A Quick and Easy Way to Filter Dirty Isopropyl Alcohol (IPA) for Washing Resin 3D Prints 

I have tried the micro filter method. What I found works better is to find a clear glass container that will fit in your UV unit. Load the glass container with dirty isopropyl set the timer for 45 minutes. All the suspended plastic will solidify and settle to the sides and bottom. What's left in between is crystal clear isopropyl. Pour it off and use a spatula to remove the muck. If you do it twice even better.

Thanks for the tip. I ordered one. You can also use puppy training pads to put under places that might have a spill AND use them to soak up spills. They wick the liquid away and have the one side that is waterproof. I have been using them for a while now.

Thanks for posting these videos; they give a great overview of what to expect when moving into resin printing

Great idea, I've been looking for something like this. Thanks for the tip!

Appreciate your efforts!

For me I put my dirty IPA in my cure box. Throw on some UV glasses to protect the eyeballs and then let 'er rip. While the resin is curing in the IPA I scrape the sides down with a metal scraper (the resin will cure on the sides and prevent the inside from curing). After a lot has cured out I put a lid on and let it sit for a few days to a week. The IPA is crystal clear doing it this way. The cured resin turns into a block on the bottom, so just pour it off and throw away the block of cured resin.

Nice video Zac and if I ever get into 3D Resin Printing this will be very useful. Take care Zac. Cheers, Huw

Thank you so much!

Very cool, Thank You

They also sell a 10 micron version, though it only appears on their website and not on Amazon. I noticed that they also sell Polyester Felt bags that go down to 1 micron, along with pale heaters which could be used to heat vats in cold winter months through they look a little bulky.

You can buy rolls of coffee filter/tea bag material in a variety of widths that can be cut to fit the size of your bucket filter.

The best solution that I've found is to leave a transparent container exposed to indirect sunlight, so the resin slowly cures and deposits at the bottom. It takes a few days but works very, very well. Then you just pour the clear alcohol out or use a fish-tank siphon pump.

Thanks for the great video. I'm about 2 weeks into this rabbit hole and here is what I'm going to try. ... stage 1... 1. I'll have empty 1 liter ipa containers that I'll fill with dirty ipa. 2. Cure for 20 minutes. 3. Add 1 teaspoon of aluminum sulfate and shake, after which it will coagulate over 24 hours. .....stage 2.... Have 2 two gallon buckets that stack with a ceramic water filter at the bottom of the top one that feeds into the bottom (actually seems similar to your setup). It will be slow, but hopefully somewhat clog resistant and I'll reuse from the bottom bucket. Sort of overkill, but I tend to lean that way. It is mostly passive and I'm hoping I can get a year out of my ipa, although I know I'll loose some along the way. :)

Interesting idea with that filter. I designed and printed a funnel that takes a coffee filter. I pop that into a 1 gallon water bottle.

The clearer alcohol you want to get the denser filters you should use, but that would take much longer, and denser filters will clog much sooner. For 3d printing most of us I think would be happy to get rid of the bulk of the resin, which can be done easier way by siphoning (it disturbs the resin a lot less than decanting), or another method I just discovered (that's actually often used in chemistry) is by separating funnel, which allows to first drain from the bottom the separated resin with only the dirty bottom layers of alcohol, then close the tap, and the clean(er) alcohol will be left in the funnel which you can pour out into a clean container for use. In both cases the wait for good separation is what takes a long time, siphoning/funneling is quick. Btw there's an easy way to do siphoning faster and with minimum disturbance of the resin - just use one of those pumps for big water bottles - they have tube or pipe that can be easily cut or lowered to the necessary depth, and it'll pump the clean(er) alcohol with a push of a button only. After both siphoning/funneling there will be some alcohol left with the most of the resin, which you could put to drain over a dense filter. It'll take long time to drain, but it'll be only a small amount of alcohol that you'll wait for, and you can continue cleaning your prints with the rest. But the only way I can think of for faster separation is by centrifuge. I'm thinking of the easiest method to make DIY centrifuge. One way is by a bicycle wheel mounted horizontal and driven manually/or by pedals/ below the plane of rotation of the bottles (attached to the wheel). The other one might take a bit of investment and hacking, but if you can get cheaply an old washing machine that has its centrifuge still working, you can adapt it to work spinning horizontally (ie around a vertical axis), and you make a bracket for inside the drum so that you can attach couple (or more) bottles, you'll get faster and better separation (most washing machines work between 1200 ~ 1600 RPMs, which at the radius of the drum would produce good amount of Gs).

Use a shop vac to pressure the top OR depressure the bottom to force the alcohol through faster.

There are some filter socks as well that slip into buckets like a garbage bag and you can pre filter , or use just those , maybe even double up the filter, that works OK, but like you said, were just removing the clumps, not the color.

Sweet, just noticed they also have a 100 micron and a 200 micron as well.... picking up the 3 pack.

100% agree with @digodog except that I placed the clear container in the sunlight for a day or two. The IA was super cloudy when placed outside. After sunlight crystal clear IA was left and resin cured at the bottom of the container. Easiest method out there - minimal effort, no filters and no cleanup!

How well is this working for you? Did you ever try it with the pads? How well did that work?

easiest thing to do is just leave the gunked up alcohol to sit for about a month, when you come back you will find it is pretty clean with a layer of the resin on the bottom of the container, just gently pour the alcohol into another container and peeel the resin layer off the original container.

Dang, they're all gone. Hopefully, they'll bring them back sometime.

So im going to get 3 buckets with filters and try to uv cure the rest

I wonder if a thin layer of sand on top of the filter would work well as a pre-filter.

would 400 micron works?? can't seem to find the 25 micron one that would ship to my location...

Do you have any videos showing how you print with mica? I would love to see it and the results. Thanks for the cleaning tip.

Was anyone else expecting him to say “you have so much junk in the trunk”

So much work for such a bad result. This is how you do it: Take the bucket, place it outside in the sun, leave it there for a few hours. Put lid on it, leave it for a day or two. All the resin will settle to the bottom and you can gently pour out the clean alcohol. No filters or work or anything required.

I followed the link to Amazon UK. They want £216 for the filter!! On the US manufacturers webpage it costs the equivalent of just over £10. It doesn't cost £206 to send the filter from the USA to the UK, so something is really, really wrong.