Quoted from DennisDodel:
There is a myth that old glass window panes are thicker at the bottom because of the glass "flowing" to the bottom over the decades. Not true but I wonder if this is a possibility with clear coated playfields. Will gravity cause the clear coat to slowly pool downward until it hardens?
It depends. I can see that happening but would need a combination of a couple of things.
With coatings, if you are dip coating and then hang drying then yeah, pooling is an issue. Can be mitigated (not eliminated) with proper masking.
Same thing can happen with spray or other coating techniques and laying flat to dry/cure, but in my experience the biggest potential for problems is with dip and hanging.
There are so many variables when coating an object that it can quickly become an art over a science. 6 sigma can’t save you here. Drives manufacturing engineers nuts.
Without knowing the process they are using exactly, (coating product, coating application type, age of mixed product before applying, cure cycle, application room temperature / humidity, etc...) all I can do is shrug and say maybe.
Another comment: no such thing as a “fully cured” coating. Only a “cured enough” coating. From what has been stated here some people are witnessing products that had an insufficient cure. To me, that suggests that the manufacturer applying the coating has been too aggressive in optimizing their cure cycles and haven’t adequately captured the tails of the distribution curve.
For example, I could give you a butter coating today and a diamond coating next century. The sweet spot is somewhere in between.
Old saying where I used to work: Cost, delivery, quality. Pick two.