Isopropyl Alcohol for 3D Printing: The Complete Guide

Why Is Isopropyl Alcohol Used in Resin 3D Printing?

Isopropyl alcohol (IPA) is used in resin 3D printing to remove the layer of uncured liquid resin that remains on a print after it comes off the build plate. Skip this wash step, and that leftover resin hardens during UV curing — ruining fine details and leaving the surface sticky and misshapen.

When you remove a print from the build plate, it isn't finished yet. After every print on an SLA, LCD, or DLP resin printer, parts come out with an uncured surface layer — which is exactly why an isopropyl alcohol wash is essential. IPA works through straightforward chemistry: it dissolves the methacrylates and acrylic esters that form the base of virtually every resin 3D printing material.

What makes it so useful is its selectivity. IPA interacts with liquid resin and lifts it away from the cured solid without warping or damaging the part underneath. Miss this step and you'll pay for it: any resin trapped in recesses or fine details will cure along with the rest of the print, blurring detail and leaving the piece shapeless. That's why IPA is the go-to product in the post-processing supplies lineup for any resin printing setup.

What IPA Concentration Do You Need: 70%, 96%, or 99%?

For washing resin 3D prints, you need IPA above 95% concentration — ideally 99.9%. The water content in lower concentrations (70% or 96%) reduces solvent power and causes prints to turn white after curing. At 99.9%, IPA cleans faster, dries without residue, and lasts more wash cycles before needing replacement.

The reason is straightforward: resin dissolves in alcohol, not in water. Unlike 70% or 91% IPA, 99.9% contains virtually no water, meaning every drop of liquid is actively dissolving resin. Anycubic states this clearly in their documentation: the alcohol concentration used for washing must exceed 95%, or prints will turn white after washing and curing.

• IPA 70%: formulated for disinfection, not resin cleaning. Too much water — leaves prints cloudy and sticky.
• IPA 96%: acceptable in the short term, but loses effectiveness faster and carries excess moisture.
• IPA 99.9%: the industry standard. Highly effective at removing uncured resin from 3D prints.

That's why we stock Mr Resin 99.9% isopropyl alcohol in our workshop: buying a 5-liter jug for €19.99 is far more cost-effective than small pharmacy bottles, and that extra purity translates directly into more wash cycles before you need to dispose of the fluid.

How to Properly Wash Resin Prints with IPA

To wash a resin print, submerge it in 99.9% IPA for 5–10 minutes, agitate gently, and use a soft brush to clean any recesses. The best approach is a two-bath system: a first pre-wash in dirtier IPA, followed by a final rinse in clean alcohol. Then air-dry or use compressed air before moving on to UV curing.

The basic manual method is cheap and it works: submerge your print in a bath of isopropyl alcohol for 5–10 minutes. Always wear nitrile gloves, since liquid resin is toxic and can cause sensitization. Here are the steps I follow:

1. Remove the part from the build plate with gloves on.
2. Submerge it in a container of isopropyl alcohol and agitate gently to remove uncured resin.
3. Use a soft brush to scrub recesses and areas behind supports.
4. Do a second rinse in clean alcohol. It's recommended to set up 2 baths so you can rinse twice in fresh IPA and confirm no liquid resin remains on the part.
5. Allow parts to air dry, or speed up the process with compressed air.
6. Cure under UV only once the part is completely dry.

There's no need to soak the part indefinitely — a few minutes is all it takes, and leaving it too long can actually soften thin sections.

I'm speaking from experience: the first time I left a miniature soaking for half an hour "just to be safe," the fine details came out half-melted. You gain nothing by over-soaking — it's the opposite of helpful.

How Many Times Can You Reuse the Same IPA?

The same IPA can be reused many times as long as you periodically filter out the cured resin. With normal home use, a single filtered bottle can easily last several months. It's time to replace it when even filtered alcohol stops performing well or has absorbed too much water.

IPA doesn't get "used up" with each wash — it gets dirty. The alcohol used to clean liquid resin prints removes uncured resin residue, but in doing so it becomes contaminated, losing effectiveness and generating waste. The solution is to cure and filter the resin suspended in it. With normal resin 3D printer use, you can get several months out of a single bottle of isopropyl alcohol if you filter the resin as described.

That said, it does need to be retired eventually. Recycled IPA still works, but it may be less pure and its effectiveness can decrease slightly over time. Watch out for water contamination: if water gets into the process, filtering won't remove it — it stays in the IPA and lowers its effectiveness with nothing you can do about it. When you notice that even filtered IPA isn't cleaning well anymore, it's time to replace it.

How to Recycle or Dispose of Resin-Contaminated IPA

To recycle contaminated IPA, expose the dirty alcohol to UV light or sunlight in a clear container: the dissolved resin will cure, harden, and settle to the bottom, where you can filter it out with a coffee filter. The filtered IPA is then ready to use again. Never pour liquid resin or resin-contaminated IPA down the drain.

The trick works because resin cures under UV even when dissolved in alcohol. The resin dissolved in the IPA can be cured and filtered using UV light or sunlight, and the IPA can be reused afterwards. The practical process:

• Fill a clear plastic bottle with your dirty IPA and leave it out in the sun.
• Over time, the cured resin suspended in the alcohol hardens and sinks to the bottom.
• Filter the contents through a coffee filter or fine mesh and set the clean alcohol aside for reuse.
• The resin residue can be disposed of in regular household trash, as long as it is fully cured.

And the golden rule for environmental safety: leftover liquid resin, resin-contaminated IPA, and wash solutions should never be poured down the drain or onto the ground. These liquids can harm aquatic life, contaminate soil, and violate local regulations. Always check your local waste disposal guidelines before final disposal.

Are there alternatives to isopropyl alcohol?

Yes, there are alternatives to IPA, including 90–95% ethanol, dedicated wash solutions (such as Formlabs Resin Wash or TPM), degreaser cleaners, and water-washable resins. That said, IPA remains the industry standard thanks to its balance of affordability, cleaning performance, and fast evaporation.

Here are the options that come up most often in forums and community groups, so you know what to expect from each:

• Ethanol / denatured alcohol: 90–95% ethanol also dissolves resin and has a slightly less harsh smell than IPA, though it tends to cost more.
• Acetone: dissolves resin effectively, but it is aggressive and can leave white marks if you leave the part soaking for too long.
• Dedicated wash solutions: the Formlabs Resin Wash Solution is specifically designed to clean resin prints as efficiently as isopropyl alcohol. Formlabs also recommends TPM for non-biocompatible materials.
• Soap and water: you'll see this suggested here and there, but skip it unless you're using water-washable resin — with standard resin, it won't come close to clearing out all the uncured material hiding in recesses.

The honest verdict: thanks to its ability to dissolve uncured resin and its fast evaporation time, IPA is the go-to choice for cleaning resin prints — and it's affordable and easy to handle with nitrile gloves and proper ventilation. I've tried several alternatives and always end up back with IPA: for 99% of use cases, there's no reason to overcomplicate it.

When should you NOT use IPA — and is water-washable resin a better option?

IPA isn't worth the hassle if you're working in a poorly ventilated space, want to reduce flammability risks, or simply don't want to deal with solvents. In those cases, a water-washable resin is the better choice — it rinses clean under the tap with no alcohol needed. The trade-off is that cleanup needs to be thorough, and mechanical properties are sometimes more limited.

IPA is highly flammable and its vapors can be hazardous, so it should always be used in well-ventilated areas while avoiding direct inhalation. If your printer lives in a small room with no windows, that's exactly where water-washable resins as an alternative shine: they offer the convenience of rinsing directly with water, eliminating the need for chemical solvents like IPA.

That said, it's not a magic fix. Cleanup needs to be thorough, since liquid resin can hide in recesses and cavities if the part isn't handled carefully. And watch what you rinse: the wash water is also contaminated with resin and cannot go down the drain. Bottom line: if you live in a poorly ventilated space or just don't want to deal with solvents, water-washable resin makes your life easier. If you need parts that can take a beating or have complex internal geometries, stick with IPA.

Table: Recommended IPA Concentration by Resin Type

Unless the manufacturer states otherwise, most standard resins wash well with 99.9% IPA. In general, the majority of standard 3D printing resins are soluble in isopropyl alcohol. The table below summarizes the general guidelines by resin family:

The rule of thumb: below 95%, white residue starts appearing and resin cleans up poorly. If you're buying alcohol, go straight for 99.9% and save yourself the headache.

Tips and Gotchas to Avoid Costly Mistakes

A few details that make the difference between a clean print and a wasted afternoon:

• IPA evaporates fast. Keep your container tightly sealed to prevent loss and contamination. A loose lid will reduce your alcohol volume and drop the concentration over time.
• Watch out with FEP and release films. These films are sensitive and can be damaged by IPA — use mild soapy water instead.
• Clean the printer with it powered off. Apply alcohol to sheets and components only when the printer is off, and let it evaporate completely before switching it back on.
• Never power on equipment until the IPA has fully evaporated. With a flammable liquid near a heat source, there's no room for carelessness.

Frequently Asked Questions

Can I use rubbing alcohol (70%) to wash resin?

You can, but you shouldn't. 70% alcohol carries too much water and leaves prints looking chalky white after curing. The concentration needs to be above 95%, or your print will turn white after washing and curing. For reliable results, stick with 99.9%.

How long should I leave the print in the alcohol?

5 to 10 minutes is usually enough. There's no need to soak for hours — excessive soaking can soften thin parts or delicate details. A short wash followed by a final rinse in clean alcohol works better than one long soak.

Does IPA damage already-cured prints?

No. Unlike other solvents, IPA is particularly effective because it doesn't interact with the cured resin. It only attacks uncured liquid resin — which is exactly what you want to remove.

How should I store IPA between uses?

In an airtight, opaque container — or at least one kept away from direct light and heat sources. Since it evaporates so quickly, a loose lid will cause you to lose product and concentration with every opening.

Can I use the same IPA to clean the printer itself?

Yes. Use a soft cloth dampened with 99.9% IPA to wipe down the machine and remove any resin residue. You can keep the more used alcohol for cleaning surfaces and save the fresh batch for the final rinse of your prints.

Now let's get printing! 😎

Mr Resin 99.9% Isopropyl Alcohol – 5 Liters | Resin & FDM 3D Printing

If you print in resin, IPA isn't optional — it's part of the process. Mr Resin's 99.9% isopropyl alcohol gives you a thorough, residue-free wash for your resin prints, and it doubles as a go-to cleaner for your FDM printer too. Grab the 5-liter jug and never run dry in the middle of a project.

€19.99 View in store →