Sorry to be clear as mud - thank you Richard.

Your fingers will get harder.

Now I don't recommend this to anyone...

I play bass in a rock band occasionally and play with my fingers rather than a pick usually. Probably because I don't play it that much in anger my right hand fingertips are not that hard as they are used to just fingerpicking a steel string. An evening of going for it on bass inevitably results in getting rid of most of the growth of nails of my index. middle and (slightly) ring fingers of right hand which I grow to fingerpick with (bummer!) and normally results in drawing blood on the middle finger tip (which I don't usually regret until the next day). But the resulting lump of scar tissue is still hard some weeks later.

As I said - NOT recommended.

And the urine thing is a myth apparently.

My son uses the excuse for not helping with the washing up as 'Joe Satriani and Steve Vai both say...' So we bought him a pair of Marigolds