Moisture risk changes across a part's life, not just at print time
Most moisture advice for FDM focuses on the filament spool before printing, but a finished part faces its own separate moisture question once it is in use: a planter, a bathroom fixture, or an outdoor bracket faces ongoing exposure the original filament-drying advice never addresses. This tool separates that service-life question from the spool-drying question already covered elsewhere on this site, and checks your material choice against the exposure stage and level you actually care about.
How the comparison works
Each material family carries a general moisture-tolerance rating, low for Nylon, medium for PLA/PETG/ABS-ASA, high for TPU, which is compared against your stated exposure level. A meaningful gap between tolerance and exposure is flagged, with a protective finish offered as a way to partially close that gap for occasional exposure, and a material swap recommended for anything more sustained.
Worked example
PETG (medium tolerance) facing high, sustained moisture in its post-print service life with no coating planned: the tool flags a real gap and recommends either adding a genuine protective finish or reconsidering material, rather than assuming PETG's general "all-around" reputation covers this specific case.
A common mistake
A frequent error is confusing this service-life moisture question with the separate question of whether the filament spool itself needs drying before printing. A part can be printed from perfectly dry filament and still face real moisture risk in its finished use, and a spool that needed drying does not automatically mean the finished part will struggle with moisture later. Keep the two questions separate.
Limitations
This is a qualitative planning comparison based on general family tolerance, not a waterproofing certification. It cannot account for your specific coating product's real performance or a part's exact geometry (thin walls let more moisture through than thick ones); test under conditions that resemble real exposure before committing a part where moisture failure would be costly.