Thanks guys for your sympathy.
It is not the first of my bows that is broken and I am afraid it won't be the last …
… I am shocked hickory broke. Wonder if the break was from a board bow design?
Yes, it was from a board.
But I think the main problem was, that I heated the limbs too much. They are so thin, that the heat went right through the whole limb and they went to brittle.
The silk-backing, only one layer, was not strong enough to save that.