Do you only apply gutta using a dispenser bottle and nib?

You can experiment to get textured effects using spirit gutta and applying by dabbing with a sponge. You would need to be careful that the sponge was not too loaded with the gutta and that you did not overwork the area. It would be nearly impossible to completely remove the gutta from the sponge, though it could be soaked in white spirits and that would remove much of it.