Hi, I am having a sheetmetal worker build a stainless steel sink for me and was wondering what type of material is used for the undercoating to help prevent condensation. Is it some type of resin? The individual building the sink does not know as this will be his first sink. Any information will be appreciated.

Hi !
As the bottom of the sink will be a metal sheet, when water will drop on it, it will sound like a bell.
Try to coat the underskin of the sink with sheet tar used to waterproof roof tiles. it is sold by the sheet or roll and stick when heated with a blow torch. It will damper the sheet of stainless steel and, adding mass to it will also help for condensation. (because it convey heat far less than the stainless steel)
Hope this helps.

You might try a spray can of truck bed liner or automobile body undercoater, (made to provide insulation and sound dampening on the underside of car bodies), builds thick, easier than tar based materials. I have a stainless steel sink but never have coated it, but I last had it set up in the dry SW desert

Thank you. Yes I am hoping it will help with noise reduction as well because I live in a third floor apt w/wood floors.