This IPA costs money – but it can be recycled! Hey guys,
I do a fair bit of resin printing and get through a lot of IPA to clean the prints,
but rather than fork out for more, I eek it as much as possible.
Here’s your typical used IPA, dirty and cloudy. But we can get this clean again.
Initially I use one of these resin straining filters initially. Pour the used IPA into
a clear bottle, plastic or glass, and filter out any bits of solidified resin that may
be there. What’s left is cloudy and mess and this
is full on uncured resin. It’s very easy to get rid of this. Just place it on a windowsill
– indoors – for a couple of weeks. Make sure it’s out the reach out kids and
mark the bottle to make sure no one drinks it be accident.
There’s no rigid time frame involved. Just wait for it to become clear again. There’s
more than enough UV coming through the glass to do the job, even on a window that doesn’t
see direct sunlight. Eventually you end up with something like
this. Hopefully yours will be a little clearer, but I’ll come to that in a minute. Now we
need to filter this again to remove the cured resin sediment.
I’ve found paper coffee filters to work very well and I purchase these cheaply on
Amazon. Just place them in a funnel and pour gently into a container.
Well, that’s the ideal way of doing it, but the problem is the funnel blocks off very
quickly. The funnel has quite a small opening through which all that liquid has to flow,
so despite the size of the filter paper, the only THIS parts actually filters. And once
that clogs, you need another filter paper which is very wasteful.
So I designed this filtering funnel. It’s essentially one funnel inside another. The
innermost funnel has lots of holes in it, meaning that more surface area of the filter
to act upon. I simply printed this on an FDM printer though a resin print might survive
a while. Trust me, this is a vast improvement on a standard funnel, though paper filtering
is still not a fast process, but it is quite efficient.
It’s easy enough to design your own filtering funnel, but if you fancy supporting me, you
can buy the STL file on my Etsy store. From there you can rescale as you wish, and it’s
a simple, support free print and the funnel works great. Alternatively, maybe a simple
sieve would do the trick. And that’s how I recycle my IPA and double,
triple and even quadruple the life of it. However, I find once I’ve repeated this
process several times, the recycled IPA takes on more colour, like this one, and, perhaps
because I use a lot of speciality resins, becomes a little sticky and just doesn’t
clean properly. This got me wondering if there was another
way to clean this, and I found myself thinking back to my school day chemistry classes. And
once I stopped thinking about Miss Randall and her delicate handling of my Bunsen burner,
I thought about distillation. In a nutshell, distillation converts a liquid
into a gas and then condenses this back into a liquid. The process is perfect for removing
impurities – and that means another mad experiment for me.
Now a quick word of caution here. Boiling alcohols is a volatile affair and you’re
dealing with very flammable materials. As well as obvious safety concerns, there could
well be a question of legality in some areas, as you’re effectively running a still.
I decided to use a water bath to support my distillation vessel, as this should hopefully
slow down the heat transfer and make it more controllable.
The filtered IPA goes into the flask. The flask goes into the water bath – or in my
case saucepan. These sit on a tripod above a Bunsen burner. A hose from the flask is
connected to a collection vessel which sits below the level of the flask.
So, the water in the saucepan was heated to around 85 degrees Celsius. This in turn heated
the IPA to the same temperature and causes it to boil. This generates steam or vapour
inside the flask and thanks to my makeshift bung, the vapour now had nowhere to go except
the hose, where it cooled, condensed and theoretically became nice clean IPA.
But did it work? Well, yes, but it took ages. Honestly I ran
it for about 3 hours and found I was constantly adjusting the temperature to prevent things
getting too hot. In hindsight, a Bunsen burner is not really the way to go – even though
memories of Miss Randall make this special to me.
If I lived in a sunnier climate, a solar still would be safer and more practical. Alternatively
or a more controlled hot plate, might work better too.
But frankly, given the amount of energy, time, possible legality and sheer danger involved,
distilling IPA is not something I’d recommend anyone doing – unless chemistry really is
your thing. By all means filter your IPA in the fashion
I described at the beginning and extend its purchase life. But if and when it stops being
effective, just shop around and get a better deal. It makes much more sense.
So there you go guys. I hope you enjoyed this video. That’s it for now. Take care and
thanks for watching.