I have used your Extra Strong Matt Varnish and I have applied it with a brush but it has left visible brush strokes. Can I water down the varnish and apply with a small foam roller?
Yes the varnish can be applied with a small foam roller or a good quality brush. You could dilute the varnish etc. I often dilute the first brush coat to create a thinner base coat (by watering down by 20%). Then when applying the first full coat it’s easier to spread, dries a little slower and goes further.