RE: Filament humidity range
just FYI, most of you already have a functional dryer in your kitchen. Your oven light will warm the interior to 85 - 90°F which should help dry out anything you put in there. Might take some time but someone with a hygrometer can do some testing.
RE: Filament humidity range
Actually, all of us in on this site have one; your heated print bed.
There are plenty of articles about using the bed to warm and dry your filament. Plus you are usually heating the bed anyway. I won't use my oven for non-food stuff. That is my personal feeling and action, and I'm not telling others to follow suite, do what you want with what you have. I'm sure we breathe in more plastic just walking around anyway (but makes you wonder if we are adding to it - we are).
RE: Filament humidity range
One comment. RH% is dependent on temperature. If you have 30% at 25 degrees, at 20 degrees it will be higher at over 40%. There are tools on the net to compare between them.
Drying with desiccant is a slow process and not the best but for storage it helps if you don't have a dryer.
I have about 1.5kg in both bins with 6 or 7 rolls of filament. I have 21% at 19 degrees right now. Drying the silica gel is the biggest headache but it helps to heat the workshop in the winter time.
RE:
Good catch. I always overlook dew point, wet-bulb temp, and the like.
I don't dry with silica gel. It is, like you say, much too slow.
I use heat, moving/forced air, and activated alumina. Much quicker. And I tend to dry then store in a vacuum bag with a jar of desiccant in there. I'm an old cable dawg, so anything like a cable air dryer works for me.
I only need to get sub 30%.
RE: Filament humidity range
Just read a paper on the differences between Activated Alumina and Silica Gel. I was about to order more Silica but that is now going to be changed. They are about the same price from what I see.
From the paper, Activated Alumina was 100% effective and Silica Gel is 77.9% Activated Alumina took the RH% down to 0.0 while Silica Gel stuck at 9.7% in the closed test.
RE: Filament humidity range
I don't have the ability to test that, precisely, but my anecdotal evidence (professionally and as a hobbyist) has seen a vast difference.
I do, however, use silica to store with the filament, as it is cheap (meaning I have a ton that has accumulated over the years) and I don't need it super-dry.
RE: Filament humidity range
Just a note. I ordered some Activated Alumina from AliExpress. C$ 19.95 /kg. Will have to test it.
A test I have tried with silica gel. 2 hrs in an oven then sealed in a jar with a temperature/RH sensor and it won't go below 25% at 19° More testing.