@OldBoot,

  • You are correct: seam seal first, then spray the tent floor.
  • There are three products at work here: 1) A seam sealant for the seams on the tent, 2) a tent fabric sealant for the inside of the tent or fly (this is the part that typically flakes off), and a DWR Treatment for the outside of the tent. 
  • You want to use the Polyurethane treatment on the inside of the tent floor and the DWR treatment on the outside.

Hope this helps!

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