I find no Google references to using flocculant to settle out resin in IPA baths. While I’d never add anything like this to the FormWash, I would add this in my intermediate wash bucket to rinse off Simple Green from parts that have soaked for a while. Simple Green doesn’t keep resin in suspension like IPA does and, since the IPA bucket has a flat bottom (it’s from the FormLabs wash station), removing semi-solidified “flocked” resin should be simple and more effective than continuously filtering with paper towels.
I don’t think any mechanical means of filtering will work better than gravity, time and paper towels in a sieve. I tried coffee filters but they clogged quickly. The CLEAR resin seems to settle out faster than Grey Pro. Simple Green does a great job of cleaning off the majority of the GP directly from the printer and that goop settles to the bottom of the bucket but residual surface-resin doesn’t separate well in 1st stage IPA wash.
If flocculant works in sewage systems, water/mud separation following gold processing (I saw that on Discovery Channel’s Gold Rush Freddie Dodge), beer processing (Google searches for “flocculant”) and several metal removal processes (that’s where I had some experience with it in a previous job), I would think there is a brew somewhere that can address SLA resin in IPA.
I followed up on your suggestion re: a filtering system. Even chatted with a DuPont chemist today. Seems that a chemical flocculant isn’t an option for IPA. The mechanical filtering systems recommended by FormLabs use a similar process to what you were referring to on the Google link. A chemist who works in large scale water treatment applications suggested this so you may be on to something. Paper towels and coffee filters filter 20 micron particles and I need something about half that size. He linked me to this:
I stumbled across a discussion on a model railroad group where the original poster asked about straining resin. A respondent based his suggestion on this:
I tried it in a small Mason jar, with the added water per his suggestion to bond with the salt, and the Simple Green I use in 1st stage after printing was separated from the 99% IPA resulting in greatly improved clarity. There is a layer of unused salt on the bottom, then a green-tinted layer with some particles in it, then the clear(er) IPA. Not sure if just the SG is being removed so I’m trying a gallon-sized experiment now. I may just bite the bullet and buy the filtering set shown in the Amazon link.
What you are attempting is analogous to removing alcohol from wine, ie remove an alcohol from a complex solution. There are a number of methods in use in the wine industry, but none are as simple or cost effective as basic distillation.