What to do with Spline?

I remember years ago when putting in spline, I used to say to myself as I inserted it around the corners "please don't snap, please don't snap" but I still had many pieces snap on me.  That was very frustrating!  That's when I decided to soak EVERY piece of spline before I use it.  In the years since, I have not had one piece of spline snap.  Even a very brittle piece becomes so pliable after a half hour soaking that I can wrap it around any corner easily.  Some may say it will expand...maybe a little...but not to the extent that it should not go into the groove.  Soaking also makes it easy to miter the edges without any breakage. This material is the same material that flat reed/splint comes from...and of course you wouldn't think to use this material without soaking it.  It just makes sense. 

Below is a chart to help you select the size of spline you will need.  Measure the actual groove width and then it will correlate with the size in the left column.