Blotting Paper

[FredRydr]

...Is blotter paper really construction paper marked as something else?

No. Blotting paper is designed to draw a sufficient quantity of ink off the writing surface so as to prevent the blotted ink from returning to the writing surface, even with an immediate second application of the blotting paper.

My guess is you bought an old advertising blotting card. Those usually perform better than modern blotting paper bought from art supply stores. I never tried construction paper, but given it's thin weight compared to classic blotting paper, I cannot imagine it would have the capacity to draw heavy ink blobs without returning the blotted ink to the writing surface.