The seam sealer was this: PRO FORM - Products
I had the tube open from another project a few weeks ago. Laid it in from the tube and with a nitrile glove on, smoothed it with my finger. The masking tape (and pulling it off as soon as you’ve run your finger through) is key to keeping it crisp looking.
Good advice here! This is on my "to-do" list. Is one tube enough for this job?