My vz70 doesn't seem to have the gray phosphate coating you describe on the 75. After I finished sanding, I soaked in vinegar to remove the remaining blue, inside and out. For the first carding I used steel wool outside and a copper brush inside. I applied the second coat of acid at lunch today and just finished boiling. The black "fuzz" is much softer than I expected it to be. I'm working a long day tomorrow, is it ok to wait a day before carding? I'm afraid to let it rust all day while I'm gone. Sorry for the thread hijack, I should probably start a new one or pm you.