Resin parts cracking days later, could this be trapped resin or over curing?

[AcesClaudel]

Has anyone had a resin print that looks perfect, feels solid, and then cracks later like it’s aging overnight? I’m new enough that this is making me second guess my whole workflow, even though the print looked great right out of the wash and cure.

A specific moment was yesterday when I picked up the part and saw a crack line near a corner that used to look smooth. I’m hoping there’s a basic explanation I can test. Do you usually troubleshoot this by checking if it was hollowed with enough drain holes, making sure it was washed long enough, dialing back cure time, or switching to a less brittle resin for functional parts?

 

[Alan]

If it’s hollow, add bigger or more drain holes and orient so resin can actually leave during printing and washing. I see a lot of “one tiny hole” hollows that look great but keep a little pocket of resin. Also consider thicker walls or adding small fillets to sharp corners.

 

[Kirkis_Elf]

I’ve seen this when there’s still resin trapped inside a hollow part or pockets. First thing I’d check is hollowing plus at least two drain holes, then make sure it fully drains and dries before curing. How thick are the walls and is it hollow or solid?