Chuck Clark wrote:
When moving any tatami or modern sport tatami substitute you have to be very careful about the way you carry it, etc. It should always be moved perpindicular to the floor instead of flat. Zebra mats are constructed with the covering glued to the foam. If carried or stacked wrong the covering can be broken away from the foam which causes the bubbles. They should be flat and not bent. Traditional tatami should be handled in the same way.
I can't imagine how much I would dislike working on sport tatami on top of jigsaw foam mats... Ughh! (as I saw described on another site) Excessively soft mats create many problems for budo practice. I was on a very soft foam mat with a canvas cover for a weekend in Houston recently and my knees and lower back are still talking back to me. My advice is the firmer the better as long as it absorbs shock appropriately.
Just so you will know, the jigsaw mats underneath aren't my idea but the karate guys we train with just couldn't part with them being there. It does make things softer but I personally don't need them. As for Jim Baker, his bad back is legendary so I suspect he would like the feeling of our current mat. I train on the zebras on a gym floor and the Zebras on the jigsaws and the latter does feel better. Too soft is no good and can be dangerous. I have trained on that as well. We used to have a thick foam mat on concrete and that was dangerous. It was unstable and if you hit wrong, you went all the way to the floor through the foam. Our guys though have learned to take ukemi on everything including the gym floor (not too much though!)
We were recently in a seminar in Mexico where they had what appeared to be some carpet padding with a vinyl mat over it and it was paper thin. We did our regular break falls and everyone came out OK but very bruised when it was over.