spray the parts and glue or glue then spray

[Don Morris]

I put together a small bedside chest. I have it in three parts, a top panel, the bottom panel attached to the feet, and the case sides with drawers. I intend to spray the unit using a varnish. The separate parts would be easier to spray as individual pieces. So my question is, if I used Titebond's polyurethane multi surface glue...after spraying would that give me a bond comparable to using titebond III to glue bare wood to wood. It will be a lot more difficult to reach some parts easily, after gluing. What do you experienced finishers prefer to do? Any advice will be greatly appreciated.

V/r Don M

[Kevin Jenness]

I put together a small bedside chest. I have it in three parts, a top panel, the bottom panel attached to the feet, and the case sides with drawers. I intend to spray the unit using a varnish. The separate parts would be easier to spray as individual pieces. So my question is, if I used Titebond's polyurethane multi surface glue...after spraying would that give me a bond comparable to using titebond III to glue bare wood to wood. It will be a lot more difficult to reach some parts easily, after gluing. What do you experienced finishers prefer to do? Any advice will be greatly appreciated.

V/r Don M

Gluing to a finished surface is not generally a good idea. Assuming that you have some form of joinery to connect the parts and that they are designed in such a way as not to require sanding after assembly, mask off the surfaces to be glued, spray the parts and then assemble. It is possible to seal the interior only prior to assembly. Pictures would be helpful.

[John TenEyck]

I know of no glue that sticks to a finished surface as well as yellow glue sticks to raw wood. The only time I finish first is when there's no way to finish after glue up.

John

[Andrew Seemann]

The other thing to consider if finishing first is that the strength of the piece will now depend on:
1. The adhesion of the finish to the wood, and
2. The adhesion of the layers of finish to each other, and
3. The glue to the finish.

If using a polyurethane varnish, note that nothing sticks to poly well, including polyurethane. Layers of finish not adhering securely to each other could very well be the weak link.

Definitely something to test out first.

[Jim Becker]

I hate spraying into enclosed spaces. I don't mind masking to pre-finish to permit proper glue-up after finishing in some kinds of projects. So both pre- and post- finishing are valid processes if you handle them correctly.

[Don Morris]

I think I'm going to spend some time masking so I can spray the parts first.
will be more time consuming, but as Jim Becler said, spraying into enclosed spaces ia a PITA.
The masking will allow a wood to wood joint. Forgot to mention...there will be a couple pocket hole screws, mostly,
in some very out of sight spots. Covered by plugs of the same wood with the system Kreg has in a kit for that
purpose.We'll see....

[Curt Harms]

Gluing to a finished surface is not generally a good idea. Assuming that you have some form of joinery to connect the parts and that they are designed in such a way as not to require sanding after assembly, mask off the surfaces to be glued, spray the parts and then assemble. It is possible to seal the interior only prior to assembly. Pictures would be helpful.

That's what I've done, mask the surfaces to be glued then finish the insides or difficult to finish areas.

[Jim Becker]

Don, make yourself a few little custom sanding blocks using PSA abrasive with "stops" on them so you can, say, clean up an area that drops into a dado/groove/rebate even if it had been masked. The fence on the block insures you can't accidentally mark a show surface. I use 100 grit PSA abrasive rolls for this and scrap plywood and solid wood for these sanding blocks. A few swipes is all it takes.