Palimpsest vs. Sandwich

I just wrote in a post that "to make a palimpsest isn't an exact science with norms. You can calculate many things ahead, but how the end product really will be, is often in the stars. It's really learning by doing and learning from errors." 
Often before I'll make a palimpsest, I scan the paper to look which picture will work with it. Therefore I create some sandwich montages with the paper and the pictures.
This example shows the difference between a clear sandwich montage and a weird palimpsest. 
I've used as paper a page from the German magazine "hobby - das Magazin der Technik" - No. 17/67 from 23.August 1967. The page shows the exploded view drawing from a submarine model:

First I made a sandwich montage in Photoshop, where I could adjust everything to have got in the end some different versions and hopefully one version which is "perfect":

Well, to think now that the palimpsest also will have the same appearance is unfortunately wrong. Of course, you can set everything perfectly in Photoshop and the printer as well, but if the paper is fed wrong from the printer, then it may already be problems. And many old papers aren't really suitable for printing. But often you just know this detail after printing, like here:

Therefore if you have got an unique paper, scan it before you print on it!