In the world of solid imaging with UV-curable stereolithography resins, the management of these chemically reactive systems is often key to avoiding costly machine downtime.

Every vat of stereolithography resin goes through a natural aging process, where the viscosity of the resin slowly increases over time as it is exposed to light. When that light is a well-focused UV laser, the resin cures as desired. When it is stray light, however, unwanted reactions are initiated that lead over time to "viscosity creep." This increased resin viscosity negatively affects build reliability and consistency, costing time and money for end users as well as the resin manufacturers that supply to them.

For this reason, suppliers such as DSM Somos® have begun offering detailed end-user guidance on the proper handling of UV-curable stereolithography materials. Tips such as the following help both novice and experienced end user extend the life of their materials and decrease unwanted downtime.

Perform proper machine maintenance regularly. Many times, as resin begins to thicken, one of the primary culprits is simply dirty mirrors. Dirty mirrors interrupt or distort the laser light so it is no longer focused, and instead floods the entire build chamber with light, causing the resin to react.

Remove crashed builds from your vat as quickly as possible. When debris from a crashed build falls off the platform and slowly sinks to the vat bottom, these pieces of partially cured resin help "activate" surrounding resin.

Consider your build style. Some build styles, such as those used for investment casting, have hollow voids throughout the part that isolate pockets of partially initiated resin from the vat during the build. This resin then drains back into the vat, causing everything to thicken more quickly.

Monitor your refill rates. The rate at which new resin is added affects the level of "fresh" stabilizer circulated through the vat. Don't wait too long to refill and avoid the tendency to store multiple vats containing different materials for significant periods of time.

Stay consistent with your mixing approach. Many users want to know if they should "mix" the resin between builds. If you have been consistent in mixing your resin from the very beginning, when you installed the initial fill, and do it consistently, it is recommended that you keep doing it. If you have NOT been mixing your resin, however, it is NOT recommended to begin doing so. Due to changes in the resin's density as it thickens, resin at the bottom of the vat tends to be thicker than at the top of the vat. Starting to mix it after the vat has already begun its aging process means that thicker resin from the bottom of the vat will start to age the "young" resin located at the top of the vat.