Isopropyl Alcohol and 3D print part

[JayW]

I have a question for all you LSP'ers out there who are 3D printing.  Do you find it necessary to uses 99% IPA to clean freshly printed parts, or is 91% adequate?  I ask because 91% is widely available and cheap, while the 99% is hard to find, and expensive.  And while I am at it, does anyone think acetone is best?  Acetone is widely available, but relatively expensive.  

[Rick Griewski]

Acetone is nasty liquid and vapor. It is not a chemical that I would use in

a regular process.  99% vs 91% (rubbing alcohol).  I would read about the particular resin.  I used 91% to clean off some 3D parts without a problem.  My choice is not a part of a production process. 

[Anthony in NZ]

1 hour ago, JayW said:

I have a question for all you LSP'ers out there who are 3D printing.  Do you find it necessary to uses 99% IPA to clean freshly printed parts, or is 91% adequate?  I ask because 91% is widely available and cheap, while the 99% is hard to find, and expensive.  And while I am at it, does anyone think acetone is best?  Acetone is widely available, but relatively expensive.  

Hi Jay, I have used 91% and noticed no difference in performance.  I have even cleaned with lacquer thinner with no issues (I use Elegoo 8K Std Photopolymer resin fyi)

 

But as Rick says, be careful as always....at least be more careful than I tend to be.....

[Juggernut]

I've used 91% isopropyl for awhile now and it does the job just fine as far as I'm concerned.

[LSP_Kevin]

I've switched away from using IPA for the most part, and now mainly use methylated spirits ("metho" here; to Americans it would be known as denatured alcohol). It's far easier to get and cheaper to buy here in Australia, and even does a better job in my opinion.

 

Kev

[BiggTim]

I still use 99% IPA, though 91 seems to work ok. I've been buying it on amazon, and I don't find it to be all that expensive by my measure. Denatured alcohol sounds like a good alternative.

 

Here is the link to my recent order - https://www.amazon.com/gp/product/B08JHBM3VY/ref=sw_img_1?smid=&th=1

Works out to about 20 cents US per ounce after tax.

Edited Wednesday at 08:52 PM by BiggTim

[RCPlym]

No - no benefit at all using acetone on anything really. I only used it as I read a post where someone had used it to produce a genuinely optical quality 3DP lens.

 

I wouldn't use it regularly at all and I use 99.99% IPA as it is very cheap and I need it for the day job, which also requires acetone.

Edited Wednesday at 09:58 PM by RCPlym

[Jim Barry]

I'm a 99% guy. I don't like the cost much, but have not tested against 91% or any other product to compare. 

[Tecnikit]

It’s very simple. I use 99%. But as soon as you put a few parts in the tank and the resin starts mixing with the IPA, the percentage will drop.

 

No one is going to change the IPA after just a couple of washes. The concentration keeps dropping until it stops working effectively.

 

Don't get hung up on exact percentages. If you can buy it at 91%, just use that. The only thing I’d be slightly concerned about is knowing what makes up the remaining 9% when you buy it.

 

Just to know if it’s toxic. I don't understand a 10% difference coming from a chemical company. They do that with 96% alcohol to prevent it from being used as an ingredient in alcoholic beverages. I don't know if that might be the case here. Could be.

 

Javier

 

[wunwinglow]

Plus one for 99%. 3 washes, rough slosh to get the bulk of the resin away, 5 minutes in a 'Bain Marie' arrangement Ultrasonic cleaner. Change the Iso for a clean wash, 5 minutes in the Ultrasound, then a final rinse in essentially fresh Isopropanol, for another 5 minutes. Flick the Iso off, let dry for at least an hour, then a Post Cure UV exposure in a hot air oven at 50C, for another hour.  NEVER EVER put the iso directly in your ultrasonic cleaner! EVER!!!!

 

Your process might be different. I don't care! 25 years of 3d printing, and that is what I do! 😁

 

Oh, quick way to assess the resin 'load' is to watch how quickly the bubbles vanish when you pour the Iso. If they essentially vanish as you pour the liquid, good for the final rinse. The moment bubbles start to hang around for a second or two, move it on to the middle slosh. When the bubbles start to hang around for more than 4 or 5 seconds, move it again to the Rough Slosh stage. This is due to the viscosity of the liquid changing as it carries more and more resin in solution. The pigments and fillers in the resin will settle out, BUT the resin will not, it stays in solution, so eventually will not remove anymore resin from your prints.

 

Disposal? I am still collecting the Rough Stuff until I have enough for an industrial waste disposal company to collect it from me. You can distill it apparently, but since I don't live out in the wilds where a ballooning mushroom of orange flame might go unnoticed, I'll leave that to the professionals!! I gather they use a vacuum distillation process anyway, which sounds fascinating, but..... I have my hobby back now!  No more distractions!!

[SwissFighters]

As far as I'm aware, the difference between the two is only water content (which makes up the remaining 1-9%). 99% will dissolve the resin a little better and dries more rapidly, that's about it. I find it leaves prints that little bit cleaner.
Tony

[RCPlym]

11 hours ago, Tecnikit said:

remaining 9%

 

That'll be water.

 

Also Isopropyl alcohol is definitely not the alcohol to be used in drinks.

[JayW]

11 hours ago, wunwinglow said:

Plus one for 99%. 3 washes, rough slosh to get the bulk of the resin away, 5 minutes in a 'Bain Marie' arrangement Ultrasonic cleaner. Change the Iso for a clean wash, 5 minutes in the Ultrasound, then a final rinse in essentially fresh Isopropanol, for another 5 minutes. Flick the Iso off, let dry for at least an hour, then a Post Cure UV exposure in a hot air oven at 50C, for another hour.  NEVER EVER put the iso directly in your ultrasonic cleaner! EVER!!!!

 

Your process might be different. I don't care! 25 years of 3d printing, and that is what I do! 😁

 

Tim!!!  Great to hear from you after all this time. 

 

Wow what a process!  And I thought my process was tedious!  Here is mine FWIW (for standard gray Elegoo resin) -

 

1.  Take the freshly printed part(s) along with the build plate into the garage on the work bench which has a rubber cover, spray down with 91% ISP thoroughly and repeatedly to get most of the liquid resin off.  This is done in the absence of sunlight as much as possible, so window shades drawn, doors closed, etc.  Or done in the evening.

2.  Pop off the part(s), spray ISP individually, then take part(s) back into the house for a 1.5 to 2 minute wash in the post-curing unit's tank filled with 91% IPA (which has a propeller to mix up the solution).  Occasionally replace the IPA (wen it gets a little cloudy).

3.  Remove parts from IPA tank, take back to the garage and air-dry with a fan.  This can take as little as 10 minutes if weather is hot, or a couple hours if cold and damp.

4.  Once dry, return to the house for post cure in the curing station.  My unit rotates the parts maybe twice per minute of so, for 1.5 to 2 minutes depending on the size of the part(s).     

Edited Thursday at 11:17 AM by JayW

[RCPlym]

'spraying' isoprop? 😬 That brings back memories of scrubbing down pharmaceutical production line machines! 

[Tecnikit]

I didn't say that alcohol was meant for drinking. 🙄 I said that the difference in purity could be the only reason I could think of to prevent unscrupulous people from diverting it for use in beverages. Just as happens with other chemical products. 

 

But if, as some of you have said, it’s water... I get it... I don't think 99% or 91% must be a problem.

 

Each resin has a different chemical composition and may require a different treatment. In my case, I chose my usual resin because of its chemical composition. But I don't think that is the norm.

 

Formlabs supplies a dual IPA tank. The first one removes most of the resin and tends to get very dirty. It’s not worth changing it out frequently as would be a waste of money.

 

The second one stays clearer for the second bath, and the parts come out of it in perfect condition. Of course, the clearer one is nowhere near 99% purity anymore. When the pieces don't come out completely opaque, it’s a sign that the alcohol needs changing—at least the second tank.

 

I usually dump the liquid from the first tank into a drum, move the IPA from the second tank to the first, and then clean the second tank and refill it with fresh IPA. I blow air on it with an airbrush. If residue comes out of the hollows and stains the part, I repeat the bath.

 

To save time, much times I use an airbrush to spray the part with a high-pressure jet of IPA for a wash with pure IPA. Then I use air again to dry it.

 

From there, it goes into a standard box lined with aluminum foil and fitted with a powerful UV tube from an electrical supply store.

 

And after that, it cures in the sun for a few hours. If I have time before shipping, I leave them sitting on a piece of furniture at home, exposed to sunlight for a few days.

 

There are processes for cleaning up the residue. It is a tedious, time-consuming task. But ultimately, the important thing is to avoid throwing away liquid resin. That is also why, as I mentioned, I choose my resin based on its composition. That way, I know exactly what I am disposing of and its safety profile, even when it is dry. 

 

That is why you need to read the manufacturer's instructions and the resin's safety data sheet.

 

As for waste collection companies—at least in my country—they generally only handle pickups starting at the 50-liter drum level.

 

Javier

 

Edited Thursday at 12:34 PM by Tecnikit