I put a hose clamp on the neck and tenon of my hollow forms to reduce the potential for cracking and to help keep the opening round while drying. I turn a 1/2" collar on the top opening for my steady rest to ride on while hollowing. I put the hose clamp around the collar and bottom tenon then check them once a day for the first week or so while it's in the drying box. It's amazing how loose the collar will get day by day. It can be very tight and then 24 hours later very loose. After about a week or so (it varies) the shrinkage stops and collar will stay tight from day to day. It's usually a week or two later that the piece is dry enough to move on to the second turning. The collar gets turned off during the second turning. I've not done any true scientific comparisons but experience is that the pieces with hose clamps do much better than my experience prior to using them.