Hey Craftgirl I think the most importnat part of getting your top textured is doing it at the right consistancy.............I would describe the consistancy as thick instant pudding, then don't cover cause your will flatten the tops off............Ash is possibly an issue and I am not 100% sure how to combat that one. I spray all my soaps with Isopropryl Alcohol before putting in the fridge as I don't like to gel.
To texture the tops you really can use anything..........I use iceblock sticks, just easier I think in log molds but some use teaspoons and whisks.
I use folding type motion like as when you are folding flour into a sponge recipe LOL. Practice and suddenly it will just fall into place, I think that is the secret. HTH.....................Lyn