For guidance on the curing time of PU foam, the differences in cure time, and what these values depend on, see this post.
PU foam is completely tack-free after approx. 15 minutes. But that does not mean complete curing. For individual products, however, this value may differ, always observe the manufacturer's instructions.
It usually takes 4-5 hours for 1K products (one-component product) to fully cure PU foam. 2K products usually cure much faster.Tips & Tricks2K products also have a number of other advantages when it comes to building foam: they no longer need to pre-wet the foam to be foamed in a 2K product. Curing does not require ambient humidity for these products. The hardener contained in the product triggers the curing process. Also make sure that both products (1K products and 2K products) are handled differently. Always pay close attention to the manufacturer's instructions.