melt in your mouth brisket?

Oh geez you have opened a can of worms.

There are numerous methods for brisket with everyone swearing they have the best one. Some people cook at 275 some at 225. Some wrap in foil, some wrap in butcher paper, some leave it alone. I can tell you that cooking to a specific temp on brisket doesn't work. Every piece is different so you have to cook until it is "done". You can test for doneness by probing it and seeing if the probe slides in as if it was a hot knife into butter.

Hopefully some of the members that have mastered brisket will chime in.

Andy 70 C is rather low for a brisket, most folks on here bring them up to 205* F that is around 90C 

http://calculator-converter.com/converter_c_to_f_celsius_to_fahrenheit_calculator.php

A rough rule of thumb on brisket is 190°F (87.8 °C) for sliced and 200+ °F (93.3 °C) for pulled..... BUT... each piece of meat is a bit different. So best thing to do is test it with a skewer/tooth pick at around 190°, if it slides in nice and easy your done, if not keep going and repeat the test an hour or so later until it's done.