Newb PVA questions

[Involute 0]

Newb here.  I’m thinking of buying my first 3D printer and leaning toward the S3.  
 

1.  Does PVA dissolve faster in warm water than it does in cold?  How much of a difference is there?

2.  Does PVA dissolve faster with agitation of the water than in still water?  How much of a difference is there?

3.  How long does the PVA dissolving process take?  I realize this depends on the model, but any guidelines or anecdotes would be helpful.  I’ve seen some timelapses on YouTube, but none that included a clock.

 

Thanks.

[Framar 38]

Warm water really makes a big difference (2x faster). I usually drop my 3D printed parts in a large bucket. Since I don'T have any agitator I replace the water every  2-4 hours. Usually it takes 8 to 24 hours to dissolve the PVA depending on the quantity to dissolve.

 

You can get it done quicker if you remove most of the PVA with pliers first. Or even better, if you can use PLA as support structure and use PVA only for the support roof. Then you can get really clean part quicker but not all part design is good for that option.

[Involute 0]

Thanks.  Do you replace the water to keep it warm (which could be achieved with a heater) or to preserve its purity?

[Involute 0]

Also, does the slicer allow you to specify a mixture of PLA and PVA for support structures, and can you specify it for just certain structures?  Otherwise, how do you do what you suggest?

[D95 3]

I drop parts into one warm water bucket for 10-20 minutes, then manually pull off as much PVA as possible. Then transfer to a larger bucket with clean warm water.  Water saturated with too much PVA dissolves off part slower. I usually allow overnight, and sometimes need a second day to clear PVA out of inside corners, or small holes on parts. Especially blind holes.

I am sure circulation, and constant warm water would help, so I am planning to try something like this below, that others have used.  Not sure how long it will last.

 

VPCOK Sous Vide Cooker Accurate Immersion Cooker Control Temperature and Timer, 1000 Watts, 100-120V, Sous Vide Cookbook Included https://www.amazon.com/dp/B07HJ2F6JN/ref=cm_sw_r_em_apa_i_GNkIFbYF341AJ 

 

 

[Carla_Birch 116]

19 hours ago, Involute said:

Also, does the slicer allow you to specify a mixture of PLA and PVA for support structures, and can you specify it for just certain structures?  Otherwise, how do you do what you suggest?

Yes, you can pick to have the support supports as PLA and the floor and roofs of the support in PVA, so only the support parts that make contact with a print is PVA what saves a lot of PVA use and then also cost. But keep in mind you need to be able to get in to remove the PLA parts of the supports, so thats something that you need to think about each print.

[Involute 0]

51 minutes ago, Carla_Birch said:

But keep in mind you need to be able to get in to remove the PLA parts of the supports, so thats something that you need to think about each print.

Can you indicate that only some support structures (e.g. exterior ones) are to be PVA + PLA while others (e.g. interior ones) are to be all PVA?

[Carla_Birch 116]

4 minutes ago, Involute said:

Can you indicate that only some support structures (e.g. exterior ones) are to be PVA + PLA while others (e.g. interior ones) are to be all PVA?

Far as i know you can not do that, but it would be could if you could.

[Gero 54]

Dissolving almost daily PVA prints.
I use a heated magnet stirrer for all my PVA prints with a 2 liter bucket. 
Into the bucket comes already warm water to speed up the process. 
The bigger the bucket is, the more time it takes till the water is saturated, which slows the process down by a lot. 
So I change the water after the first 2 hours. After that I let the water do its thing. 

Most of my parts are in water for like 16-24 hours. Smaller parts for like 8 hours. 
The time could be less with some manual removal but I rather give the parts 1 full day for dissolving and drying so I have time for other things than rushing some individual parts. 

[Involute 0]

Any idea what temperature the water is?  What do you do with the waste water?  Just pour it down the drain?

[Gero 54]

Around 30°C is great. But 25°C is also still working fine. My experience is that it should be at least 20°C. Anything lower is working very slow. 
You can pour it down the drain if your sewage is connected to a sewage treatment plant. 
I also make sure to never have solid or even gummy like bits in what I pour down the drain to make sure there is nothing in there that could cause constipation.