# How much resin is wasted?

I run a 3D printing lab at a college and we’re trying to determine how much resin we waste, for the purposes of figuring out our pricing structure. Anyone have an idea how much resin is left in an empty bottle (we have a Form 1+), or is wasted in terms of cleanup or what is left on the build platform?

Thanks!

The support structure is what wastes the most material, you can calculate the volume of the part separately to find out what the volume of the support are.

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Hi Zachary,

We’re already taking support into account, just trying to figure out what gets wasted beyond that.

The resin that you wash off in IPA can be up to 50% of a part volume, depending on a structure of the part. The more cavities, surfaces and the smaller the details are - the more places for the resin to stay in without dripping back to the tank.

@Konstantin_Dani That’s interesting, I never would have thought of that. Do you ever leave the finished build plate sitting in the machine for a bit so resin can drip out?

50% seems a pretty big number. A printed part that’s 100ml of resin isn’t going to take another 50ml out of the resin tank when it’s removed unless the part is very poorly designed and that extra resin is trapped inside the part.

What’s still stuck on the surface? It’s obviously a function of a few factors including the surface area and surface texture and the resin type and how long you let it hang on the build platform before you take it out to wash it off. But I can’t imagine it adds up to more than a couple of mL worst case. Think of how much resin you’d need to paint the surface of your print with a brush and that’s about how much resin is probably stuck to the outside of the part when you remove it.

How much you leave in a bottle is a function of how long you’re willing to let it sit upside down and drain. I would bet you lose maybe 10ml or so to the bottle unless you “squeeze it dry” (let it drain overnight, in which case you probably get pretty much all of it).

How much you leave in the tray is also a function of your actions. I’ve had good luck managing my prints and resin level in a way that I’ve left very little resin in the tray when I finally replace the tray (I make it a challenge to see how well I can do). Though below a certain level printing might become unreliable since areas can go dry. The tray holds 100ml when filled to the fill line. If you have a Form1 (I do) you might use 75 of that 100mL before you end up with dry spots. If you have a Form2 (I do), it looks to me like the wiper guarantees you can use all but maybe the last 10mL or so.

Thanks, Randy! That was really helpful. I didn’t know the fill line was 100 mL, that’s a good baseline to have.

The castable resin is expensive so here is what I have done to eliminated waste.

When the black plastic on my Form1+ platform deform I removed the edges because resin started to get inside.
I just put a wire on the platform handle and after printing I hang the platform at an angle
to let the resin drain for about 15 minutes.

Also, the clear resin is less viscous without any pigment so it will flow off the material more easily

Thanks! All good tips

@evert_gonzalez How stable is the handle of the platform when you have it hanging there?

I used round wire and it stays there fine.
If you use square wire it will be better.

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