A few months ago I got a couple of rolls of PLA which had been very badly affected by humidity/moisture. One spool in particular was so brittle it was unusable, the other I was wasting 2 to 2.5m of filament just trying to load it into the printer.
I'd read some things about using damp rid in a sealed container to pull the moisture out, but after the spool sat for weeks in a container, it was still unusable.
A week ago I had an idea to use a food dehydrator... And success! Even the spool which was genuinely useless (couldn't even load into the printer) now loads as expected and is printing fine. Pics show the setup.
Step 1: You'll Need...
.. a metal or ceramic bowl and of course the dehydrator
Step 2: Setup 2
Simply put the spool in the bowl and put a couple of layers from the dehydrator in (mine overheated within a couple of minutes if I didn't have these layers in place).
Step 3: Done!
So far both the spools I've tested this on have been at room temperature for over a week and show no signs of the brittle breakage problems.
Even the spool which was completely unusable loads and prints perfectly.