Thanks for the answers!
@WillAdams, I put it on my shopping list.
@BrokenEndmill, do you have an estimate of how much faster boiled wood will dry? Does the wood become more flexible, so that it is less likely to crack?
And @gdon_2003, that’s a good suggestion. I think I will go for the risk of drying it faster (by putting it close to a radiator) and then repair the cracks. It should be sufficient for my project.
Btw., I put another slice into salt walter over night without boiling. The water is starting to get the same color, so the heat is probably not necessary.