Some early decals were not a waterslide nor an adhesive backed type, nor were they clear coated, but they tended to survive very well. They were a varnish-set type (placed onto a wet clear varnish which had been applied on top of the enamel). These had a strong varnish coating on the actual transfer itself which gave the effect of being painted onto the bike once the paper backing was later soaked and removed. I think the only way those can be removed would be to chip and scrape them off as you would to remove spots of dried on enamel. I believe the head tube and seat tube transfers on my old Frejus is a good example of this type. They have chipped in spots over 35+ years, but still have the textured feel of hand painting over the beige enamel, and there is no question that they will not peel off - like the ol' 531 decals did, almost instantly.
