Grapevine deadwood or live vein?

[Vali]

I have some decades old grapevines and I'm trying to find which parts of the trunk are dead and which are alive. Some parts look dead, but after scratching, I saw they were alive, other looked alive but were dead. Different parts have different colours, but I find it really confusing. Is there a better way to differentiate them except for scratching the entire tree? Thank you.

 

[Wires_Guy_wires]

The layer of live material in grapes is so thin that I found it the easiest to strip old bark when they're actively growing. At that time it gets a little thicker. But it's still difficult.
Good luck! I hope your grape isn't the same as the unrooted trunks they threw into buckets here, because those give up after a year.