Mad!!! Bad humidy indicators from Aliexpress

[RudydG 62]

We all know how sensitive some filaments are when it comes to humidity.  Over the years i learned it the hard way, and last year, i realized, that storing filament is a delicate task.

 

So i bought some boxes, filled them with 1 kg silicalgel, and put in each box a humidity meter. So far so good. Reading was constantly under 20%, everything fine. Until i took out some rolls to work with, and got a bad feeling, almost all my special rolls gave moisture problems (2 types PVA, Nylon, greentec  and TPU. This morning i decided to check the meters, and they are all faulty. They are in my living room now, where the humidity is now 47, the meters (3) still indicate 15% after 2 hours....temperature reading is ok.

 

So i got caught, even though i am not the "cheap buying" guy, relying on a cheap part.

Just had to write it off me !!!

 

Greetings,

 

Rudy

 

 

 

Edited December 9, 2018 by RudydG

[Smithy 1,144]

Humidity meters are always problematic, especially the digital ones. I store a lot of cigars in 3 humidors and have tried many of them. Ok, for a humidor you need a much more accurate measurement, but the meters I have tried differ up to 10% from each other. Best and most accurate are analog hair meters, but they need regular calibration and are not cheap.

 

And most humidity meters are just accurate within a specific range, and outside of this range, they show some phantasie values. Most meters are made for typical living room conditions.

 

I store my sensitive filament in single Lock & Lock boxes and just put one or two 20g silica gel packs into the box, without a humidity meter. I also thought to buy some cheap meters which are roughly working, but due to your experience, I should overthink it again.

[geert_2 557]

What about the indicators that flip from blue to pink at a certain moisture level? These seem to be quite stable, until the stuff gets defect and becomes yellow-brown instead of blue/pink. But I have no idea at which level they flip over, nor what the hysteresis is, if any...

 

[RudydG 62]

I know, i have these, but they are "packed" in black nylons (stockings?) so the color was invisible.

 

[fergazz 60]

I live in a very humidy city, Rio de Janeiro, and I had a cheap humidity meter that had very low tolerance, about + or - 8% but it broked, realy bad quality one. 

 

Nowadays I use another one, still cheap compared to the professional ones but the values are much closer to the official mesurement made by climatic organ in my city, they mesure in my neighbohood so it’s a good source to compare. I believe it have + or - 3% accurancy but it just work to me to know when to dry my silica gel and maintain the humidy of the filament.

 

During these years I learned that silica gel only dryes the outter area of the filament, inside still humity and the only way to eliminate it is heating (IMPORTANT: below the glass temperature of the filament to don’t destroy your filament properties) and with air circulation spining around the roll or filament peace. For this one the best choice should be a PrintDry (https://www.printdry.com/) and they pointed in their website how it works: view photos or check full info in this link 

https://www.printdry.com/science

 

 

 

And the last photo attached is a information about hygroscopic materials, it’s missing TPU information that I believe it’s very hygroscopic but not as much as Nylor or PVA.

 

 

I’m seeing some guys using food dehydrator to dry filamets, that’s should be a cheaper choice but need some ajustments to fit the rolls as showned in this recently 3DMN video: 

 

 

I hope those informations helps anyone!

Edited December 23, 2018 by fergazz
video inclusion

[RudydG 62]

Thanks for your post, very informational.