What if boiling and compressing the horn doesn't straighten it?

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?

try using a small bench vice with them pinned between the wood spacers after boiling once more, then putting them in the oven at 150 degrees for 3 hours, vice and all. that outta do ya. sand all that CA off first, though.

There's no way of getting all the CA off. The scales were badly cracked and a lot of the glue wicked down in. Do you think that'll get in the way?

I don't remember where, but I posted a long answer to working with horn somewhere.

In short, boiling will not make horn plastic enough to do very much with it. As hard as you can try to boil it, you will never get it hotter then 212F. Dry heat somewhere between 300 and 350F will make the horn soft enough to change it's shape and make it stay that way. Over 350 and you will burn it. Hear a "crack" and it is gone. You will need to clamp it as mentioned above, but be careful because when you get it solf it will imprint with the grain of the wood or whatever you clamp it in.

I hope this helps.

Will N.

WillN makes a good point. I always boil and use the oven at a low temp because I don't want to risk ruining the scales. Mine have always eventually turned out fine, but sometimes I need to repeat the process a couple times. I don't know that the CA will get in the way or expand/shrink, but I wouldn't worry about it. Just try straightening them again. You can sand and buff afterward.