I am often scratching my head with mugs. As an example some people have problems with Coralgraph. I have used Coralgroph mugs both by the pallet load and as individual box orders if I just want a quick top up, this has been over 5 years no problem. I had one delivery with a lot of broken mugs a few years ago. Emailed them and sorted in 24 hours, others have problems getting replies from them. I had a box of xpres mugs to see how good they were...yep they were mugs and they printed OK. Tried listawood AAA, not impressed with them as I had more with pin pricks in the glaze then I did with coralgraph. They weren't terrible but not fantastic.
What have I learned from all this? Only that I know nothing!
So there we are ..... no help what so ever.
Janners