Any thing that paint will not reach will benifit from filling. Where I have alot of gaps and painting white I sometimes spray small gaps with spray can of white shellac or kilz.

Painting of wood paneling tends to emphasize variability in uncaulked seams. Careful caulking is an easy way to avoid this appearance problem and make everything look uniform.

Asking wood that runs at right angles to look like it was formed from one seamless block of plastic is asking too much. The wood will move, the caulk will tear free, and it will look worse than the natural seam.

The "caulk it all" look is very seductive, but illusory.

Casey

If you want a wall that looks flat, replace the paneling with drywall.

Or is it just the dark colouring that your wife doesn't like?

It's the coloring she objects to. We don't care about the vertical lines in the paneling. I'm referring to the corner seams and seams along the baseboard and ceiling.

Test paint a small out of the way spot. Wait 24 hours and make sure you can't scratch it off.

I've done this several times. just use a good caulk with a long life.

caulk moldings to ceiling & walls, caulk joints of paneling.

I like clear caulk, even if painting over it. just seems to

flow better. it goes on white, so you can see where you

stopped, then when dry is clear.

I use Dap's brand Alex 35 year caulk

best of luck

Our 10' high family room was oak picture frame paneling, dark and ambered. About 10 years ago we painted the entire room plus the beamed ceiling a rich cream color. The painter's nephew was a body shop guy, and he caulded every seam in the room. It took a few hours but well-worth the effort. The only gaps in the paint are from seasonal shifting in the foundation, a problem we had anyway.

Here is what happens when you paint over caulked wood. This is outside, so not a concern for me.

The paint will crack whatever you do.

Paint it.

Put tape as a mask.

Caulk it.

Then remove the tape.

now you won't see the paint cracking.