Originally Posted by barrelntrigger Uhhhh, what...
A half-canvased suit has fusing down the front just like a fully fused, though the lapels will get canvas instead of fusing. If they fused only half the front, there would be a line across the fabric where it would suddenly hang differently. You can stop the canvas halfway down since it isn't bound to the fabric. That's why it's called half-canvas and not half-fused.
I looked for one of each type, generally getting them as orphans and cheap, and took them apart. Pictures and diagrams are nice, but it's not the same as taking them apart to see and feel for yourself. I find it easy to identify the multiple types now. I've learned that there are more than just three types, as some "fused" jackets have no canvas at all, and others have a small piece just in the chest.
This is my observation.
Full canvas: Canvas down the entire front; no fusing (except collar & cuffs).
Half canvas: Fusing down entire front except lapels. Canvas in upper half and lapels.
Fully fused: Fusing down entire front, including lapels. No canvas.
And then there are a hodgepodge of items between "fully fused" and "half canvas". The half and full canvas ones I've seen have a second smaller layer in the chest. Some fused jackets have just this layer. That threw me at first, making me think that it was a half-canvas that just ended higher, like in the first photo here: http://www.styleforum.net/t/309175/a-sacrifice-to-the-sartorial-gods
Some "fused" jackets will have just that and canvas in the lapels. They don't have canvas that comes halfway down the front, though. But if there's fusing in the front, it's the entire length of the front.