water etching troubles

i do so love to do water etching.
something about painting the wax on and then washing away the layers of clay.... i really enjoy the process... wax, wash; wax, wash...
i am currently having a problem with the process. because i do the waxing and washing steps over and over the water seems to be washing away some of the wax and then it also bites into the clay that i thought was covered. so the geometric forms end up a wee bit on the organic side! not really a problem with florals, but it makes the geometrics looks a bit....well, wambly. you can sort of see it here in the unfired picture and then the results...not to mention the gigantic crack!! it's funny, i had attributed that big crack to anxiously cooling the steel container too quickly at the end (i heard a funny pinging noise coming out of the container after i removed it from a 179 farenheit kiln). but i mentioned that i was having some technical problems to my wonderful spouse (who doesn't always listen exactly 100% when i start talking about jewelry) and he said "oh, is it too thick?" to which i said "OH!". stopped me right in my tracks! i have another similar one i'm going to run at the slower ramp for thicker pieces.
it's also kind of a mystery to me how to get realiable, smooth, unblemished surfaces in bronze. this is a tear-away circle pattern. it's VERY subtle, so if i went at it with sanders, i'd ruin my tear-away. so i burnished the circles before i fired. the next is deceptive because the circles are shiny, but i burnished them after they came out of the kiln and i couldn't see ANY evidence that i'd burnished those circles the first time.
more to come....