The best way to apply clear coats is a good spray gun, But if you have time there is no reason it can't be done with the right brush because all coats will be rubbed back and polished no matter what tool you used to put the clear on with, The key is light coats . As a general rule it will take 8 to 10 coats to achieve a flat plane that is full ,,Being full and flat so that you can polished down on it. it's the same in either of the traditional finishes of shellac ,varnish , nitro.
So if your using a brush , buy a paddle brush made by Holcraft and it can be bought from Art stores.
The reason it's so good is , its wide, it puts light coats on , it leaves minimal lines to be polished out.... You don't use it like a brush , you put it on in one long swoop and then do another long swoop so you only get one line .
If your trying to fill the grain and achieve a flat plane then paint the clear coats on across the grain not with the grain.

I highly recommend this paddle for anyone who is doing the brush method.

http://riotstores.com.au/item/174801-holcroft-paddle.html


All the best Pete

Thanks for that tip, Pete. I intend to do some shellacking between now and September.