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Off Topic Hobbies => 3D printing => Topic started by: Microdoser on June 22, 2021, 03:42:01 pm

Title: Small cost free tip for filament drying
Post by: Microdoser on June 22, 2021, 03:42:01 pm
If you order components from Digi-Key, sometimes you get a little moisture detecting card in the packet that turns pink in the presence of moisture.

I have found that if this is placed in your filament dryer (I use a food dehydrator) then, even if some circles have turned pink, it will turn blue again and can be taped or glued to a filament roll to indicate if it has been kept somewhere too moist.

Obviously it will react far quicker than your filament, so it should not be trusted to indicate whether your filament has become waterlogged or dry, but it will indicate whether the environment it is in is too damp.

If you use moisture absorbing crystals, it will let you know if they have stopped working also.

Of course, a proper hygrometer will do a much more accurate job, but this is free, and can be used on a roll by roll basis, and uses no power.

Myself, I have a BME280 connected to an arduino that lights a small red LED when the moisture goes over 40% for 1/2 an hour and only noticed this because I was curious whether the card reverted to blue when drying out some filament.

Hope this helps someone
Title: Re: Small cost free tip for filament drying
Post by: mawyatt on June 23, 2021, 01:34:12 am
Great idea :-+

Now to get DigiKey to supply a few more moisture cards in my next order ::)

Best,
Title: Re: Small cost free tip for filament drying
Post by: mawyatt on June 23, 2021, 01:42:07 am
BTW what dehydrator do you use? Living in Florida, we always have high humidity and being new to 3D printing I've already experienced the brittleness with some PLAs that trashed some prints.

Best,
Title: Re: Small cost free tip for filament drying
Post by: Microdoser on June 23, 2021, 11:27:36 am
BTW what dehydrator do you use? Living in Florida, we always have high humidity and being new to 3D printing I've already experienced the brittleness with some PLAs that trashed some prints.

Best,

I just bought the cheapest one on Amazon that would fit a filament roll in (by cutting out alternate shelves). It was £28.99 delivered. 280W, 35-70C, round, 5 tiers.

https://www.amazon.co.uk/gp/product/B08G4MHFKT/ref=ppx_yo_dt_b_asin_title_o00_s00 (https://www.amazon.co.uk/gp/product/B08G4MHFKT/ref=ppx_yo_dt_b_asin_title_o00_s00)

Works fine. I have checked temperature with a proper sensor and adjusted the dial to get a max of 48C inside (so PLA doesn't degrade) and it gets pretty dry. I also keep any of those little moisture absorbing crystal pouches in there that Digi-key deliver, although they require an oven at 120C for 1-2hrs to recharge. As I don't use many types or colours of filament it's where I keep the filament I am not using, makes it easy to just turn it on for a few hours before I need to print.
Title: Re: Small cost free tip for filament drying
Post by: vintagepc on June 25, 2021, 01:18:00 am
I've definitely used one of those too... interesting to watch it change slowly but the blue beads are still blue until quite a bit later.

What's particularly interesting is that it also shows plastic is surprisingly moisture permeable over time; I put one together with some freshly dried out dessicant packs (warm from the oven) in a vacuum sealer bag and it still turned pink at 10% after a few days. Certainly much slower than in ambient air, but these indicators are useful to see at a glance if the dessicant packs might need changing - especially if you're like me and have amassed a pile that do not change colour from previous filament purchases.

I like to keep a big bag of "fresh" ones ready to go so I can quickly chuck in some fresh ones if I open a roll.