What causes these holes in my print?

[nicklas 0]

Hi, 

I printed this model in PLA with PVA support, and I noticed these holes when the PVA was removed when submerged in water.

 

https://imgur.com/a/NlDNpqg

 

Do you have any idea what causes it? 

 

The way the cure is printed looks like the way the support was printed, which is distinct from the rest of the layers, so maybe it has something to do with support pattern?

 

Thanks in advance!

[geert_2 557]

Could it be strings from the support material?

On the place where there is a string, this room obviously can not be occupied by PLA anymore, thus leaving a gap in the PLA after dissolving the supports.

I am not saying this is the cause, but it could be?

 

[nicklas 0]

Definitely an interesting thought!

 

I'll try to print it again – it might have been a fluke.

[geert_2 557]

Although I don't have a dual nozzle printer, I have read and seen on photos that PVA support material is very prone to stringing. So I doubt if you can totally avoid it.

 

But you can sure try to minimise it. At least, be sure to keep the support filament very dry, and dry prior to printing if necessary, and preferably keep it in a closed box while printing. Make a box yourself or buy one of the available models (I don't remember the name, you will need to search the forum for this).

 

[gr5 2,172]

My guess was also that PVA strings caused those holes.  I'd look at the part before you submerged it (take a photo) and also you can look at cura layer view and see if that's where the pva nozzle first gets close to the part after switching to the pva core.