Introduction: Platypus Water Bottle SLA 3D Print Wash Station

About: Welcome to my Instructables channel where I'll share my wacky and unique creations that hopefully others find useful, or better yet, inspire an evolution of even better ideas!

Without access to Iso-Propyl Alcohol (IPA), due to COVID-19, the 3D printing community has been on a hunt for alternative solvents and cleaning methods for their SLA 3D printing.

If you're reading this Instructable you probably have an understanding of SLA 3D printing, but in case not, here's a quick overview:

  • SLA printers use a bath of liquid resin that is UV light-cured, usually via laser. When the prints are completed, they are coated in the uncured resin they were created from.
  • At completion they are left on the build platform to drip off as much of the resin as possible, because the resin is very expensive (top right image above)
  • Once dripping has stopped, they are removed from the build platform and put into a bath of IPA (90% strength or greater) for 15 minutes or more. The IPA is either still or can be agitated like in the Formlabs Formwash.
  • This "Wash" removes the uncured resin, and allows the part to be sent onto the final post cure, which is a combination of heat (around 150°F) and additional UV light. Like in my DIY cure station.

Back to the current issue of IPA not being available. This is mainly due to the fact that it is the primary ingredient in alcohol-based hand cleaners and other sanitizers, so it is virtually impossible to get. And if you can find any for sale, it will not be at the normal $1 per quart price. If it is reasonably priced, be highly suspicious that's its not real or at the very least a lower strength like 70% IPA being mislabeled as 90% or higher.

I have tried most of the suggested alternative solvents/cleaners/degreasers (there are many, and the closest runner up was Mean Green). But the hands down winners are Acetone and Denatured Alcohol, they are both equivalent to if not better than IPA.

However, both Acetone and Denatured Alcohol costing $10 per quart, they need to be used more expeditiously. So I came up with this method with a little help from NASA!

SAFETY NOTICE: I'm not going to quote MSDS sheets, flammable volatility levels, or flash points. You can find all that online. But do be aware these are flammable liquids and give off vapors, so do NOT use these indoors, but ONLY in well ventilated spaces. Treat Acetone and Denatured Alcohol as you would IPA, but with a few degrees more caution. Wash your hands, don't get it in your eyes, etc.. OK, done with the lawyerey stuff, let's get on with the fun.


Step 1: Get Yourself a Platypus

They have many different colors and patterns. But this one had the clearest pouch to see inside. That's the only reason I chose it.

Step 2: Destroy the Platypus

Well, at least for being a water bottle any longer.

  1. Open the drinking lid and blow air inside to inflate the bottle some. Then close the drinking lid while trying to keep as much air inside as possible.
  2. Flip the bottle over. On the bottom you can see a very subtle crease line in the plastic (highlighted with the yellow dashed line in the second image above).
  3. Use a very sharp knife or razor blade to cut along that line, starting in the middle
  4. Don't use the blade to cut all the way to each side. Instead, cut to about 1/2" to 1/4" from the sides and then just tear it the final amount by pulling the cut edge apart. That way you don't risk cutting into the sidewall of the bottle.
  5. Once you make that cut and the bottom of the bottle is fully opened - STOP! If you're like me, you'll be tempted to cut away the two flaps left behind. If you do, you again risk cutting the bottle where you don't want it cut. Also, I think leaving that material behind allows for a better seal later on.
  6. Put away the tools, that's all there is to it

Step 3: Gooey Part Takes a Bath

  1. Place the part inside the Platypus through the large opening we made previously
  2. Turn the Platypus upright and fill with your solvent of choice so the part is about half submerged
  3. Fold the large opening side at least 3 times (about 1/2" size folds)
  4. Secure the folds with a wide binder clip like I show in the supplies section, or a few spring clamps, or some PVC clamps like these from graydog111 - DIY PVC Clamp

An unexpected Huge Bonus I discovered with this method:

  1. I'll place my build platform so the newly printed part is pointing up and still fully adhered to the build platform (Second image above)
  2. Then take the Platypus bottle, and drop it over each of the parts. Now you can grip the part, but through the Platypus, thus keeping your hands clean.
  3. With the Platypus over the part and held in place, you can then use your putty knife or pry tool to separate the print from the build platform, and then simply flip the Platypus back over and you're ready to seal the end.
  4. Huge Bonus - you may be wondering, what is it? Well, this method prevents the part from flying across the room or crashing to the floor as it inevitably does when it POPS off the build platform when you least expect it to.

NOTE: The yellow part is from another project I'm working on. I just used it to simulate a 3D printed part. It is actually a float from this company Jobe Valves.

Step 4: Gooey Part Gets Dunked

  1. With the large opening closed and sealed, flip the Platypus over
  2. Open the drinking lid and squeeze the bottle so that all the air is expelled and the part(s) are fully submerged in the liquid
  3. Close the drinking lid

Step 5: NASA's Contribution

This step is optional, but for the investment of $90, believe me, you will never go back to the old soak and wait method.

  1. Fill the ultrasonic cleaner with regular tap water (I found the heater doesn't really improve anything, so I leave it off.)
  2. Drop the Platypus into the ultrasonic cleaner and run for 3 minutes. Its OK if its not fully submerged as the sound energy will travel through the water and into the solvent; even the portion that's above the water line.
  3. Remove the Platypus from the ultrasonic cleaner

This ultrasonic cleaner works great, but I had these concerns:

  • It has a built in heater, so initially I was concerned with putting any of the solvents into it even though the heater is manually controlled
    CAUTION: Solvent + Heat = Fire
  • I also didn't want to fill it full with solvent (remember the $10 per quart price?)
  • It doesn't have a drain or easy way to empty whatever liquid you put in it

During my research into IPA alternatives I came across a Reddit thread that mentioned the NASA paper attached above. I had already tried Ziplok bags but didn't have good results. So after finding the NASA paper and realizing they had come up with the idea more than 50 years ago I thought I'd keep at it.

I knew the key was a flexible but robust container. That's when I thought about the large bladders inside CamelBaks. I have a couple and thought about sacrificing one in the name of science, but after thinking about how it would be difficult to get the part inside cleanly and then how to bleed off the air, I held off on trying it in hopes of finding a better solution. And I did...

I remembered taking our friends in Singapore some Platypus water bottles on a business trip many years ago, because at the time they were not available there (or maybe they were just really expensive, I don't recall). I thought I had found the solution so I ordered a few without really looking at them and once they arrived I realized they don't have a large opening similar to the Camelbak bladders for filling. But since I had already bought a few I went ahead and tried cutting them open and then resealing with several folds and clamping the layers of folds together.

And it works GREAT!

It doesn't leak any solvent at all!

Step 6: Decant

  1. After the ultrasonic treatment, decant half of the solvent into an appropriate container for suitable disposal or for the frugal ones save it for other uses, or it can also be treated for reuse*
  2. Close the drinking lid, but don't open the other end just yet

*Leave the container undisturbed to allow the heavier liquids to settle to the bottom (usually overnight is sufficient). Decant very slowly the cleaner and clearer liquid that will rise to the surface. Another method, which I haven't tried is placing the container in sunlight so the dissolved resin cures and the clean and clear liquid on top is even easier to decant.

Step 7: Shake Shake, Shake Shake, Shake It!

Now I got that song in my head.....(Shake It, by Metro Station)

Just 10 seconds or so is fine. Remember, the solvent is still there eating away at the plastic of your part. Both Acetone, and Denatured Alcohol are much stronger than 90% IPA. Where you can occasionally forget about a part and leave it in IPA with no ill effects. Leave a part in this stuff it won't be there when you return.

My rule is to not let the parts be in contact with the solvent for more than 10 minutes total and it has worked so far (about 7 prints using this method).

NOTE: If you choose not to do the ultrasonic cleaner step, skip step 4-6. I haven't tried using either of these solvents without the ultrasonic cleaner. But if I did I would try this:

  1. Fill halfway and don't bleed the air out
  2. Let soak for 5 minutes while turning the Platypus over to keep all sides of the part(s) wet
  3. Shake for 2 minutes
  4. Decant some of the liquid
  5. Let soak again for 2 minutes
  6. Shake 1 minute
  7. Fully drain

Step 8: Drain the Bathtub

Fully drain the Platypus into the same appropriate container.

Step 9: Finish

  1. Remove the clamps
  2. Unfold the folds
  3. Remove your part
  4. Rinse the Platypus with hot water and set aside to dry for the next use

Thanks for taking the time to read through my Instructable, and please let me know if anyone has any questions. I try to respond to every comment/question I get. Stay safe and healthy! And happy printing!

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