How could we avoid bumping at the time of parting, especially at the time of second parting. We are keeping the parting time only 15 minutes for each section because of this we have to gently boil the 1.2 & 1.3 parting acid.
Thank you. I love to keep parting under boiling, but the manual that we are following never let us to do parting under boiling. They say "Place the cornets in the thimbles and immerse the basket into the nitric acid (33 %) at about 90 °C. Bring the acid to the boil and allow to boil gently for about 15 min or until the evolution of nitrous fumes has ceased. Remove the basket from the acid and wash with warm water. Repeat the treatment in a second bath of nitric acid (49 %). Allow to dry". If i only keep "15" Minutes at the time of parting, under boiling, definitely, i won't get a good result.