Thread: pen finished in Lacquer cracking

Hi,
I have been experimenting with dipping lacquer as a pen finish, so far its been good. Recently however the finish is starting to crack.
It seems to crack mostly after I have applied a good few coats and left it to harden for a week and then sand and polish.
I have an old pen that I did in summer that has been living in the box in my workshop that has cracked and it is next to a pen with identical lacquer finish that is still fine.
I was thinking it might be related to the wet season here in Perth but then an old pen made in summer cracked. Could it be the thinners (too much / too little).
Not waiting enough time for it to harden (1 week). The other annoying thing is the opaque lacquer spots at the end of the blank that are not there before I sand and polish. I think this one might be water ingress on the side of the pen and swelling the wood just enough to lift the finish.
If anyone who uses lacquer as a finish could please give me some ideas on how to proceed.
I have attached some photos to show the finish cracking, the pen was made months ago and has only now cracked.
Thanks
Pete