Small argon cluster GCIB sources are increasingly used for analytical depth-profiling by secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). Argon clusters greatly reduce the damage introduced to the specimen during depth-profiling, making it practical to do so for many organic and polymeric materials for the first time. This has greatly extended the range of materials to which XPS (for example) can be applied. Gas cluster sputter rates of different polymers differ a great deal, and X-ray damage (of the type that accumulates during XPS analysis) can change these sputter rates markedly. While generally less damaging than monotomic sputtering, gas cluster ion sputtering can nevertheless introduce damage that is very noticeable in some materials.