of wood and carbon fiber BTW.

I guess I need a new dictionary too.
A small collar of dynamat extreme (a car damping material)
inproved my rega tonearm. In fact I used at a number of locations on my old turntable which tought me how substantial and corrupting is all the radiating and extranous energy going everywhere in a turntable.
Tuff job getting rid of it all...
Why are you even thinking of adding dampening material to the tonearm? Does it noticeably ring when you tap it? I've read good things about the wire upgrade, but I would otherwise leave the arm alone.
try to find an old Stereophile 'analog survival kit' tonearm damping wrap
Taken from the web

"conservation of energy = Within some problem domain, the amount of energy remains constant and energy is neither created nor destroyed. Energy can be converted from one form to another (potential energy can be converted to kinetic energy) but the total energy within the domain remains fixed. "

all the energy from bearing chatter ,the spindle bearing friction, the stylus dragging through the grove etc has to go some where, my own intution (thats as good as it gets for me)suggest this is easily conducted throughout the turntable and into the tonearm etc, a further guess of mine is that some of the materials contemplated (foam for example)dont really get rid of it but are only to varing degrees conductors of this unwanted energy