difficult undercoat

Hello all

I'm using some Porter's limeproof undercoat sealer and having a devil of a time with very prominent brush marks in the undercoat.

Using all the manufacturer's recommendations, a reasonable amount of past experience with various paint applications and using all of the tricks of the trade I still can't get anywhere near a reasonable smooth top coat finish.

This undercoat is very puddeny, dries almost while you're applying it and goes on nowhere near as smooth as many other undercoat brands that I have used. It needs extensive rubbing back (almost to the bare timber again) and then a second coat, rubbed back again before moving on to the finishing coats. Never had this problem before.

I'll keep perservering with the application but I was wondering if anyone else on the forum has had past experience with this product?