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!
Ag insider logo xs@2xb_limo
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!
Guess I’m officially a cheapskate. 

I made my own ferrofluid. I have a bag of ferrite cores I bought for making coils. I used a smooth knife sharpening stone and ground the ferrite core into a fine powder. I used 30 wt Mobile 1 synthetic oil. I mixed the powder into 1 ounce of the oil until it was dark like strong coffee. Then I let it sit and settle overnight. The big particles settled to the bottom. Then I poured the clean ferrofluid into a clean glass bottle with a tight cap. I used an inkjet refill kit syringe to inject the fluid into my dome tweets and midranges.

BTW, that was 17 years ago. Mobile 1 is more stable than regular ferrofluid oil; it has heat stabilizers, antioxidants, detergent, in its additive package. Probably time to check my drivers and do a refill. Also, I used contact cleaner to FLUSH OUT the old ferrofluid. Paper tape will not remove all the old gunk.
quincy196 posts03-14-2020 12:44pmThank you George!
My tweeters are Kef pn SP1353.
They do contain ferrofluid.
I am going to attempt a R & R. Seems straight forward.

👍
And if not old enough yet or sounding ok, just like doing preventative maintenance.

I used contact cleaner to FLUSH OUT the old ferrofluid. Paper tape will not remove all the old gunk.
I think even petrol would be fine for the magnet gap, but anything on the voice coil something milder as the coil insulation lacquer needs to be looked after. 

Cheers George