I've done breaking with and without spacers....the most important thing is that you understand the physics going on and understand the differences in the types of strikes required with each break....wood, definately pine...12" square for adults, 6" or 8" boards for kids depending upon size.
Now cement is actually very easy to break, as it is simply a fine powder....it gets harder when you add some water and rock and turn it into "concrete" (lol...sorry, couldn't resist). I like the 8" x 8" x 16" patio block, although I can't seem to find them anymore. Also the scalloped edger stones can be used, although they are much much easier, simply due to their dimensions.
I have broken ice before....it was pretty easy...couldn't really find a good way to freeze a large enough slab to make it challenging.
A buddy of mine used to break bats over his shins...I was reminded of this tonight when one of the kids on the t-ball team I'm coaching missed the ball and whacked me in the shin....unfortunately, it was with an aluminum bat, and it did not break!! LOL!
I really would be interested to try breaking roofing tiles like I always see them breaking in Korea, but I don't know where to find them.
I would like to try ice, does anyone know the size of block ice off hand?, I have a commercial freezer in the basement, maybe I could make a form for it, what size/thickness would you think?
Also is the world record for most boards in one minute still around 412 or so? I'd like a crack at that record,hehe
We are always hearing about all these world records in breaking who is the governing body and who is inspecting these boards before and after.
I attended a tournament in Harrisburg, Pa 2 years and a broken board landed near me and when I picked it up it had been scored with a razor. The artist ran over to me to get the board and ripped it out of my hands.
Without weight standards, quality standards and inspection... all claims in breaking are worthless.
However, I was impressed that Master Whiley in Southern Florida broke 453 boards in 60 seconds as a charity fundraiser on TV. I am not sure I could break 453 taco shells in 60 seconds.