Modulus of Clear Resin

I was wondering if the modulus of a printed part would vary depending on the layer height that you printed with rather than simply being what is shown on the Datasheet. It lists the green and cured states at 1.6 and 2.8 GPa respectively, but is this modulus accurate between 100 and 25 micron layer heights.


FL has a whitepaper

covering the isotropy of the Resin SLA process, which their testing supports.

If a resin part is isotropic at one resolution, I can’t think how it could NOT be at any other resolution, bar extreme cases.


I understand the isotropy of the parts being true. But would the young’s modulus of a print at a higher layer height be a lesser value than that at a lower height?

If SLA isotropy holds true, the final part is an effective homogeneous solid, so if that object was made from 100 layers or 1000 layers it does not change its intensive properties.

However, one thing that may come into play is this assumes that two parts are equally cured, and I suspect (but not tested) that a higher resolution print needs to cure longer than a low resolution print for the same result.

For an uncured part, the modulus would surely be different but we’d have to know the exact laser exposure settings in order to start to guess if it’d by lower or higher. Assuming the Form2 works the same way as the Form1 and 1+, I’m sure the information is available when using OpenFL.

This argument isn’t relevant though as you are supposed to cure the parts in order to meet the mechanical values specified in the TDS. The recommended post-curing settings with the Form Cure are determined to ensure that all of the photopolymerization reactions have occurred, and as such a part should have the same properties after post-curing regardless of the layer height since the very existence of these layers isn’t detectable in the material… but all that is only true if the parts are indeed truly isotropic.