PU Rigid 650 Resin and PU Rigid 1000 Resin have unique printing and post-processing requirements compared to other Formlabs resins. Formlabs strongly recommends the purchase of additional third-party supplies to ensure printing success with polyurethane resins.

Due to their unique material properties, PU Rigid 650 Resin and PU Rigid 1000 Resin are highly sensitive to moisture. Polyurethane resins start to cure upon exposure to moisture during printing and storing. This causes the resin viscosity to increase until printing is no longer possible. Elevated humidity and temperature accelerate this process.

Formlabs strongly recommends the use of a dry cabinet for improved climate and moisture control while printing and storing PU Rigid 650 Resin and PU Rigid 1000 Resin.

Formlabs recommends Shenzhen Yihexing dry cabinets for a successful PU Rigid Resin workflow. They are manufactured and shipped from China.

If you require a supplier for a dry cabinet that ships from either the US or the EU with a shorter lead time, the McDry MCU-340A dry cabinets from Seika Machinery are an alternative option.

The slow curing times for PU Rigid 650 Resin and PU Rigid 1000 Resin necessitate the use of a humidity cure oven. Moisture is an integral part of the post-curing process that requires an adequate and controlled level of humidity to complete the urethane reaction and make a true polyurethane part.

Even with the use of a humidity cure oven, properly post-curing parts printed in PU Rigid Resins may take more than two weeks. Formlabs strongly recommends the purchase of a third-party humidity cure oven for optimal print success with PU Rigid 650 Resin and PU Rigid 1000 Resin.

The Anova Precision humidity ovens need to be calibrated to achieve the target temperature and humidity. Higher temperatures in the humidity cure oven may lead to a poor surface finish. Before using the humidity oven for the first time, place the temperature and humidity sensor into the humidity cure oven. Adjust the controls as necessary to achieve a reading of 46 ºC & 70% relative humidity (RH) inside the oven.

Parts printed in PU Rigid Resins are highly susceptible to damage before post-curing. Damage can occur when removing parts from the build platform and when removing supports from parts. Formlabs recommends using a stainless steel scraper knife to carefully remove printed parts from the build platform.

PU Rigid 650 Resin and PU Rigid 1000 Resin must be washed with propylene glycol diacetate (PGDA). Polyurethane resins should not be washed with isopropyl alcohol (IPA), which can react with the printed parts and cause degradation in material properties.

After washing, loose parts can be dipped in an n-Butyl acetate bath for no more than 15 seconds to speed up the evaporation of PGDA. Do not leave parts in n-Butyl acetate for more than 30 seconds, as this can cause part warpage. Do not use a Form Wash bucket for the n-Butyl acetate bath, as it has not been tested with high concentrations of the solvent.

Formlabs recommends replacing your PGDA solvent when you start to notice small particles of cured resin remain on your parts after washing. In a Form Wash, this generally begins to occur after several weeks of use.

Filter PU Rigid Resin particles from used PGDA with a strainer to extend the lifespan of your solvent.