Water Washable Vs Regular Resin — Pros and Cons

Resin 3D printing has revolutionized the way hobbyists and professionals create incredibly detailed and intricate models. From miniatures and jewelry to dental models and functional prototypes, the precision offered by resin (SLA/DLP/LCD) printers is unmatched by FDM technology. However, if you’re new to the world of resin printing, one of the first decisions you’ll face after choosing your printer is what type of resin to use, particularly when it comes to post-processing. The big debate often boils down to: water washable resin vs regular (IPA-soluble) resin. Both have their advantages and disadvantages, impacting everything from print quality and durability to safety and ease of use. Let’s dive deep into the pros and cons of each to help you make an informed decision for your next project. Check out our best 3D printers guide.

What is Resin 3D Printing? A Quick Primer

Before we differentiate between resin types, let’s briefly touch on what resin 3D printing entails. Unlike FDM printers that melt plastic filament, resin printers use a liquid photopolymer resin that cures (hardens) when exposed to a specific wavelength of UV light. This process allows for extremely fine details and smooth surface finishes. After printing, models still have uncured resin on their surface, requiring a cleaning step (washing) and a final curing step (post-curing) to fully harden the print and remove any stickiness.

Popular and affordable resin printers like the Elegoo Mars 4 or Creality Halot-Mage have made this technology accessible to a broader audience, but understanding the accompanying resin types is crucial for a smooth printing experience.

Regular Resin (IPA-Washable): The Tried and True Standard

For a long time, “regular” photopolymer resin was the only option available. These resins require a solvent, typically Isopropyl Alcohol (IPA) with a concentration of 90% or higher, to wash away uncured resin from your prints. After washing, the prints are dried and then post-cured under UV light.

Pros of Regular Resin

• Wider Material Selection: The market for regular resin is vast and mature. This means you’ll find a much wider array of specialized resins, including engineering resins (tough, ABS-like), flexible resins, high-temp resins, castable resins, and specific dental or jewelry resins. If you need very specific material properties for functional parts, regular resin often has more options.
• Potentially Stronger/More Durable: While formulations are constantly improving, many traditional resins are still known for their slightly superior mechanical properties, such as higher tensile strength, impact resistance, or heat deflection, compared to their water-washable counterparts. This can be important for functional prototypes or parts that will undergo stress.
• Established Performance: Because regular resins have been around longer, their characteristics and optimal printing settings are well-documented across many printer models.
• Effective Cleaning: High-concentration IPA is highly effective at dissolving uncured resin, often leading to very clean prints with minimal residue if proper washing techniques are followed.

Cons of Regular Resin

• Requires Isopropyl Alcohol (IPA): This is the biggest drawback.
  • Flammable: IPA is highly flammable, posing a fire risk, especially when stored in large quantities or used in poorly ventilated areas.
  • Strong Fumes: It emits strong, noxious fumes that can be irritating to the respiratory system and eyes. Excellent ventilation is absolutely necessary.
  • Hazardous Waste: Used, resin-contaminated IPA is considered hazardous waste. You cannot pour it down the drain. It often needs to be left in the sun to cure the dissolved resin, filtered, and then disposed of according to local environmental regulations, which can be a hassle.
  • Skin Irritant: Direct skin contact with IPA can cause dryness and irritation. Gloves are non-negotiable.
• More Complex Post-Processing: Handling IPA adds several steps and safety considerations to your post-processing workflow. You might need dedicated wash stations or multiple baths to get prints thoroughly clean.
• Cost of IPA: While reusable, buying and replacing IPA can be an ongoing expense.

Water Washable Resin: Convenience Meets Innovation

Water washable resins are a newer innovation designed to simplify the post-processing workflow. As the name suggests, these resins can be cleaned using plain tap water instead of harsh solvents. They’ve gained significant popularity, especially among hobbyists and those printing in home environments.

Pros of Water Washable Resin

• Ease of Cleaning: This is the standout advantage. Just water! No need for expensive or hazardous IPA. This makes the cleaning process much simpler and less intimidating for beginners.
• Reduced Safety Concerns:
  • Non-Flammable: Water is not flammable, significantly reducing fire risk in your workspace.
  • Less Fumes: While all resins have some odor, water washable resins generally produce fewer and less harsh fumes compared to regular resins, making them more tolerable for indoor use (though good ventilation is still recommended).
  • Safer Handling: While you should still wear gloves and eye protection (uncured resin is an irritant regardless of type), you avoid direct contact with highly irritating and flammable IPA.
• Easier Waste Management (with caveats): Used, resin-contaminated water can, theoretically, be left in the sun to cure the dissolved resin, filtered, and then the hardened resin can be disposed of as solid plastic waste. However, directly pouring resin-contaminated water down the drain is still harmful to the environment and not recommended. Proper curing and filtration are essential.
• Lower Equipment Cost: You might not need a dedicated ultrasonic cleaner or wash station built for IPA, potentially saving on initial setup costs.

Cons of Water Washable Resin

• Potential for “White Residue”: If not thoroughly rinsed and dried before post-curing, water washable resins can sometimes leave a chalky white residue on prints. This is often due to residual water trapping dissolved resin on the surface.
• Can Be More Brittle: Older formulations of water washable resins were notorious for being more brittle than their regular counterparts. While modern formulations have significantly improved, for very thin or delicate parts, or those requiring high impact resistance, regular resins might still offer an edge in durability.
• Less Specialized Options: While the range is rapidly expanding, water washable resins still don’t offer the same breadth of specialized engineering or application-specific properties as regular resins.
• Water Absorption Issues: If prints aren’t completely dry before post-curing, trapped water can interfere with the curing process, leading to a tacky surface or uneven hardening.
• Environmental Consideration (Still): While easier to handle than IPA, disposing of uncured resin-laden water directly into the environment is still irresponsible. Curing the water under UV light and filtering out the solid resin is crucial for proper disposal.

Safety First, Always!

Regardless of whether you choose regular or water washable resin, safety should always be your top priority. Uncured liquid resin, even water washable types, is a skin and respiratory irritant and should not be ingested. Always use:

• Nitrile Gloves: To prevent skin contact.
• Safety Glasses: To protect your eyes from splashes.
• Good Ventilation: To dissipate fumes. An open window and a fan, or a dedicated fume extractor, are highly recommended.
• Proper Disposal: Always cure residual liquid resin (whether in IPA or water) under UV light until it’s solid before disposing of it as regular plastic waste. Never pour liquid resin or contaminated solvents/water down the drain.

Which Resin is Right for You?

The choice between water washable resin and regular resin ultimately depends on your priorities:

• For Beginners or Home Use: If you’re just starting out, prioritize convenience, or print in a shared living space, water washable resin is often the preferred choice. The reduced hazard and simpler cleanup make it much more approachable.
• For Advanced Users or Specific Applications: If you require very specific material properties (e.g., extreme toughness, flexibility, castability), already have a well-ventilated workspace, or need to achieve the absolute highest possible strength for functional parts, regular resins might offer more options.
• Consider Your Printer: While most resin printers can handle both, always check the resin manufacturer’s recommendations for optimal settings. For a fantastic starting point for any resin journey, check out our top recommended 3D printer picks.

Conclusion

Both water washable and regular resins have their place in the 3D printing world. Water washable resins offer unparalleled convenience and reduced hazard, making them ideal for many hobbyists and home users. Regular resins, while requiring more careful handling and hazardous solvents, still offer a wider range of specialized properties and often superior mechanical strength. Whichever you choose, remember to prioritize safety and proper post-processing techniques for the best results. Happy printing!

Ready to explore your resin options or perhaps find the perfect resin printer to start your journey? Visit 3dshopper.com’s dedicated Filaments & Resins section to browse a wide selection and find exactly what you need!