hi..
does primer and surfacer gives the rough effect that can be used on tanks etc.?

It depends on what no. they are. #1000 gives a smooth surface. #500 will leave some texture, but in an even distribution if you use the spray type. If you use the brush type, you can make rough texture using a hard brush, but it need some experiment and practising.

For a textured effect, use your regular brush cement. Brush the whole area and stipple it with a hard bristle brush. Adds great texture. Sand it down if it gets too rough for your liking. Very simple and you have good control of the method.

plasticbattle is correct. You can 'control' the amount of 'texture' by rewetting the surface with your liquid glue (which will keep it soft) until you have the softness you need, and then either use a regular brush, toothbrush,etc to 'draw' your texture onto the surface.
Also.....if you require a 'hard' demarcation line, just use masking tape (not the blue tape), and lay it down where you want the seperation to be, and lightly run a rounded embossing tool along the tape edge. Apply liquid glue as before (might not want to be sooo sloopy with the glue) and stipple as you would, then let dry for approx. an hour or so, lift tape, careful to pull tape back at an angle against itself fairly slowly, and...voila!
hth.

Tread.