Every LCD/MSLA printer owner runs into this choice at the first resin purchase: water washable resin vs standard resin, the IPA-washed type many listings simply call normal resin. The pitch for water washable sounds like an easy win, rinse a print under the tap and skip the isopropyl alcohol entirely, but the formulation change that makes that possible also changes how the part copes with mistakes after printing, how it handles humidity, and what you’re allowed to pour down a drain. The right pick depends on what you’re printing and how you plan to clean up after it.
The short answer: buy standard, IPA-washed resin for functional parts, hollowed prints and anything that will live in humidity, and buy water washable resin for solid miniatures and small display pieces when you have no ventilated place for a tub of alcohol. Neither type lets you skip gloves, drying, post-curing or proper waste handling.
Detail is rarely the tiebreaker. Water washable formulas such as Siraya Tech Simple are sold as 8K-capable, the same screen class standard resins target. The difference starts when the build plate comes off the printer: which liquid you wash in, how long it takes, how well the cured part tolerates water and solvent, and what is sitting in your wash tub at the end of the week.
Water washable vs standard resin at a glance
| Water washable resin | Standard (normal) resin | |
|---|---|---|
| Wash liquid | Tap water; some labels allow a weak alcohol mix | IPA above 95% |
| Minimum wash, Anycubic Water-Wash Resin 2.0 page | At least 5 min in water, or at least 3 min in 95% IPA | Not covered |
| Station wash cycle, Anycubic wash guide | 10 min small parts, 10–12 min medium and large | 2 min or less small parts, 2–4 min large |
| Overwash failure | Cracking after long soaks; some formulas weakened by alcohol | Surface micro-cracks after 10+ min in IPA |
| Drying before cure | Mandatory, immediately | Mandatory |
| Flammable solvent at home | None required | Liters of IPA |
| Waste liquid | Resin-laden water, not drain-safe | Resin-laden IPA, hazardous waste |
| Hollowed parts | Risky: cavities trap water | Fine with drain holes |
| Gloves for uncured resin | Yes | Yes |
The two Anycubic figures measure different things. The Water-Wash Resin 2.0 product page gives minimums for that one resin: at least 5 minutes in water, or at least 3 minutes in 95% IPA. Anycubic’s wash guide gives station cycles by part size: 2 minutes or less in IPA for small parts and 2–4 minutes for large ones, and in water 10 minutes for small parts and 10–12 minutes for medium and large. The same guide asks for alcohol above 95%, “or the print will turn white after washing and curing.” For how Anycubic’s own resin lines differ from each other, see resin types compared on anycubicguide.com.
What “water washable” actually changes in the resin
Standard photopolymer resin is built from hydrophobic acrylate monomers and oligomers. Uncured resin will not mix with water, which is why it needs an organic solvent that dissolves it, nearly always 90%+ isopropyl alcohol (IPA), to strip liquid resin off a print’s surface before curing. Water washable formulations add surfactants and hydrophilic monomers to the mix so the uncured resin can be emulsified and carried away by plain water instead. Anycubic’s own Water-Wash Resin 2.0 listing states the formula is built specifically to eliminate IPA dependency while keeping tensile strength at 38-43 MPa, hardness at 82-85 HD, and elongation at break at 16-22%, numbers in the same range most hobby-grade standard resins publish. So the mechanical gap between the two categories has narrowed a lot since water washable formulas first showed up, but the chemistry underneath is still fundamentally different, and that difference resurfaces in a few specific places.
Wash workflow: what actually changes at the sink
For standard resin, the routine is a two-stage IPA soak with agitation, typically 2-5 minutes depending on part geometry and resin viscosity, followed by drying time before the part goes under the UV lamp. Split the time across two tanks: a dirty IPA tank strips the bulk resin and a clean tank finishes the surface, so the clean tank stays above 95% concentration for longer. Don’t leave parts soaking while you do something else. Formlabs recommends letting IPA-washed parts dry for at least 30 minutes so residual solvent fully evaporates before post-curing; curing a part while it’s still wet with IPA can trap solvent under the surface and cause cloudiness or weak spots.
Water washable resin swaps the solvent for water but doesn’t remove the workflow. For Water-Wash Resin 2.0, Anycubic’s product page asks for at least 5 minutes in water, and its station cycles run 10–12 minutes for a medium part, followed by a fresh-water rinse and an immediate forced dry. The product page also allows a 3-minute minimum in 95% IPA for that resin, but alcohol is not a safe default for every water washable formula; the strength section below shows why. Follow the label for whatever you buy, because water washable formulas aren’t interchangeable.
Drying is the step most people skip. Siraya Tech’s instructions for Simple say to dry the model immediately after cleaning with a hairdryer. Simple also uses a weak alcohol-water mix rather than plain water, 1 part 90% alcohol to 5 parts water, and Siraya claims a clean part in under 60 seconds. The part still needs to dry completely and still needs a full UV post-cure; skipping either step doesn’t get easier just because the wash liquid came from the tap. For solvent concentrations, dry times, and cure times by resin type, see the full wash-and-cure walkthrough.
Is water washable resin weaker than standard resin?
Not on the spec sheet: the Anycubic figures above sit in the standard-resin range. Where it falls behind is in how it handles mistakes after printing. The hydrophilic chemistry that lets water strip uncured resin also makes the cured part sensitive to long soaks and wet curing, and some formulas are sensitive to alcohol too.
The clearest data comes from dental research. Liu et al. (Scientific Reports, 2024) washed a commercial water-washable crown-and-bridge resin in water, 95% ethanol or a 2% detergent solution for 5 to 30 minutes. Specimens that were only cured, with no wash, reached 110.31 MPa flexural strength. The alcohol group’s mean was 64.30 MPa, while the water and detergent groups kept their properties better and still passed cytotoxicity testing after a 20-minute wash. A dental resin washed in ethanol isn’t a hobby grey washed in IPA, but the lesson carries over: if the bottle says water, wash in water instead of reaching for the IPA tank out of habit.
Standard resin is not immune. Prusa’s CW1 documentation defaults to a 3-minute wash and warns against more than 10 minutes in IPA, because “tiny cracks may appear on the surface of printed objects (even after more than 24 hours).” Both chemistries punish overwashing. They just do it with different liquids.
Where water washable resin loses ground: moisture
The tradeoff that doesn’t show up on a spec sheet is what happens if a water washable part sits wet too long, or has hollow internal cavities that trap wash water. The hydrophilic additives that let the resin dissolve in water also let the cured part absorb a small amount of moisture back. The marketing points at the failure mode: Siraya Tech sells Simple Grey V2 as “not easy to crack due to long-term immersion in water”, and Anycubic sells its 2.0 formula as “resistant to cracking over long periods.” Siraya Tech’s own product notes say an earlier formulation was prone to that cracking, which is why the company reformulated the resin specifically to resist it. In practice the risk is a hollow terrain piece left half-full of wash water overnight, or a mini that went into the curing station while still damp. Dry water washable prints thoroughly (a fan or low-heat hair dryer helps evaporation) and avoid leaving hollow, undrained parts soaking during wash. Standard resin, with no hydrophilic component, doesn’t have this failure mode at all.
Does water washable resin need different print settings?
Yes. Treat it as a new material and recalibrate instead of reusing your standard-resin profile. Anycubic’s starting point for Water-Wash Resin 2.0 is 2–2.5 s per normal layer and 25–40 s for bottom layers. It lists viscosity at 190–230 mPa·s at 25 °C and says the resin stays low-viscosity even at 15–20 °C.
Those ranges are for Anycubic’s machines. Your LCD’s power, the age of the screen and the room temperature all shift the right number. Run an exposure calibration on the first bottle and save it as a separate profile so a later switch back to standard resin doesn’t inherit the wrong values. Anycubic lists a 20–40 °C operating environment. If your garage sits below that, expect adhesion failures and layer separation before you blame the formula.
The disposal difference nobody mentions until it’s a problem
This is the part of the comparison that actually changes your responsibilities as an operator, not just your bottle choice. Waste IPA from standard resin washing is flammable and resin-contaminated, and needs to go to a household hazardous waste program; sun-curing settles the resin out but does not make the solvent safe to bin.
Water washable resin doesn’t remove that obligation, it just changes the liquid. Anycubic’s product page is explicit: “Do not drain wastewater into sewers to avoid contaminating groundwater.” The wash water is full of uncured, partially reactive resin particles, which are toxic to aquatic life and can pass straight through a household water treatment system uncleaned. Let the wash-water container sit in sunlight or under UV for a few days so the suspended resin cures into solid clumps, filter out the solids for disposal as cured plastic, and dispose of the remaining liquid according to local hazardous-waste rules. “Water washable” describes what you clean the print with, not what you’re allowed to do with the runoff.
Rinsing under the tap is a bigger problem than bad etiquette. Many low-cost resins use acryloylmorpholine (ACMO, CAS 5117-12-4) as a monomer. EPA’s significant new use rule for it, 40 CFR 721.5185, sets a release-to-water value of N = 100. Formlabs reads that as 100 ppb and calculates that diluting 1 L of a resin containing 50% ACMO to that level would take about 5 million liters of water. Formlabs sells competing resins, so keep that in mind when reading its framing. But the regulation itself exempts ACMO only once it has “completely reacted (cured),” and that’s the whole case for sun-curing wash water.
The same Formlabs article reports that a large majority of the low-cost general-purpose, high-speed and ABS-like resins it examined contain more than 30% ACMO. So this isn’t only a water-washable problem. Check the SDS of any bottle you buy for that CAS number. The ACMO warnings Formlabs quotes include “May cause an allergic skin reaction,” which is why “water washable” never means gloves are optional. For the full sunlight-cure-and-strain process and how it differs for IPA waste, see the guide to disposing of resin safely.
Which one to buy
Pick water washable resin if you print indoors without strong ventilation, print small volumes where the longer wash doesn’t matter, or you specifically want to cut IPA purchases and the fire-cabinet storage that comes with them. It’s a good match for solid miniatures, small decorative prints, and anyone printing in a garage or spare room where solvent fumes are the real constraint.
Pick standard resin when you need maximum, well-characterized mechanical strength for functional or load-bearing parts, when a part will sit in a humid environment for a long time, or when you already have a solvent recycling or hazardous-waste routine set up and IPA cost isn’t a factor. Standard resin’s higher crosslink density and lack of hydrophilic additives make its published mechanical numbers more predictable over the life of the part.
Choose by what you print, not by how easy the cleanup sounds:
- Solid 28–32 mm miniatures and busts in an apartment: water washable. There’s no cavity to trap water and no IPA vapor in a small room. It pairs well with the compact machines in our miniature printer picks.
- Hollowed statues, helmets and large terrain: standard resin. Drain holes clear IPA quickly, while water left in a cavity dries slowly and is the documented cracking risk.
- Snap-fits, brackets, tool holders: standard resin, or a standard ABS-like resin. A rushed wash is less likely to compromise the part.
- You already run an IPA wash station: stay with standard resin. Water washable resin needs its own water tank, because water carried into your IPA tank dilutes it below 95%.
- A shared space with kids, or nowhere to store flammables: water washable resin, with the same gloves, eye protection and waste routine.
If you’re still putting the setup together, the starter kit checklist lists the tubs, gloves and UV station that both types need.
Either way, the wash step is not the finish line. Both categories still need a full post-cure to reach their rated strength, and both leave you with a contaminated liquid that cannot go down a drain.
FAQ
Can you wash normal resin with water?
No. Standard resin doesn’t mix with water, so a water rinse leaves a film of uncured resin that cures into a tacky, dull skin. Wash it in high-concentration IPA instead. Anycubic specifies alcohol above 95% to avoid white residue after curing. Then dry the part completely before it goes under UV.
Can you pour water washable resin wash water down the drain?
No. Wash water carries uncured resin, and EPA’s ACMO rule stops applying only once the monomer is completely cured. Leave the container in sunlight or under a UV lamp until the resin settles out as solid particles, filter them out as cured plastic, then dispose of the remaining liquid according to local hazardous-waste guidance.
Is water washable resin safer than normal resin?
Only in one narrow way: you no longer store and handle liters of flammable IPA. Uncured water washable resin still needs nitrile gloves and eye protection, and ACMO-based formulas carry warnings such as “May cause an allergic skin reaction.” Read the safety data sheet before buying either type, and handle both the same way.
Can you use a wash and cure station with water washable resin?
Yes. Fill the tank with water instead of IPA and run longer cycles. Anycubic’s wash guide lists 10 minutes for small parts and 10–12 minutes for medium and large parts in its stations. Dry each part immediately after washing, then cure as usual, and keep a separate tank if you also wash standard resin in IPA.
Is water washable resin good for miniatures?
Yes, for solid miniatures it’s a practical choice, especially indoors where you can’t ventilate an IPA tank. Calibrate exposure for each new bottle, dry every mini immediately after washing, and don’t hollow small figures. For hollow display pieces or parts that need snap-fit toughness, standard resin is still the safer pick.
