How to figure out what resin has already been used?

[LakeFever]

Working away on this Hydrostream here and theres a few existing hull repairs and I started thinking I have no idea what resin these were laid up with? Thinking its wise to confirm this before I start laying new glass over top. Any idea how to test or check cured resin for what type it is? I wouldnt want to be laying vinylester over epoxy for instance

[XstreamVking]

Strange as it may seem, grind some of each area and smell it. You will def smell the difference.

[LakeFever]

Great tip! I rummaged through the email chain when i bought this hull last and he did say these patches were laid in with vinylester so that makes me feel better. They sure seem to be bonded in well.