Dw tried to teach igents about gemming failure, but it was wasted info on many igents. Instead of using DW's knowledge as a starting point, many igents simply decided he was wrong and that they knew better.
Why not go to the factories and major quality workshops and find out if gemming failure is true. I did. Actually, l didn't even have to ask them in some cases, they simply volunteered the info and said it was "common" or "happens all the time".
BUT some igents actually did ask cobblers about gemming failure and many cobblers wrongly stated it was a myth. See...the igents were asking the wrong questions, so they got the misleading answers.
When cobblers say gemming failure doesn't exist, you ask them the following question.
1). Did you strip back the cork to check? This tests whether they really know that gemming failure exists and it tests whether they are cutting corners when they do refurbishments. See, some cobblers don't want to do rebuilds and recorkings Too costly in terms of time lost and they lack the equipment for proper rebuilds)...all they do is a resole without checking for commonly occuring gemming failure, THEREFORE igents report cobblers say gemming failure doesn't exist, but what it most likely means is that the cobblers are not taking the time to be thorough to check for failure. Lots of cobblers are like that.
In the old days when goodyear welted shoes were common the factories used to sell gemming tape because gemming failure is so common. But igents don't ask the right questions and do proper research so they don't know the real situation. Manufacturers of highend goodyear welted footwear will initially play dumb about gemming failure, but when you let them know that you know they do come clean.