this type of hash as well as bubble hash are all about what is on the surface of the material... this isn't an extraction from inside the plant. So, without turningn it into dust, you do want to break it down to individual buds as best you can... for bubble hash (using icewater) you don't want to damage the plant material or you'll get green hash (chlorophyl contamination) . This is inevitable with dry ice hash method, so just don't break it down "too much", but increased surface area will help knowck off more trichomes.
ice-cold water is what knocks the trichomes off in bubble hash (not the ice!! if ice is jagged it will cause contamination). with dry ice it's so cold just a little jiggle of agitation will make plenty of stuff fall off easily. so expect it to have a green shade to it. It's still great stuff and a hell of a lot less time invovled to make it (dry ice method). It won't be as clean as ice-water bubble hash, though. You should try that in future sometime.. buy a little portablel washing machine -- doesn't have to be the over-priced bubble bag dude washer. Just find with wiht a smooth tub. nooks and crannies are no good.