how to finish inside of finger jointed box

[tom coleman]

should I pre-finish before gluing
should I use a minwax product that combines stain w a finish coat
or
should I use masking tape on all inside corners and finish after gluing

[Phil Mueller]

Probably a little late for this, but I completely finish the inside side of the board prior to cutting the joinery. Just a whole lot easier than getting a nice finish on assembled inside corners. You could also spray rather than brush or wipe, if it’s already assembled or cut.

[glenn bradley]

I would pre-finish. I pre-finish any hard to reach or troublesome areas before assembly on projects large or small.

[Lee Schierer]

You would want to protect any gluing surfaces from the finish. Painters tape can do a pretty good job of this. I apply the tape so that the "finished area" is slightly inside the joint. I usually only protect the face grain areas on box joints as it is pretty easy not to get finish on the end grains and inside areas of the fingers.

[Bill Adamsen]

For boxes ... spray (or brush/roll/wipe) insides at least before milling. Outsides typically require sanding afterwards (the tails at least) and are easy to spray afterwards, and would require "touch up" anyway. I try to "underglue" boxes because cleanup is so difficult, and with box joints there is a ridiculous amount of surface area.

[Charlie Hinton]

I have been finishing the inside of my boxes and both sides of inset lids/bottoms before assembly too.
I do this regardless of the style of the corner joints.
Most of the time I will also rub a little paste wax (no buffing) right where the glue line will be and it makes removing any squeeze out very easy.

[Jon Nuckles]

Probably a little late for this, but I completely finish the inside side of the board prior to cutting the joinery. Just a whole lot easier than getting a nice finish on assembled inside corners. You could also spray rather than brush or wipe, if it’s already assembled or cut.

This ^^^^^^^

[Todd Mason-Darnell]

I am very early in my woodworking journey, but I have already found that pre-finishing the inside of the box before glue up makes life so much easier.

[Jim Becker]

I am very early in my woodworking journey, but I have already found that pre-finishing the inside of the box before glue up makes life so much easier.

I actually do that with cabinets and my tack trunk commissions, too...the added time is balanced really well by the lack of shooting finish into a box, which is a nasty task and hard to get good results with, too.

With this application (finger jointed box), pre-finishing what will be the "inside" surfaces of the material does get finish on a small amount of material that goes into the finger joint, but that's easily remedied with a little sanding block that has a "fence" so you can scuff what will be the hidden surface without overshooting and damaging what will be the show surface on the inside of the box. I use this technique when using pre-finished material for cabinets to remove/scuff the finish where there will be butt joints or other joinery without damaging places that will be visible.

[Jon Nuckles]

For finger jointed or dovetailed boxes and drawers, I recommend applying finish to the inside faces of the pieces before cutting the joints. No need to do any clean up before assembly that way because the surfaces that give the joints strength will be freshly cut. The interior face of each board only contacts end grain of the other board in the joint and plays almost no part in holding the joint together anyway.