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!
128x128b_limo
If you are interested in getting your hands dirty, consider a new kit instead. Built the whole thing from scratch. :)
Erik, I asked you a while ago, but you never answered.  I read your paper on a pair of speakers you built, but asked how many pairs you have actually assembled?  Is it the one pair, really just curious, I am not handy and wouldn't dare try.
@jetter

I answered you. Go back and look.

But truth is I have never built cabinets. The cabinet for the SNR-1 was custom built by Lee Taylor of Taylor Acoustics.

The other 2 models used kit boxes. In all cases the part selection and schematics were my own.
Sorry erik, I must have missed your answer.  I wouldn't have expected you to build the cabinets, a whole other deal requiring the woodworking tools.  Just buying a kit with all the parts preselected by someone else seems adventurous to me.  As I mentioned, I am not handy in this way.

I have read several articles by people who have built speakers (not the cabinets) and the tuning via crossover part selection seems not for the faint of heart.
Dried up Ferrofluid?



I posted this up 6 months ago, why some were complaining about harsh Thiel tweeters that get non-linear distortions with sticky old Ferro Fluid that’s gone like tar, it has to be cleaned out, just don't add new fluid to a gummed up voice coil gap, you'll be wasting time and effort  

A lot cheaper than buying new diaphragms. $10 for new fluid vs up to $200 each for new diaphragms, and they could be clones/fakes.
Still have to clean out the old fluid doing either.

Tweeter Ferro Fluid and how to change it.
https://www.parts-express.com/ferrofluid-100ul-general-purpose-for-1-diameter-vc--340-540

https://forum.audiogon.com/posts/1843203

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

Cheers George