PVA too dry? Brittle and cracks in feeder

[double0jimb0 0]

I store PVA in sealed box with the "under sink" dehimidifier that gets recharged by pluggin into wall: https://www.amazon.com/Improved-Eva-dry-333-Renewable-Dehumidifier/dp/B000H0XFCS/  These things I think are power dehumidifiers.

 

I monitor humidity with two battery powered gauges, humidity stays at a constant 10%.

 

I went 3 months between PVA runs, spool was maybe 6 months old total by this time.  The filament was so dry and hard that it cracked in the feeder on our S5.  

 

When I managed to get the filament all the way to the extruder without cracking, it would extruded extremely unevenly and almost in a pulsing pattern.

 

I put in a new bag of Ultimaker PVA, and it extrudes perfectly.   

 

So, can PVA be too dry and does it have a shelf life?  Others experience here?

[gr5 2,004]

I never heard of this problem but 10% is lower humidity then I get with a sealed bag and 45 gram packages of dessicant so maybe you are correct - maybe you got it too dry. 

 

Is it only the outer meter of filament that cracks easily?  Or if you throw away the outer meter of filament is it okay after that?

 

I have PVA that is 2 years old and still works excellent.

 

[GEE 9]

Is there a way to rescue it, if its too dry? 

[NBull 14]

PVA can get too dry, and will make it brittle. but I have not heard of a dessicant bag casing it. Thats more likely to happen when using a dehydrator or oven.

 

Sunlight can also make it brittle btw.

 

To save the spole, I don't know. best thing would probably be to stor it in a terrarium where you can monitor and adjust the humidity precisely. 

 

I would personally put it in a big air tight container 50-60L whit a humidity monitor and try to keep it at 20% just opening the lid to adjust if it goes below. or put som drops of water in the container if its way to low. My theory is that is better to raise the humidity slowly.

Edited November 26, 2019 by NBull

[gr5 2,004]

10 hours ago, GEE said:

Is there a way to rescue it, if its too dry? 

I have no idea.  I would leave it in a 30 to 50% humid environment for a few days and see if it gets less brittle.  If it does I'd go back to storage that is more humid than 10% and less than 50%.  It sounds like NBull recommends 20%.

[double0jimb0 0]

Thank you for all the inputs.  

 

I do have it on the desk right now outside the desiccant box.  It's pretty dry here (Denver) in general, shop humidity bounces between 20-30% (but currently blizzarding with 92% humidity outside...)  I will put it back into it's own desiccant box in a couple days and monitor humidity level over time.  Aiming to level out at 20%.  Will report back with results.

 

As for: 

13 hours ago, gr5 said:

Is it only the outer meter of filament that cracks easily?  Or if you throw away the outer meter of filament is it okay after that?

No, the whole spool is super brittle.  

 

And it is not possible it has seen UV degradation, it is in a windowless workshop.

[GEE 9]

Currently my PVA & Breakaway is stored in a Polybox. Working well so far, but we´ will see how it works in a few months... 

 

 

[GEE 9]

Tried it out today - 15 weeks in the Polybox and doing fine:

 

[Smithy 1,135]

The Polybox is a nice working add-on.

Thanks for your feedback!

[NBull 14]

On 12/2/2019 at 10:47 AM, GEE said:

 

What printer is this, the s3?

[GEE 9]

Yes

[BiMNrd 11]

your printed is so clean inside.. I have the printdry.. not too much of a fan.