I am not sure what kind of horn you are using exactly, since I don't see that stated and it can make a difference. There is also a difference in what is commonly called
horn and antler.
This experience is based upon Deer antlers. Horn is different in some procedures.
Having said that here I go. If I am understanding by looking at your pictures what is going on they may not be as bad as you think.
They are warped still! Is that correct?
If that is what is happening try this! Reboil but his time, boil approx. 20 min, you can throw a litlle vegtable oil in the water a table spoon or so. Take the horn directly from boiling water and clamp between a couple of 2x4's or 2x6's, something substancial so as it can't warp while forcing the horn to a flat postion.
You will need gloves to handle while hot and don't be afraid to use the vice on the 2x's. Get them from hot pot to boards allready prepared, immediately! Clamp them between the boards as fast as possible and crank the pressure on the vice till you can't move any more. You want to postion so that vice is putting pressure directly and equally to each piece.
Usually depending on how bad they are warped they will embed slightly in the wood as the pressure is put to it and due to the temp they are at. Once clamped leave
at least 48hrs before unclamping.
Any warpage left and it usually is not much can be flattened on a belt sander with a large flat area to work on.
It has been my experience that boiling doesn't create cracks, it excentuates them. During shaping the sanding will help bring out the real colors in the horn again. Any cracks that remain after shaping can be sealed with Super Glue and a lite sanding will take off of the surface. Cracks in horn depending on the knife can add a lot of character to the piece.
Worst comes to worst send the slabs to me and I'll make a knife and give you credit for the handles!!!!!!!!
Hope this helps!
