Can't seem to hide the seam. Any suggestions?

[Soundwave]

I have 2 pieces of wood butted tightly together and I can't seem to remove the visibility of that line. I used bondo and primer but after I sand it down so that both pieces are flat and smooth, that line shows it's ugly head. I'm more worried that it will come through after I paint it. Not really sure what to do about it. If I rub my finger over it, I can still kinda feel it so not sure if this will be a problem when I go to paint or not? It's like I need something that's thinner that could penetrate into the seam better but Primer doesn't seem to be doing it.
The paint won't be anything fancy, I just plan to spray on some premium exterior water based paint but since my arcade cab will be white, I suspect it'll show.

[dezmond]

Cut a small vgroove in the seem and use bondo.  Make sure you don't just use your hand or fingers on the sandpaper.  Take a good flat block and sand smooth.  After that I would spray some primer on it and see how it looks. 

Worth a shot 

[Slippyblade]

Make sure you don't just use your hand or fingers on the sandpaper. 

This is so true.  Your hand will press into the paper causing it to sand a divot into filler material.

[Soundwave]

Cut a small vgroove in the seem and use bondo.  Make sure you don't just use your hand or fingers on the sandpaper.  Take a good flat block and sand smooth.  After that I would spray some primer on it and see how it looks. 

Worth a shot

Thanks, that's a really good idea. I use a belt sander, orbital sander and a manual block sander depending on what I'm doing. Maybe next time I should just leave a slight gap in between them and fill it.

[dezmond]

If you are using some sort of manual block sander, when you put some bondo on and sand it, you may see the seam but if you use s good primer/sealer and a couple good coats sprayed on you shouldn't see it anymore. When I laminate wood together and then sand it I always see a seam but after the primer is on and blocked its all good. 

[Kier]

Cut a small vgroove in the seem and use bondo.  Make sure you don't just use your hand or fingers on the sandpaper.  Take a good flat block and sand smooth.  After that I would spray some primer on it and see how it looks. 

Worth a shot

The same here. I always cut a small groove, allows for a little error and takes the jarring line out.

[kahlid74]

It's already been mentioned here, but use a block sander to prevent divot creation and then a good primer, two passes and it won't be seen anymore.

[n3wt0n]

If you can see it in the primer you can bet real money you will see it in the final paint coats. Remember to use a sanding block and you may need high build primer or even some more bondo/filler depending on the depth of the line.