For the first simple tests we filled the tube with NaOH water solution – The NaOH does react with Aluminium and then will form hydrogen bubbles, however it will not react with Nickel metal. The coating is nicely closed for the inner surface – except for where the G1/8 plug is screwed in. I think we should modify the plug design a little bit or grind the sharp edges down before applying the Nickel coating. Nevertheless we think the overall quality is pretty good and we will continue our testing procedures.