Couple of months ago we got a Form4 and decided to go with Formlabs Resin Washing Solution (further referred to as RWS) over IPA due to concerns over flammability and evaporation losses. When doing my research, I was not fully satisfied with the level of clarity regarding the setup and real, practical considerations. I will share some of my observations during my use of it and hope others can chime in as well!
Currently, I have done about 28 prints (total of 2L printed resin) with washing done in 10L of RWS. 75% of the prints have been with Grey V5, 25% with Tough 2000. With the RWS being fresh, I tried making some Tough 2000 parts with a single-wash setup - 22 mins of washing. However, the parts would frequently get smudges and areas where the residual resin wasnāt washing off. Combined with the long heat-up times of the Cure V1 & price, I swapped over to Grey V5.
My washing process:
To prevent contamination of the build plate so I donāt have to deep-wash it each time, I always pop the parts off and use the basket. For Grey V5 I like to use 12 mins of wash.
Parts are transferred to the basket & water tank from the finish kit.
Parts are submerged for 2-3 minutes and water is only agitate by lifting the basket a few times.
Parts are lifted out of the basket, hooked onto the tank edge and left to drip for a minute.
Parts are transferred to the other tank from the Finish kit, which will catch most of the flying liquid particles. I do recommend using goggles/face shield to prevent the spray from hitting back at you. During the first phase, I just spray over the parts a few times. On the second phase, I use pliers to hold each part by itās raft and then spray it from every angle until it is completely dry. Repeat for each part & cure.
The water shown in the pictures could be satured - I have no way of telling (besides the color) and during my search for answers I didnāt find any helpful guidance. The other trick with RWS is that no hydrometer is included for RWS, which has a different specific gravity than IPA when it is saturated. Even though some suggested hydrometer units are named, I had difficulties with sourcing them. I ended up buying a hydrometer which had the specific required gravity interval, but found out it was too large for use in 10L. Itād be nice if Formlabs could stock the proper hydrometers in their own store to prevent unlucky stories like mine & sourcing challenges.
Additionally, dealing with any sort of special waste such as IPA/RWS leftovers creates a lot of friction for me. If youāre thinking that youāll have half the waste with RWS due to the higher saturation limit, keep in mind the water will balance it out.
Interested in learning more about the experience with RWS of other people. Iām planning to do a few test parts with Tough 1500 V2 soon. The V2 doesnāt require a double-wash setup, so I hope itā'll yield much better parts than Tough 2000.
I appreciate the details you provided. Iāve just ordered some of the Resin Washing Solution to try it out. My reason is to hopefully avoid as much respiratory irritation IPA can cause. We have a ventilation system but I find Iām still sensitive to it in situations where fumes are concentrated.
I hadnāt considered the hydrometer difference. Hopefully we can source something that works.
Iāll post my experience with it once I receive it and test it.
Tried Form Wash for most of 2025 and the positive for me is the lack of evaporation compared to IPA. The rinsing in water after the wash just added another step to my workflow and the parts always still had a film of the washing solution on them. Also, we use Flexible resin which is not compatible with Form Wash so we still have to have IPA tanks available. Prints washed in IPA dry quickly. Another down side to the Form Wash is clean up of the area where it is used because it takes so long to evaporate on its own (wiping down with IPA works well). The work bench and floor tend to get an oily sheen on them, again wiping down with IPA solves this. Handling washed prints with gloves is very slippery and anything the touched with these gloves on becomes slippery too, this is not an issue with IPA and gloves.
Since posting, weāve done some prints with Tough 1500 V2. After doing the post-processing, the parts remain sticky to touch. More often parts will also have regions that appear āshinyā. I believe that Iāve reached the saturation limit by now.
Iāll likely put in fresh RWS and keep working until I run out of our stock. From what Iāve heard, IPA still has the better washing performance, but I have no personal frame of reference.
I believe the folks @ Formlabs Berlin HQ use RWS on all their Wash stations. Maybe someone from there could chime in.
We tried the RWS for the same reason, the first hurdle we needed to overcome was that the parts (and buildplate) stayed āwetā after the wash cycle, where the IPA will evaporate in a short time.
We used water in a spray bottle to clean/rinse the parts after the wash, this worked but the drying of the parts became significantly longer.
In the end we used IPA instead of water to rinse the washed parts, this was more ideal, but it made no sense to keep working like that if you still used IPA in the end.
So right now weāre back on IPA only and Iām quite happy with things as the are,
Weāve collected some workflow tips from the print farm in the Formlabs Budapest office, where Resin Washing Solution has been used continuously:
Remove supports before wash, if the part geometry allows it (thin, flat parts should be left on supports to avoid warping during post-curing).
When doing the water rinse, shake/move the basket constantly instead of only submerging in water, to rinse complex geometries more efficiently. Alternatively, a second Form Wash filled with water can be used.
After water wash, if time allows, parts can be left to air-dry overnight.
If short on time, compressed air/air blow dry can help dry parts faster.
If IPA is available, use IPA in a spray bottle on any āshinyā spots. Then use an air blower. Repeat this a few times until the the parts are clean and dry - and ready to cure.
We hope this is helpful and are always happy to hear more feedback from the community!
Thank you for the points. I find it interesting that point 2 contradicts the usage guide on the support site, which states that no agitation is required.
Is there perhaps updated guidance on the rinse time as well?
How do the Budapest HQ colleagues manage rinsing water and RWS saturation? Are all of these monitored using special hydrometers?
Agitation is not strictly required during the water rinse step, as the purpose of this is simply to remove residue RWS to ensure faster drying, rather than removing liquid resin from parts. However, if a part has a complex geometry that causes RWS to get trapped, then agitating the water can help achieving cleaner parts without resorting to IPA.
As for monitoring the solvent saturation, our team at the Budapest print farm replaces the solvent/water based on the observed wash quality. We know that the hydrometer for RWS not being included is a pain point for a lot of customers, and our team is aware of this issue.
Really interesting insight, love the detailed analysis. I just started using RWS and its loads better in terms of the smell. But we are noticing it is quite tricky to really get all the RWS off the prints post wash. We do a similar step to how you are doing it in the images. We are considering trying out a different workflow and ending it in IPA. Washing in RWS, water soaking / agitation, and then a quick soak and rinse in IPA hopefully get every but of left over resin off. Have you done anything like that?
I have not tried this approach and Iām curious about the results. Maybe it works, but having another container of a different liquid that will also eventually get saturated creates friction to me.
The closest thing to this Iāve tried is washing out holes or other recessed features with a syringe of IPA, but the emerging RWS-water-IPA-resin mixture is so viscous and smudges the rest of the part. I moved over to the approach showed by leonhart88 on blind holes.
You bring a valid point on the smudging. We tried it with some sample parts, and they actually came out quite good. We did notice that you really need to be careful during the wash process as they are really easy to scratch and smudge (as mentioned). But after curing and letting them sit for 15-20 minutes they were very nice. We are constantly playing around with post processing techniques to get the best parts possible. Thanks for the insight! And yes, leonhart88 has a pretty go remedy to help!
Just to share our processā¦We have the Wash L filled with TPM, afterwards, we rinse in soapy water, then quick dip in clean water. final wipe down with IPA so it dries fast.
The company I work for recently purchased a 4L printer and we use the Resin Washing solution. Iāve experienced the same issues with the solution and am happy that Iām not the only one. One question I had since you are discussing work flows is if you cure the part when the part is still a little tacky or if you let it dry completely. I only ask because with the resin washing solution I canāt seem to get rid of that tacky feeling.
The only tackiness I had experienced on parts after curing was with Tough 1500 V2 and with possibly saturated RWS/washing water, which I thought could be the culprit. We still use some of these parts and the tackiness has disappeared over time. I donāt think I can provide a helpful answer here.
An update to this thread from my side is that weāve now switched to using IPA as an experiment. Itās too early to give objective updates on performance right now.
I operate a 4L and a 4, we use 12 different resins. I was also disappointed when we bought a new Wash L to start using RWS and then I discovered that we would need to also add an additional water wash basin for rinsing. Think I might try to skip the water and just rinse in IPA.
That said my process is:
10-minute cycle in the Wash L with RWS
30-60 seconds swishing in the water bath
1ā5-minute cycle in a small wash with 99% IPA. Depending on resin type.
leave these parts to air dry, on a mesh drying rack under a small fan for as long as I can before curing or handing off if a cure is not needed. I have found overnight is best case scenario, have not tried compressed air.
I generally get really good results with this process, IPA freshness helps. It lowers the amount of standing and waste IPA. The 10 gallons of RWS has lasted most of 1 year and I am just about to replace the saturated RWS with fresh for the first time. I do change the water bath a couple times a year.
Hi everybody, Iām happy to share that with the latest firmware update for the Form Wash L, the device now supports Formlabs Resin Washing Solution, so when RWS is selected, the solvent monitor will measure the. saturation of the solvent. See the release notes here, and instructions on updating the firmware here. We hope this will be a useful workflow improvement for a lot of you!
