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How To Make Your Resin Prints Less Brittle

If you are going for a print that has fine details and incredible strength, 3D printing with resin might just be the way to go. However, even with its quality success, it can be challenging to strengthen your resin prints to their utmost durability.

To make your resin prints less brittle:

  1. Reduce contact time with isopropyl alcohol.
  2. Cure the resin prints properly.
  3. Cover the resin with paint or a UV blocker. 
  4. Work in a well-ventilated and warm environment. 
  5. Make your resin print hollow. 
  6. Calibrate printer settings. 
  7. Select a flexible or durable resin. 

Keep reading this article to learn how these steps can help make your resin 3D print more durable. I’ll walk you through each step and give you some pro tips to help you get a long-lasting, durable resin 3D print every time you power up your printer.

1. Reduce Contact Time With Isopropyl Alcohol

One of the disadvantages of resin printing is the tedious post-processing that follows after the actual printing. After you get your print off the bed, you first have to wash it using isopropyl alcohol, which cures the resin and dehydrates it.

Washing is necessary to remove resin leftovers and other particles. You help ensure a smooth, non-sticky, and non-tacky finish by doing so. 

While isopropyl alcohol does a great job washing away uncured resin, submerging your print in the solution for too long can make it more brittle. 

Ideally, your print should only have two to three minutes of contact time with the isopropyl alcohol. Longer than that, the alcohol may worsen the resin’s brittleness. 

There is also a suggested technique to keep the alcohol exposure at a minimum. In this process, you fill two containers with fresh isopropyl alcohol. Then, you dip your print in the first one to remove sticky residue. 

Then, pick up your print and dip it in the other container. Doing so will ensure that the alcohol doesn’t become too saturated with the leftover uncured resin, allowing you to soak your print for less time with good results.

Alternatives to Isopropyl Alcohol Washing

Some users from my favorite 3D printing forum recommend that using alternative washing methods without isopropyl alcohol might also help reduce brittleness. These methods are less reliable than using alcohol, but they can ensure that you never have to deal with an over-cured print. 

My favorite of these methods is to use an ultrasonic cleaner. Water and other all-purpose cleaners are used for this instead of isopropyl alcohol. This water-pick-like device can also clean other things such as jewelry, so getting one may be multi-purpose.

I find that using pressurized water and gentle cleaning solutions is safer for the print, but it doesn’t always get rid of uncured resin as well as alcohol does. So, you might have to spend a while cleaning your model with this method. 

2. Cure the Resin Prints Properly

The curing process is another post-processing step you should not take lightly. This step is essential in hardening the print, and underdoing or overdoing it could lead to fragility. 

Avoid Under Exposure to UV Light or Under-Curing

The interactions between resin and the photons from ultraviolet or UV light make it more solid and durable. Underexposing or under-curing the resin print could make it more fragile because it could not interact long enough with the photons. 

When this happens, your resin print will be gummy, flexible, or very sticky. 

It is important to note that different resin printers and resin types have their optimal exposure times. Thus, you would have to recalibrate your printer every time you make a new resin print with a new liquid resin.

You would also have to be familiar with the optimal settings for the resin you are using. Thus, prior research before undertaking a project would help. 

You may also need to try a few test prints to be more confident with your work. Print a model at different exposure times and see which one has the best quality. Then, be sure to take notes to remember the optimal settings. 

I usually slap a piece of duct tape on my resin bottle and then use a permanent marker to record the optimal exposure times and other settings on the tape. That way, I always know how to set my printer when I pull the resin off the shelf. 

Avoid Overexposure to UV Light or Over-Curing

Too much UV light exposure can make the resin print too rigid and, thus, brittle. Similar to what I have suggested in the previous section, familiarize yourself with the resin’s optimal exposure times.

Also, it would be ideal to work in a room with minimal sunlight. Sunlight is also a UV light source, and working in a space with bright lights or lots of windows could lead to overexposure. 

You may want to work in a garage or put up blackout shades or curtains to control UV light exposure. You can also start the post-processing at night instead to avoid dealing with the sun.

Check out this video from Nerdtronic with details on how you can go into Resin 3D printing.

3. Cover the Resin With Paint or a UV Blocker

Even if you are already done with the curing or other post-processing steps, the resin print may become brittle over time if exposed to sunlight and other UV light sources. To avoid this, you may use paint or a UV blocker to seal your print and keep the resin from further reacting with UV light photons. 

An example of a UV blocker would be the Krylon UV-Resistant Clear Coating (available on amazon.com). It is a spray-type sealant that comes in matte or gloss. It is moisture-resistant and does not yellow over time, which will protect your prints from UV discoloration and that yucky stickiness that can develop over time. 

There are also resin types that come with paint already. You may opt to use them instead, but options may be limited. 

4. Work in a Well-Ventilated and Warm Environment

When working with resin, safety precautions should always be in place, such as working in a well-ventilated environment. Good ventilation keeps fumes from harming you. Still, aside from keeping you safe, it also helps make your resin print more durable.

Too dry and cold environments make the resin prints more rigid and brittle. Thus, avoid working in setups like this and optimize your working station to make it warmer and airier. 

5. Make Your Resin Print Hollow

In resin 3D printing, making the prints hollow instead of solid helps you save your materials because less resin is necessary. However, aside from economic advantages, keeping your models hollow also makes them stronger. It reduces the shrinkage effect and keeps the model from contracting, which will make it less prone to cracking and prevent undercuring in the interior. 

However, if you opt for a hollow design, there may be additional post-processing steps, such as covering the hole where the resin exits and smoothening that surface. 

6. Calibrate Printer Settings

Proper calibration is essential in achieving high-quality and durable resin prints. 

There are standard exposure tests that you can do to calibrate your resin 3D prints. For instance, you can use the XP2 Validation Matrix Model. 

Still, if you’re more hands-on, testing is crucial to get the settings and calibration right. Be sure to play with your printer a bit before printing anything so that you can figure out your printer’s “sweet spot.”

Use the XP2 Validation Matrix Model To Calibrate Exposure Time 

To calibrate exposure time using this model, you will have to print several copies of it at various exposure times. Then, you will compare the prints and see which setting produced the best resin print. 

There are also tell-tale signs for underexposure or over-exposure that you can look for in the XP2 Validation Matrix Model print. For instance, a gap in the middle of the infinity symbol could be a sign of underexposure. If there is a blob instead of an opening, that could also mean over-exposure. 

If the rectangle lines do not appear clean and are imperfect, these may be due to the under or overexposure. 

Anycubic SLA Printers Come With an Exposure Calibration Test

If you just purchased or have an Anycubic SLA printer, you will see that it comes with a Resin Exposure Range Finder (RERF). This is another calibration test to help find the optimal exposure time. 

Like with XP2 Validation Matrix Model, it is also a trial-and-error method where you print several copies using different exposure settings and then determine which produced the best resin print. Aside from standard exposure time, you may also have to set the bottom exposure time. 

The RERF does take up more time and money than the XP2 Validation Matrix Model, so that will have to be a factor you will have to consider. 

Other Calibration Methods

There are also other calibration tests, like AmeraLabs Town, that you can do besides these two to optimize your 3D printer settings. Still, always remember to calibrate before printing every project, if you can, since every resin type and brand is unique. 

Each resin may have properties that impart unique characteristics to a model, but these can only be achieved with proper calibration. 

7. Select a Flexible or Durable Resin

Compared to filament printing, resin printing tends to produce more fragile prints. Still, even though resin tends to be more brittle than filament, not all resins have the same level of fragility. Hence, you would need to choose a more flexible, strong, or durable resin type, depending on the property you aim to achieve. 

Types of Resin

There are many types of resins available. This section will discuss the varieties that will render more strength and make the product less brittle. 

Durable Resin 

This type of resin is comparable to polypropylene (PP). Polypropylene is used to create living hinges, like in flip-top bottles or the lid of a Tic Tac bottle. These materials are suited for products exposed to mechanical stress since they have some flexibility and can resist pressure without breaking apart. 

Durable resin is also part of the engineering resins produced by Formlabs. It resists impact while remaining pliable and smooth. 

Flexible Resin 

Flexible resins are suited for projects where much bending and flexing are needed. You can expect these types of resins to be less brittle since flexible materials need to be manipulated without falling apart. 

An example of a flexible resin would be the Siraya Tech 3D Printer Resin from Amazon.com. This resin will produce a print that is quite flexible yet resistant to high impact. You can mix it with other resins of the same wavelength, so you could mix it with weaker resins to improve durability or flexibility. 

Tough Resin 

On the other hand, tough resin is comparable to ABS, used in filament 3D printing. It is designed to be stiffer and withstand pressure without getting deformed. 

Prusament Tough Resin is an example of a tough resin. It has high resistance to deformation, prints quickly, and can preserve fine details in a 3D printed object. 

Recommended Resin Brands

There are many different resin types available. Still, there are even more brands and specific models produced to suit the demands of various projects. 

I will compile a few recommended less brittle resin brands for this section. Feel free to explore other resin types or brands that better fit you. 

Siraya Tech Blu 

One of the resins mentioned by many resin printing pros and enthusiasts is the Siraya Tech Blu. This resin is precise, flexible, and tough enough to withstand accidental falls without breaking apart. 

Their claim is consistent with the reviews from Reddit and Amazon. It is also consistently part of the top-recommended 3D print resins. 

However, a downside of this item is that it is only for LCD and DLP printers. It can be hard to use and may have an unpleasant smell to some. It may also require a heater. 

Liqcreate Strong-X 

Liqcreate Strong-X is said to be one of the strongest resins in the market. Not only that, it is compatible with a wide variety of resin 3D printers, like SLA and DLP. It also has high-temperature resistance.

A disadvantage of it though is that it is expensive. I could not find it on Amazon.com, but you may access its product page at Liqcreate Strong-X. Still, if you have the money to spend, this is an excellent resin, and it won’t let you down.

Final Thoughts

Resin printing has gained traction for its high-quality output and growing affordability. 3D printing resin makers are also consistently producing better and tougher resins without compromising quality. This is important because the best way to make your resin prints less brittle is to select a tough resin by itself. 

However, besides picking a brand or model of resin, you can also adjust alcohol contact time, curing time, calibration settings, and product design to improve its durability. You may also opt to work in warmer and more airy environments or cover the print with paint and UV blockers.