How to Convert Between Clear, Connecting, and Scratched Glass
Pick the Right Input
The three families are separate blocks, not states you toggle in place. To change a build from Clear to Connecting, break the Clear blocks and re-craft them into Connecting Glass, then place the new blocks. The same applies going from Connecting to Scratched.
Conversion Path
Clear Glass is the common starting point. Craft Clear Glass into Connecting Glass for seamless walls. Craft Clear Glass into Scratched Glass for a worn surface. Stained versions follow the same path: Clear Red Stained Glass becomes Connecting Red Stained Glass or Scratched Red Stained Glass depending on the recipe used. Panes mirror their block counterparts, so Clear Glass Pane converts to Connecting Glass Pane or Scratched Glass Pane.
Practical Tips
Decide the final look before placing large areas, since converting means re-crafting every block. Keep a chest of Clear Glass as stock and craft variants on demand. If a wall mixes Connecting Glass with Connecting Glass Pane, the pane joints still hide, so you can combine both in one design without breaking the seamless effect.