You can still ask me questions.

If necessary, click "ask TA for help".

My team "Architectural Architect" and I will try our best to help you.

Answer: According to the regulations, the blueprint should be stamped directly. If the seal is blue, the design unit may save trouble and stamp it before printing. There are also architects and architects' seals, which are originally blue. Check it yourself.

Supplementary answer: I haven't stamped the sulfuric acid diagram yet. We all stamped the blueprint directly. So it should be a blue stamp, stamped or dry. Look at that. Feel it. Just smell it.