Post Production cleaning

[Davidwedge]

I noticed a post asking about the resin wash solution, and thought this would be a good point to add in regarding cleaning.

Several months ago we were working with the guys at Formlabs (prior to the resin wash solution coming out), and they were kind enough to provide a Wash II for us to use in testing. I should publicly apologize to them for not getting back sooner (i had my reasons - see below).

We had been (Q2 of this year) working with ultrasonic quite a bit, but in addition using SimpleGreen (concentrated). I’ll outline a handful of the paths we ran in our testing, and give some feedback as well

Due to being a victim of a pretty bad car wreck, my own writeup of our testing got terribly sidelined for the fall, and I’ve been well enough to have picked it up again around a few weeks ago.

Now, we’ve only run ~ 25 liters of resin thru our Form4 this year, so I wouldn’t claim to be an expert on it by any stretch… This has been across: Black, Grey, various Silicons, and Tough2k.
This testing has been over the course of producing somewhere around 2200-2500 various prototype and production components… approx 20% of these parts have been smaller than 1 cubic inch, about 60% have been the range of .5" x 1"x 2",and the remainder have been a bit larger - say 2"x2"x3 ish… So a good smattering of options. 80% + of the units have logos, lettering, or other high-visibility surface engravement on/in the surface, which makes for excellent test subjects…

So… We had several goals in this process:

1. Get away from any brushing or cleaning work. With the exception of one or two above, we never actually brush or clean any production parts post-print. We simply move them into the next container and let the tools do the cleaning. No brushing, no scraping, etc… in fact, the only real handling we do is breaking parts off of the build supports… And we’ve gone to miniscule support brackets (.15-.25 mm), so there is virtually no cleanup of parts post cure (obviously your mileage may vary, considering product dimensions and material strength)…
2. Cut down on waste of IPA. yes, it’s cheap/cheaper, but there is a non-zero ecological impact, and we really wanted to cut this down… It really adds up when you start doing small runs of prototyping. We found that the general IPA life was too short, and the eco foot print was larger than we liked.
3. Consumables loss. We wanted an intermediate solution which could be recaptured, and cut down both ecological and logistics…
4. Time savings.

So…
Our testing paths:

Control path:

• hand clean/wipe resin off
• wash in IPA Wash 1 (10 minutes)
• cure

Alternate test paths
1. Simple Soak

• soak in Simple Green (10-20 minutes)
• wash in IPA (10 minutes)
• cure

2 Long SimpleSoak

• soak overnight in Simple Green (8-12hrs)
• wash in IPA (10 minutes)
• cure

3 Simple Wash 1

• wash in Simple Green (in FormWash version 1) - (30-40 minutes)
• splash thru IPA bath to remove SimpleGreen
• wash in IPA (10 minutes) in Wash 1
• cure

4 Soak & Wash 1

• soak in Simple Green 10 minutes)
• wash in Simple Green (in FormWash version 2) - (20 minutes)
• splash thru IPA bath to remove SimpleGreen
• wash in IPA in Wash 1 (10 minutes)
• cure

5 Soak & Hot Ultra SimpleWash

• Ultrasonic/heated to 40C in Simple Green 10 minutes)
• splash thru IPA bath to remove SimpleGreen
• wash in IPA Wash 2 (10 minutes)
• cure

6 Soak & Warm Ultra SimpleWash

• Ultrasonic/heated to 30C in Simple Green 10 minutes)
• splash thru IPA bath to remove SimpleGreen
• wash in IPA Wash 2 (10 minutes)
• cure

7 Soak & cold Ultra SimpleWash

• Ultrasonic/no heat in Simple Green 10 minutes)
• splash thru IPA bath to remove SimpleGreen
• wash in IPA Wash 2 (10 minutes)
• cure

8 Soak & Wash 2

• soak in Simple Green 5-10 minutes)
• wash in Simple Green (in FormWash version 1) - (20 minutes)
• splash thru IPA bath to remove SimpleGreen
• wash in IPA Wash 2 (10 minutes)
• cure

SO, results.
First, the control path is the most simple. It has all the negatives and few of the positives.
Now in their defense, this wash process was with a Wash 1, which is significantly lower performant than a Wash 2. I know - we have Wash 1 and Wash 2 side-by-side, and the difference is visibly obvious, due to the waves and intensive motion induced in the Wash2.

However, using a Wash2 alone would not solve for any of the various other goals.

On Ultrasonic. - - - Hot Ultrasonic (#5 above).
40C is too hot. the product comes out soft. too soft. we figured out that we’ve likely been causing changes to the plastic at that temp… So while the product came out clean, the product was likely altered (not visibly, but likely altered to be weaker).

#6 (Ultrasonic and wash)… 30C is ok, though we really didn’t see any significant cleaning difference from the room temp SimpleGreen Wash (#8). In fact, the heat doesn’t seem to help remove/loosen the resin in any noticeable level from our testing.

Conclusions:

1. The Wash 2 rocks. It really IS JUST THAT GOOD. Quite a significant improvement over the 1. quicherbitchin and go buy one. or, I’d say buy 2 (see below)…
2. Ultrasonic isn’t really useful, if you are running the Wash2. The real need is to have good agitation… the ultrasonic action is an acceptable displacement engine, but the wash is long-term more effective in my opinion.
3. We have only ONE of the Wash2, but if we had a second, I think we would have 100% perfect products, nearly every single time. In fact, as it currently stands, using paths #4, 7, or 8, we’ve lost fewer than 5 production/prototype units due to incomplete cleaning in the post-production processes. So that’s greater than 99% effective cleaning for acceptable outcomes… I’m not displeased…
4. SimpleGreen is your friend. 2.5gallons Concentrate is $22 at Lowes… and it cleans up easily… Now, I’ve not tried the resin wash solution, but I’m going to step out on a limb and say there’s no way it can match SimpleGreen for cost and usable life. SimpleGreen (SG) is nearly permanent… in fact, we bought 5 gallons, over 7 months and 2000 parts ago, and are still using it… and likely have over 4.5gallons of it left…
   Our steps with SG is simple: The resin tends to fall to the bottom,and if left dormant, will separate to the bottom… We let it settle over the weekend, then pour it thru a metal sieve to capture the majority of the resin out of it, and pour it back in the wash tank… Then every 2-3 months, we pour it back into the original SG 2.5 gallon containers, let it settle again overnight, then set it on the dock for a day… This causes further separation, and the resin hardens into a sludge at the bottom, for easy separation.
   I’m not saying SG has eternal life…but well, it’s well past several DOZEN liters worth of resin in production at this point, and is super effective. and it’s $10/gallon…

Finally, we also bought a $120 whiskey still off of Amazon, and we use it to recover 90%+ of our IPA… We never toss IPA, and because of our use of SG, we only have to clean and recycle the IPA every 3-4 months. It has quite a significant impact on the life/longevity of the IPA.
The distillation of the IPA is pretty simple - though it takes about 4 hours to run… So you really do need to either have enough IPA to have a run batch and a batch to clean, or you need to have shut down production for a day or so while running the distillation process…

SO…

Which path is most effective?

#8 and #4 above. These are the 2 most effective and least complicated (both in time and hassle)… And they happen to be the less expensive as well…

If I had my way, we’d have TWO of the Wash2 units, no ultrasonic tank, and a couple of the Form4 Finish Kit buckets for ‘splashing’ thru…

Our process is usually most effective when we ‘splash’ the initial units thru a bucket of SG, which gets ~50% of the resin off (thereby doing the most concentrated initial cleaning, THEN the SG Wash2, THEN a splash thru an IPA bucket (to get most of the SG off the product, THEN the IPA wash in a Wash2.

Would love to get some feedback or questions…

[figure1a]

Thanks for all the research/info. My own experience with any of the green solutions is that they tint clear resin slightly green but other than that cleans pretty much perfectly.

Trying the FL RWS today for the first time.

[figure1a]

Did the FL RWS today and my clear resin came out greenish again. So, I don’t think the green solutions were turning my clear resin prints green. I think clear resign just comes out of the wash greenish and then the green tint fades a bit over the next few days as I put this new print next to one from last week and the one from last week looks nearly clear now. I think I will go back to the green solutions as the FL RWS stinks and is very expensive.

[Davidwedge]

Our primary resins are the Grey and Black (V5), but we’ve done a couple liters of flexibles as well…

I’ve never seen any greenish tint post-production, so I can’t speak to that.

[verdugod]

Awesome overview @Davidwedge thanks so much for taking the time to share your insights with us!

[jamesp]

This is super helpful. I’d love to hear about your experience with using a cheap still for IPA recovery. I’ve looked into industrial systems to do it but the price has a few more zeros on it.

[Tommy1]

For a while I was placing parts in SG ultrasonic before a wash bucket of IPA. I stopped using the SG because I felt like once it filled with resin it was just transferred to the IPA bucket. It seemed to have a shorter life than the IPA because it filled with so much debris. I never tried curing and sifting the resin. Good to know about the Wash 2, and I think I might try to give SG another try.

[Davidwedge]

The entire IPA recovery system we run is easily less than $500…
• There are a bunch of $90-150 stills from Amazon.
• an automated chiller (from ebay or AMZ) is $200-400
• distilled water (for running in the chiller) is less than $20
• an inductive heating plate is $75-100 on AMZ

First, the still…

• size matters. I’d probably choose a 3 gallon or smaller, and run my recovery in smaller batches… my original is a 5 gallon, and it’s both big, ungainly, and takes FOREVER to come to temp… a 2-4 gallon would be better, though it would also limit your recovery batch size a bit.

• HOW you cool is super important, as it’ll dramatically change how quickly/well your still operates… I happen to have access to a handful of laser deck chillers like this:
  

  

These are super easy to run, fairly affordable ($300-500 on ebay/amz), and they can be programmed to run super cold, which speeds up the conversion… i config’d one to chill at 5C, and it does great.

IF you run a chiller like this, you need a closed evap pot style still, vs the conventional open pot… it’s important, as the chiller water really needs to stay pressurized all the time for flow management.

• Standard 3gallon still from amz… Amazon.com: VEVOR Alcohol Still 3Gal/12L Alcohol Distiller Stainless Steel Distillery Kit for Alcohol With Copper Tube Home Brewing Kit Build-in Thermometer for DIY Whisky Wine Brandy : Home & Kitchen

Some stills include a Thumper, which can also be used as well for the evap process (depending on the version).
You CAN get one with a thumper as well, but this complicates things a bit more… You’re likely bringing some water vapor in, have to do better temp management, etc… i’m not a huge fan for this application…

• here’s the ‘wiring’ for the process…

you simply pour your ‘old’ IPA into the pot, close/seal it, put it on your burner, fire it up, and hook up the hoses as shown…
turn the chiller on to keep the copper pipes cold while in recovery, and run a tube from the output into a small bottle for your clean/fresh IPA…

• lots of people who, errr - “experiment with alcoholic distillation” - well, they often just use ice water instead of a powered chiller (which is actually very little more than a refrigerator with a water pump)… I’m more of an automation guy and since I don’t have an ice machine handy (and I do have a handful of these chillers sitting around), have gone the automation route…

• The only other thing needed is a heat source… Back in the day, people put it over a fire in the woods… but since we’re not worried about the revenuers (g-men as they called 'em), I would generally use an electric burner or an induction burner…

the resistive/electric burner is cheaper, but heats a bit more slowly, and isn’t quite as accurate (if that matters to you)…

If I were doing it again right now, I’d get a 3 gallon still from ebay for ~ $60, figure out how to modify the reduction pot to have a watertight lid, an induction plate for ~$60,and a $300 chiller off of ebay.

For our uses, the still pays for itself 1-2 x/year… your mileage may vary…
oh, and don’t get the bright idea to use this still for doing your own moonshine on the weekend - the toxins from the resin WILL render this too dangerous for human uses…

[jamesp]

Thanks so much for this. I’m definitely going to be setting this up. I generate enough waste to pay Safety Kleen, but not enough to do real automated reclamation. This is perfect.

[Davidwedge]

There are 2 quick ways to lengthen your SG life.

1. sift it thru a large sieve… I’ve used the old fashioned metal strainers (metal sieve), but have just ordered a set of silicone plastic ones from Amazon, and will try those shortly… The primary issue with the metal sieves is that they tend to clog up with blobs of resin, and if you make the mistake of doing the work outside, your sieve is ‘permanently converted’ into a container instead of a sieve… Don’t ask me how I know…
2. IF you sift the SG, that is going to remove/reduce the majority of the resin. Then every few weeks/months, we pour the SG back into the original SG container, let it sit still for a few days (to settle fully), then carefully take it outside into direct sunlight. This hardens the resin into a thick blob, which can then be easily separated (just pour 90% of the SG off the top, then scrape out the blob and sift the remainder…

We’ve never actually replaced our SG, despite thousands of parts going thru it. I’d suggest that with a good maintenance process, SG will last for years…

[Tommy1]

David,

Thanks for getting back to me. This is good to know, I’m going to give SG another try.

[Davidwedge]

A quick update on this…

The plastic/silicone strainers from Amazon are entirely ineffective and don’t really strain properly…
The only solution we’ve had on that is to line them with paper towels, pour the SG thru that, and then swap out paper towels every gallon or 2… It works fine that way - not perfect, but functional…

I’ve also sourced some of the old timey metal sieves, and will give them a go shortly…

I should note an additional thing we’ve uncovered.

IF one’s SG is too far contaminated (ie, the resin hasn’t been strained out/hardened out recently), products left in for extended periods will begin to get a lighter staining on them - presumably this is a combo of loose resin and SG mixed (the stain can be construed as ‘light green’ or a ‘greenish haze’…

The solution: Either leave products soaking less than 90 minutes, OR clean/replace SG…

[henryqiu]

Love this thread! Thanks for the detailed insights, I’ve been meaning to find a simple DIY IPA distillation setup for my personal workshop.