Saving Resin

Just wanted to know if, after a print, is it ok to squeegee the unused resin off the build platform and put it back into the tray?
I didn’t think this would be an issue and it seemed to be a waste of resin to just discard it.

I remove the print and unless a piece of the base has cracked off I simply replace platform leaving all the residual resin in place.

Yes, but if I don’t use the printer for a day or two, I’m afraid of the thin layer of resin drying out.

I don’t think there’s much volatility to the resins. They aren’t made from water, they’re more like an oil. Shouldn’t dry out, only cure. If drying-out was a problem, you’d get a skin on the surface of the resin still in the tank. Just leave it and the resin is “reclaimed” when the platform submerges at the start of the next print.

That being said, we’re talking about amounts of resin that are too small to matter. I bet you’d be hard-pressed to squeegee even a milliliter. You probably carry a lot more than that away on the surface of the print.

Also, it’s OK to leave the print on the build platform for a while. I generally wait until I don’t see any drops falling off. Maybe 15 minutes or so. Not so much to reclaim the resin for the next print as to minimize the rate at which I have to replace the IPA in my wash tanks…

@Randy_Cohen is right: resin doesn’t dry, it photocures. As long as it stays in the dark or under the orange cover, it will stay liquid.

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Ok, understand. Thanks.
So here is a new question, after I send a file to the printer, can I turn off my computer, and how long can I wait before starting the print? My wife gets home hours before me, and would be great to have the printer ready where all she has to do is press start on the Form.

The printer does not need an attached computer to run. You can wait as long as you’d like. After the print is uploaded, you could unplug it, ship it, store it for a year, unpack it, plug it in, insert a cartridge, and start the print. If you have your printer all ready to go, the only limit between sending the print and starting it is the resin shelf life. :slight_smile:

You can also leave resin in the tray after printing–just remember to stir it thoroughly before you print again, I just use the scraper to stir it. If it’s been a while then the resin might look weird as you stir it but after a bit it will be fine. The pigment will settle out of the resin over time so it needs to be mixed back in.
Also, you can leave a print in the printer after it’s finished for a while without any issues so if you want to start a print knowing that you won’t be back to remove it once it’s done then it won’t be an issue.

I’ll be damned if I’m going to stir resin in the tank by hand now. That’s why FormLabs gave us “the wiper” (AKA “the stirrer”)…:grin:

But for a Form1+ I agree, opaque resins need to be stirred before use. Even a couple of hours is enough to settle the pigments out. Not necessary with colored resins like Tough, though.

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The wiper keeps the resin mixed during printing and also pushes away possible bits of cured resin along with exposing the PDMS to oxygen which helps the print not to stick to the bottom of the tray and increase the lifetime of the PDMS.
Outside of the actual printing it doesn’t mix the resin enough, especially if you haven’t printed for a while you need to stir it for like 5 minutes to get it fully mixed again. Even after a couple of days it needs to be stirred, especially important for the beginning of a print to make sure it sticks to the bottom of the platform.

Well. Since I only use clear resin, I guess no issues with stirring or wiping.

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