What you are doing is accumulating brush marks. The 320 grit paper isn't coarse enough to remove one layer of brush marks before add another. Then after four coats is starting to really show up. Applying a finish on a top is just difficult with a brush. From where you are I would sand the finish with 220 grit paper using a hard rubber sanding block. This will tend to take off the ridges. Eventually when you get enough finish on you can start using finer and finer paper until eventually you wet sand the counter with 1500 grit paper and buff it with rubbing compound. It would just save you a lot of work if you would get an air compressor and a sprayer. With a sprayer eventually you could just spray the finish coat on and let it dry and you would be done without any further rubbing or polishing.

 

The brush strokes didn't show up on the other side and were almost immediate on the other side and i sanded them off between he 4th and 5th coat. Spraying is not an option for me.

I am guessing that 10% mineral spirits would help the product flow and lessen the brush strokes. The product didn't seem to move much after application so maybe the batch is bad.

 

If you are looking for a product to make it flow out better try Flood Penetrol. It will make the finish brush better however it will make it take longer to dry. You might also shop for a softer paint brush too.

 

If you are looking for a product to make it flow out better try Flood Penetrol. It will make the finish brush better however it will make it take longer to dry.

I'd definitely use the penetrol, but I'd probably use a sponge roller over a brush if you can't spray.

 

The finish you're using dissolves the previous finish below it. Your brush strokes seem to be pulling through two or more layers.
The slower you go and the more strokes you take, the worse it gets.
You will need to allow everything to completely dry. Use fans.
Re-sand with 320 to get flat and remove all brush strokes.
Buy the right brush. Brush wet from end to end. Avoid rebrushing.
Work fast. Allow to dry thoroughly. The end.

 

The Behlen rockhard finish is a urethane varnish. It goes on like an oil based polyurethane. It doesn't melt into the previous finish like lacquer or shellac.

 

Unless he sands through the finish, sanding aggressively should only knock down the ridges from the brush marks. The next coat should fill any scratches made by the sandpaper.

 

applying varnish

4 coats?? looking at the top I'm sure you didn't THIN the varnish with mineral spirits. Thinning is the only way I can make it look like I sprayed it. Thin varnish with 40% or more with spirits will allow the varnish to flow out before it dries. An old salt about 80 in the boat repair yard 50 years ago taught me that. He was slapping on a coat of varnish with a old crusty brush that looked like you sprayed it.