PVA becomes dirty when dissolving

[OscarLoddesol 0]

Hello,

 

I recently tried to print a model of architecture, that needed som PVA support. During the print, everything looked white and clean, but after dissolving the PVA, i got some brown leftovers. It is removable, but its a lot. Any tips on how to avoid this problem? Any tips on removing the brown leftovers? 

 

Thank you 

 

 

[gr5 2,173]

I've never seen pva get that bad.  Did you submerge the entire print in water?  For how long?  These should all dissolve away.

 

So most problems with PVA have to do with humidity.  Water gets in the filament.  Do you have the MS (material station)?  How long as the PVA been in the material station (if you have one)?

 

You may need to dry your pva.  You can tell when pva is wet as you see steam coming out of the nozzle and you can hear it popping and sizzling (boiling water).  Also the pva is foamy white.  Like snow.  If the pva is dry it comes out of the nozzle clear and transparent.

[Lodden 1]

Hello - I am the thread starter, but i created a duplicate account..

 

Yes I submerged the entire print in a removal station. I changed the water before i submerged the print. The PVA was also fresh out of the box, and came out transparent from the nozzle.

 

The print stayed in water for about 24 hours, and the dirty parts were still a little "slimy", what is the recommended dissolving time?     

[Torgeir 243]

Hi @Lodden,

 

All water contains "natural organics and minerals" and this are varying much of where you live.

This may colorize the water like brownish or even yellow, but it is not that easy to see this colors in our drinking water.

 

When dissolving PVA from printed object, it is best to remove as much as possible before using water for removing PVA from the model. As water dissolve the PVA, it will at some point be saturated and the process slow down. Then we remove the slime, dissolves it more with water and flushes it down the drain. Then we do this process over again as many times as needed, -sometimes also by using a brush.

 

After all this work, it is very important to clean off all of the "eventually" slimy remain of PVA that could collect up in your cleaning container. Remains from previous "PVA" cleaning may dry and stick, becoming a "new" peace of PVA to be diluted and collecting some new brownish organic from the water. If this go on for some time, this will color the stuck and glued PVA.

 

You can submerge your model into a container with water *(35-40) deg. C. and wait until this PVA "particles" become soft, the use a hand shower *(with moderate flow) and a brush to remove the "slime" with.

 

I think the long process time also dissolved "old" stored PVA that was collected somehow in the removal station.

Normally we say the processing time is between 8 and 12 hour (in tempered water), but sure depending of size of the model and support.

 

Thanks

Torgeir