Last Dregs of Resin - Combining Same-Batch Resin Cartridges

I’ve often had a tank where one doesn’t have quite enough resin to finish my next few jobs, but definitely enough to extend the life of the next cartridge of the same stuff!

I realize from an official standpoint, it’s not great practice to incorporate ‘old’ resin into a brand new cartridge that has space to accomodate the influx. But, when both are being used in close proximity timewise, from the same batch… and if the user is willing to hazard the risk… is there a graceful way to consolidate the last bit of resin from mostly-used cartridge to the newer one, without spilling?

Is there a way, perhaps to connect the two tanks temporarily together so one could drip into the other? I’ve found it awkward to manually fill the resin tray with these dregs and would much rather let the Form 2 determine how much is needed. The last time I tried, the resin poured way faster than I had thought it would… took forever to carefully move the excess out of the tank without making a big mess.

(IE: Like a way to connect the bite valve of one cartridge to the ‘shampoo cap’ on another for a few hours, or connect the two caps together?)

Any thoughts on if you’ve done this, or reasons (besides cross contamination of the tanks) why this would be a terrible idea? What happens if more than 1L of resin gets dispensed from a tank - does Formlabs software stop dispensing from that tank?

look up smart funnel on amazon or a lotion saver coupler. There are all sorts/sizes out there to do exactly what you are looking for.

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Interestingly, a long time ago when Formlabs still used bottles, they released a part that did exactly what you’re looking for:

I haven’t seen the equivalent for cartridges. If you CAD something yourself, be sure to share it!

I usually just let the machine deal with this for me by leaving the cartridge installed until it’s completely empty (and when it nears that point, avoid doing prints that will use up more than one tray worth of resin). Unfortunately it does require overriding some annoying warnings at the start of the print.

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Someone on a formlabs Facebook group made exactly that.


An adapter, stand, funnel, or an intermediate vessel are all better ways to go, but…

…When I’ve got a nearly empty cartridge to drain into another cartridge, I sometimes pull the lower plastic part off the cartridge (which can be recycled if it doesn’t have any resin on it, by the way, it’s even got a 5 PP symbol on it), and then pull the bite valve off the old cartridge and rest the barb in the top of the cartridge that’s getting the resin. It takes a little to balance the draining cartridge up there, but not much.

Of course, the work surface I do this on is stainless steel, in a well-ventilated lab, with lots of cleaning supplies.

Whoa, how did I miss this? I could have sworn I did a search on Thingiverse the other day for this exact thing. I guess my keyword game isn’t on point. :slight_smile:

Thank you!


Ike, I have a craft room with a wooden floor. It’s pretty much the exact opposite of your nice cleanroom environment. :slight_smile: Lots of stuff everywhere that I really don’t want to see contaminated with resin if things get out of hand. Though I am glad to have the alternate idea if I have a stainless steel sink not filled with dishes for a long enough timespan to do such a transfer. (ha, like that will happen. I’m a terrible housekeeper, I’d rather be making things!)

It’s always good to have a few extra options of how to accomplish something in one’s back pocket.

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I think we have a better method. You need two cartridge caps, remove the snap lids and a good portion of the guts from both. Connect them together using sealing heat shrink (Amazon) with the adhesive. It works great! Rinse in IPA and repeat. I track usage in my dashboard so that I won’t try and add too much. It works well for us.