Resin 3D printer operators always have an issue to deal with: disposing of IPA.
IPA is the solvent used to rinse uncured resin off of freshly completed 3D prints. It’s a common material that is easily found in local hardware stores and used by almost all resin 3D printer operators for print cleaning.
But there’s an issue: when the cleaning takes place, the uncured resin ends up in the IPA. This is usually visually obvious: the IPA gets increasingly cloudy as more prints are cleaned. Eventually, it has to be replaced because so much resin is in the IPA that it doesn’t do a proper cleaning anymore.
3D printer operators then grab a new jug of IPA and use that for cleaning. But what happens to the old, polluted IPA?
There are two approaches: disposal and recycling. Let’s talk about each.
IPA Disposal
Since the resin is almost certainly toxic, disposing of the polluted IPA is a problem. You cannot just pour it down the drain, as it will ultimately get into the environment where toxic effects will occur.
One approach is to take the container of dirty IPA to your local hazardous waste disposal facility. This works but requires transporting the IPA, which could be challenging for some people without vehicles or if the nearest disposal site is distant.
Another approach is to eliminate the IPA yourself. There are two ways to do this.
One way is to simply leave the IPA container outside without a lid. Over time, the IPA will naturally evaporate into the atmosphere. However, this also means the resin, which doesn’t evaporate, becomes increasingly concentrated in the remaining IPA.
If you’re lucky, the IPA will fully evaporate, and the resin will be cured by natural UV light from the sun. You should get a container with some dusty shards of cured resin, which are now safe for disposal.
If you’re not lucky, the IPA will congeal into a blobby paste. This is because the IPA contained a significant amount of resin. It will eventually solidify in sunlight, but it takes much longer, perhaps days or a week. Eventually, you’ll be able to toss out the solidified debris.
IPA Recycling
There are services that can do this, but they are sometimes challenging to locate. Often, they require industrial-sized amounts to make sense, so they are not always suitable for small-time resin 3D printer operations.
It’s also possible to purchase a specific IPA recycling device. There are many available because this is a practice commonly done in industrial settings. However, the cost of these devices is almost certainly more expensive than the price of a desktop 3D printer. You’d have to print a large amount of parts over long periods to financially justify the purchase of a dedicated IPA recycler.
Recycling is basically the process of distillation, and there are inexpensive distillers on the market. Some are priced at around US$100, easily affordable. However, most are designed to distill water or alcohol, not IPA. This means that while these devices may work with IPA, you probably will have to adjust settings, change procedures, or make other tweaks. One key change is to ensure the heating is done by electric pad rather than by an open flame, which could ignite the IPA. The major issue is the resin residue, which ends up in the heating chamber. This will have to be dealt with somehow.
For small-scale resin 3D printer operators, disposing of IPA is still a problem. My hope is that the designers of future resin 3D printers will take this into account and create new devices that can clean IPA. Imagine if you could press a button on your washer, and it would go through a cycle to clean your IPA. No mess, no disposal. Just recycling, onsite.
