Resin 3D printing produces high-quality, intricate prints with smooth surfaces and crisp details. However, fresh off the print bed, resin models are delicate and require further curing to reach full strength. Knowing the ideal curing times is key to getting durable parts that retain fine features. Follow these resin curing best practices for stunning prints.
Initial Curing Prepares Prints for Handling
Once removed from the printer, resin prints are not fully cured and need some initial processing before handling. Parts are rinsed in isopropyl alcohol to remove any uncured resin. The wash also prepares the surface for optimal curing by removing the sticky inhibition layer.
Prints then undergo an initial UV cure, either in a wash and cure station or LED curing box. Cure times range from 2-10 minutes depending on the resin properties. This stabilizes the model enough for handling without damage. It’s just the first step in fully curing the print though.
Primary Curing Hardens and Strengthens the Resin
After the print is cleaned and stable, it’s ready for the primary UV cure. This is a longer exposure under UV light to fully polymerize the resin. Primary curing takes 30 minutes up to a few hours depending on resin chemistry.
Prints cured for shorter times will be fairly strong but have a tacky surface. Longer cure times between 1-4 hours ensure the resin reaches maximum hardness. The optimal time depends on factors like resin type, print size, orientation, and number of prints curing together.
Settings on the higher end, around 4 hours, are ideal for functional prints that need the highest strength and heat resistance. Miniatures and decorative models don’t require as long of a cure. Dialing in the right time takes experimentation to find the shortest duration for full curing.
Secondary Curing Enhances Heat Resistance
Functional resin prints subject to higher temperatures benefit from a secondary UV cure. This is an additional extended exposure under UV light from 4-24 hours.
Secondary curing further hardens the resin to withstand heating up to over 100°C without losing strength or shape. It improves heat deflection temperatures by up to 15°C. This makes cured resin much more thermally stable.
Prints intended for outdoor use also need enhanced UV resistance from a lengthy secondary cure. It helps stabilize the material against color change or degradation over time from sun exposure.
Consider Resin Properties for Cure Time Needs
Not all resins require the same exact curing times or processes. Resin properties determine optimal durations and methods.
- Standard Resins – Require 1-4 hours initial curing for full strength. Addition secondary curing boosts heat resistance.
- Fast-Curing Resins – Only need 30-90 minutes initial curing. Great for high throughput. Secondary curing still improves thermal stability.
- Durable/Engineering Resins – Need full 2-6 hour initial cure plus 8-24 hour secondary curing for maximum physical properties.
- Heat Resistant Resins – Require long 6-12 hour initial cure and 24 hour secondary cure to maximize heat deflection temp.
- Flexible Resins – Cure times tuned for elasticity; low initial cure time preserves flexibility.
Consult manufacturer guidelines and experimentation to dial in perfect times for each resin’s characteristics.
Curing Methods: UV Light Sources
UV light provides the energy for photocurable resins to solidify. Different light sources have pros and cons for curing prints.
- LED Curing Units – Affordable and compact. Limited size means prints cure in batches.
- UV Flood Curing Chambers – Large capacity, fast batch curing. Units are costly though.
- Cure & Wash Stations – Convenient all-in-one cleaning and curing. Small builds only.
- Sunlight – Free but inconsistent exposure; longer cure times needed.
A wash and cure station or LED curing unit works great for most small prints. Larger prints benefit from a UV curing chamber that can accommodate them.
Curing Tips for Superior Print Quality
Follow these guidelines when curing prints for best results:
- Cure prints as soon as possible after printing, within 6 hours.
- Clean prints thoroughly before curing to remove uncured resin.
- Use enough supports and orient prints to minimize deformation during curing.
- Cure prints with light source as close as possible without touching.
- Cure prints in short batches if needed to avoid overcrowding.
- Use turntables or regularly rotate prints for even curing.
- Check prints regularly so you can stop curing immediately once hardened.
- Wear gloves when handling and avoid direct skin contact until fully cured.
Proper curing improves print strength while retaining fine details. Take the time to optimize the process for your application and resin type.
Signs of Insufficient Curing
Undertreated prints exhibit flaws from uncured resin:
- Sticky/tacky surface
- Flexible when should be rigid
- Distortion or drooping
- White uncured resin trapped inside
- Brittle areas and cracks
- Reduced stability at higher temperatures
Increase cure times or try secondary curing if prints show these issues.
Signs of Overcuring
It is possible to overdo curing, especially with prolonged exposure after full hardening:
- Yellowing of light resin colors
- Loss of fine details and resolution
- Embrittlement and cracking
- Increased fragility
- Deformation from excessive heating
Adjust curing times down if prints show degraded quality from overtreatment.
Achieving Optimal Resin Curing
Dialing in the perfect curing routine takes experimentation with times and techniques. Keep track of results for each resin and print geometry. Thorough curing ensures prints have maximum structural integrity while avoiding the defects of under or overtreating. Parts with the right curing regimen will have superb resolution, vibrant colors, and outstanding performance.
