I personally think you could just stick it in any old box and call it a day, but it's not bad. It just highly passes a Locked Box Test.
The comma in the middle there is unnecessary.
Also, do these shadows exist solely in 2d space? As in, they only exist on walls, floors, etc? They need surfaces on which to exist, if I'm not mistaken?
Moving on…
Document 1553-C impresses me, good job staying in line with the tone of Wondertainment advertisements.
The concept is good, but your language and tone in describing it is…kind of hard to follow. The description tells us what it is, yes, but parts of it are kind of obfuscated such that its hard to be sure about the object itself.
Also, you mention Incident 1553-1 but have no Incident attached. Is this because it's coming later or was it an intentional decision to leave it out?
Also, your picture mentions White Lab-01, but the containment procedures mention White Lab-02.
All in all, it's pretty good, might need a midge of work, but manages to be highly clinical despite being a Wondertainment SCP. Upvoting for concept, clinical tone, and especially the Wondertainment advertisement.