Seed paper

I run into this a lot with recycled stock, or “Kraft” type paper. I consider this stuff a contaminated stock. The “seeds” such as you describe,would prob fall into this domain. i would run a soft, recovering, makeready sheet. i use either black urethene, or thick latex, depending on what is in the stock. Not just soft layers of other stock. You want a “rebound” material to come back as the impurities are in different positions each sheet. Maybe consider having you image made from Copper or Brass plate.
Unless there are rocks in the stock, a die cutting die should survive okay. The rule is very hard and very sharp.

I have no experience with due cutting seeded paper, but I have successfully and beautifully letterpressed on Porridge Papers’ wildflower seeded paper. The wildflower seeds are rather small and soft and did just fine with my photopolymer plate and 8x12 C&P platen press. No damage was done to my plate, but I was mentally prepared to order another one in case it did. I know larger and harder seeds could definitely be an issue, but the soft and small seeds of the wildflower mix did great!

Thanks for the feedback. We are looking at all the possible issue and you helped to answer a few.

Use rubber sheet under the top sheet of the packing and have a metal plate made, not type, Also avoid small type sizes. I cut small heart shapes on paper with a small seed inclusion such as forget-me-not.

I have worked with Porridge Papers’ seeded paper to extent and haven’t really had any issue. If you’re printing with polymer, I’d order an extra plate to be sure, likewise avoid some large solids to avoid damaging any part of that art.
Metal plates are ideal to be sure here, especially with larger seeds.

Die cut some coasters for a wedding too and saw no issue after 3500 of them. As mentioned above, get softer makeready.