Anonymous ID: 635f02 Nov. 5, 2020, 6:47 a.m. No.11476863   🗄️.is 🔗kun

>>11476840

Yes.

 

Top 20 Security Printing Methods Explored

www.belwo.com/top-20-security-printing-methods-explored/

Method for applying chemical watermarks on substrate

https://patents.google.com/patent/US6334678B1/en