I'm going to reface my blown bricks on the wall round my garden, should I pva the surface of the brick first?
Yes my advice would be to pva the wall first it gives a better bond for any rendering or refacing
You could do but the best way to rectify a spelched brick is to replace the whole brick as the brick as failed and any future water ingress will just force the face to spelch again with the frost also look at the pointing to spelched area
You can buy brick waterproof sealant from most builders merchants
Yes, also get as much sand and cement in all the blows as you can. blue grit is also better than PVA.
PVA (polyvinyl acetate.) is plastic based and only seals, grit-based primers do so much more plus hold the refacing in assuming a render much better.
I hope this helps
Samuel beechview carpentry