So I've got this set of very old black horn scales. They were in real bad shape. I soaked them in neatsfoot oil for 2 days, sanded, glued the cracks, boiled for 20 minutes, put in a vice (with spacers, between planks of wood) for 2 days, sanded, soaked in neatsfoot oil for 2 days, glued some more, gave them a CA varnish and serious polishing and...

They're back to exactly as warped as when I started. (They look a lot better though!)

After coming out of the vice they were nice and straight, but as I polished them they slowly warped right back.

Is this something I should just live with (it isn't the end of the world if I have to guide the razor into the scales), or do I need to apply more boiling and compression than I did?