Assemble-Finish or Finish-Assemble?

I assembled the bathroom vanity before I finished it (stain, polyurethane, sanding). That went fine for most of it, but it was difficult to sand coats of finish next to interior edges. And it meant locking cabinet door panels in place with polyurethane rather than letting them ‘float’.

So for the salon table I opted to finish everything first. Sand, whitewash, polyurethane, then sand. I taped the joints ahead of time to keep the to-be-glued surfaces clean.

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My verdict? Neither approach is optimal. Pre-finishing down sides:

• Pre-finishing added time to apply and remove the tape. That wasn’t terrible, but tape was difficult to peel off so it took a while.
• The taped portions weren’t level with adjacent finished portions. Light sanding was required to ensure tight assembly.
• Sanded edges resulted in slightly rounded edges, so butt joints weren’t as tight as they should have been.
• Miter joints may require sanding at the top / bottom edges for a clean finish. Pre-finishing means re-finishing after this sanding.

On the up-side: Full coverage. There won’t be exposed unfinished edges when the table expands or contracts with time.

The Conclusion (Lessons Learned)

So what will I do next time? A hybrid:

• I’ll refrain from sanding butt-joint edges since they won’t be seen anyhow and I’ll get a tighter fit.
  • Everything else will be pre-sanded
• I’ll pre-stain but NOT pre-polyurethane before assembly.
  • Any needed post-assembly sanding will be easy to re-stain. Things get messier if polyurethane is already in place, however. It’d block the stain and require sanding. Thus I’ll just wait on that step until the very end.
  • Staining may not require pre-taping (at least not water-based). I’ll have to experiment.
  • Exception: Floating door panels: I’ll fully finish pieces that are intended to float with expansion and contraction. I’d rather not see unfinished edges over time.
• I’ll continue to use an Aerosol polyurethane rather than a brush-on. It may cost more, but NO brush hairs to pick out. The finish is also more consistent and less heavy.