Shaking the resin absolutely helps. I used to do it by hand and recommend at least 10 straight minutes. I’m one of those folks who hacked together a mixing appliance, and now use it for cartridges that have been sitting a while (letting them rotisserie for 30 minutes to a few hours depending on my rush). My usage pattern often entails long periods of time between prints (weeks / months / even excess of a year).
What you did accomplished two things:
- filtered out any bits of cured resin or other contaminants
- mixed the components of the resin
The pigments settle over time. Some resins even stratify into layers if left standing long enough (e.g. months), forming a gooey consistency on the bottom or top (I’ve found Black v4 is notorious for this).
I’m sure if you stir long enough and very thoroughly it will accomplish the same thing. I don’t bother to drain the tanks myself unless I think they need filtering, but I do stir until I see all the resin is completely consistent, then double that amount of time to be sure. Sometimes I do this if it’s been more than a week since my last print, and certainly if there’s any obvious inconsistency looking at the contents of the tank. The wiper or mixer alone doesn’t seem to achieve the same level of homogeneity. (It also doesn’t take care of the thin, sticky layer I’ve found forms over time and needs to be gently scraped from the bottom of a tank containing Rigid 4000). I’ve suggested Formlabs give us a “mix” procedure we can perform under the Maintenance menu that heats the resin a little and just moves the arm back and forth for like 30 minutes.
I don’t have a regular “agitation schedule” for cartridges in storage. Once and a while I might cycle them all through my rotisserie (couple times a year?) but primarily I just do it before I use them. Before the contraption, I used to go and flip my stored cartridges upside down now and then for what it was worth (very slow mix).
One thing to watch out for is an excess of air bubbles that have formed right after you shake (especially if you were vigorous, then remove the cap and pour the resin out into the tank manually). If I shake by hand, I typically let the resin stand for about 10-30 minutes afterward (either in the tank or the cartridge) before starting the print to give the bubbles a chance to dissipate.
All this has helped me get more lifetime out of some of the resins (Black in particular).
If you’re in a rush or lazy you can certainly take a less conservative approach as to duration and frequency.