Selected Answers

From Jon Cavallo of Jon R. Cavallo PE LLC on October 24, 2019:
Easy answer is "I have dry film thickness gauges t ...read more Easy answer is "I have dry film thickness gauges that read in mils or microns, but I haven't found one yet that reads in "nominals" or "typicals."" Seriously, this is currently an industry-wide problem which has resulted in a number of lawsuits, bonding claims, and just angry discussions. The simple answer is that applicators MUST be given a clear dry film thickness range (minimum and maximum DFT) by the coating manufacturers on their product/technical data sheets. If the range does not appear on the coating manufacturer's PDS and TDS, the affected document must be considered defective and resolution must be obtained from the coating manufacturer.

From Mike Beitzel of Modjeski and Masters on October 22, 2019:
They should respond the same, ask for clarificati ...read more They should respond the same, ask for clarification and be congratulated for reading the specification before bidding.

From Julian Hay of JhayCon Inspection and Consulting on October 21, 2019:
Ah yes…..”nominal”…..one of the most feared words ...read more Ah yes…..”nominal”…..one of the most feared words to be found on a set of specs! He or she contractor should be very......very…. nervous as it opens the door to misunderstandings, shame, blame and regret. (The contractor's.....not the specifier's eh…because they are “always right”, if only because they decide whether to pay the bill or not). Apologies if I sound a bit jaded, but I have been on both sides of the fence…as a contractor and as an inspector….and this word is a problem for all concerned. Never has a happy ending. According to the 3 well known mainstream dictionaries (which I looked up….again) “nominal" means: "in name or thought but not in fact or not as things really are;" "existing in name only;" "of, being, or relating to a designated or theoretical size that may vary from the actual.” To put it another way, in the coating industry where we measure our lives in thousands of an inch, it is a pretty worthless adjective when applied to a film thickness. In my experience, it is used in two situations, in no order of preference. When a specifier has no idea what he is talking about and wants to sound knowledgeable, competent and “in the know,”and because it sounds sort of engineer-ingy. (When questioned, the specifier, now being found out and likely embarrassed, will generally waffle and say things like “more or less” or “at least” or “exactly”…or “I meant,”none of which is terribly helpful.) When a contractor is trying to justify why he has less then the specified mil thickness on a substrate, most frequently used by epoxy flooring contractors when trying to justify that they have been found to have a measured 10 mils DFT on the floor and the specs call for 16 mils. “Oh, we put down a nominal 16 mils.” hoping that that explains it and he will get paid. Meanwhile, I digress…sorry about that….but this is a very nasty word, misunderstood by many, and all should be aware of it and tremble at its usage in the field of industrial coatings. Case in point: How about “ I will pay you a nominal $50,000.” Do you feel warm and fuzzy or do you have feelings of apprehension and confusion now? So, back to the original question: how should a contractor respond when he/she reads a specification requirement that "the nominal dry film thickness of the coating shall be 3 mils”? The wise contractor should immediately seek clarification in terms known and recognized by the industry as to what exactly is meant  by the use of the term “nominal.” Ideally, the clarification should be, well, clear and unambiguous, such as “a minimum DFT of 3.0 mils as measured by SSPC PA 2….or a minimum DFT of 3.0 mils….or 3 mils + or –20%, unless, of course, the specifier actually means “try and put on 3 mils, but if it's way less (or even way more), then never mind. We understand, at least you tried and we’ll accept whatever we end up with.” (Have never met that yet, still waiting for it though.) According to (all) the dictionaries, nominal means: "in name or thought but not in fact or not as things really are;" "existing in name only;" "of, being, or relating to a designated or theoretical size that may vary from the actual."