Dried up Ferrofluid?


What causes ferrofluid to dry up?  Heat, usage, age?  Is there a usual shelf life, as in, do most 15-20 year old tweeters that originally used ferrofluid, need new ferrofluid?

How is it checked, where is it bought, is the replacement generally the same from tweeter to tweeter?

Thanks ahead of time for any info regarding this!  I figure that there are quite a few good speakers out there that are getting up there in age so this may be something I’ll want to learn to do!
b_limo
Thanks George, I believe Thiel does in fact have ferrofluid per Rob at Coherent Sound .

pops
Thanks George, I believe Thiel does in fact have ferrofluid per Rob at Coherent Sound .


This correlates now with what many older Thiel owners are now finding and starting threads saying their speakers are harsh and/or have no sparkle. Their tweeter have lost a couple of dB’s and hf extension, and are now working very non linearly.

And this happens over time so you don’t even realize the tweeter performance is slowly degrading, and you enjoy your music less and less blaming your own age, your amps, your source ect ect

When all you need to do for $10 and a little labor-love is to clean out and change that ferro fluid in the tweeter.

https://www.speakerrepairshop.nl/en/instructions/replace-ferrofluid-in-tweeter/c-36

Cheers George
Thank you!
I have a pair of Kef Reference 3-2 speakers...They have ferrofluid cooled speakers.  I will be replacing in the near future.  Is all ferrofluid the same or is there different types?
Is all ferrofluid the same or is there different types?


I would use this one from Parts Express (audio parts specialist) you'll know it'll be good quality.
https://www.parts-express.com/ferrofluid-100ul-general-purpose-for-1-diameter-vc--340-540

Cheers George
Thank you George!  
My tweeters are Kef pn SP1353.
They do contain ferrofluid.
I am going to attempt a R & R.  Seems straight forward.
Great thread!  I never knew you could 'change the oil' in your tweeters!
I also never knew that it could 'go bad'.
Once again the Audiogon helps out a fellow member!