SCP Foundation

subject(s) will strongly object if eye contact with SCP-2420 is broken in any way

Do you mean by the subject "object[ing]"? (Dictionary.com defines the verb "object" as "to offer a reason or argument in opposition") I guess you're trying to say that the subject is compelled to look at the SCP. But "object" is not the word you're looking for.

As a side-note (though more trivial), I feel you can just use the term "the subject" rather than "subject(s)". It's easier to type out anyway.

along with the words PROPERTY OF THE ARCANE INSTITUTE can be seen.

Uh, pardon me for saying this, but are you attempting to intro a new GoI? While I am no expert in the site's ways, I don't think this will do well for the article. Most GoI in the Foundationverse run on a unique gimmick to operate and exist (e.g. GOC with the "destroy anomalies" gig or MC&D's high-class auctions gig or the Fifthist's new age religion gimmick). What this article has shown thus far does not lend itself to unveil this GoI very well.

I am alright with putting the "Arcane Institute" there, but the way you're writing this gives the implication that you want them to be a standing GoI in the Foundationverse. If said GoI is interesting, it will stand.

The painting is somehow generating its own body temperature, which measures at 90ºCelcius.

Uh, won't "body temperature" imply that the subject in question has bodily processes? If the painting's identified as a living organism, I can work with that. However, 90 ºC is really hot. I never tried touching something that hot before, but I'm quite reasonably sure that being dehydrated is the least of problems (compared to being scalded or fried).

Things to address:

• The info from the very last addendum can be stated alongside the description.
• Beyond being a portrait with an anomalous effect that is apparently tied to an unknown group, there's very little to it. You may want to consider putting in a bit more context here, like why this SCP does what it does or the motivations of making such a thing etc.?

Object Class: Euclid

This is Safe. Class is based on the difficulty of containment, not danger. In this case, locking it up and not letting people see it is all that's required, and is generally considered the definition of "Safe".

SCP-2420 is to be kept in a room sealed by a Level Two security lock.

This ain't the game. A "level two security lock" isn't a thing on the site.

2420 must be concealed by a curtain which can be opened and closed automatically via remote control

What's wrong with putting it in a locked metal box of appropriate size?

No personnel should look at SCP-2420 for longer than six minutes.

I would think that it's best if Personnel weren't supposed to look at it in the first place.

At the twelve minute mark, the subject(s) will enter the severe stage of dehydration, in which case the test will be aborted without delay.

… Why are the tests being aborted? We have D-class personnel, whose job description is basically "human experimentation on SCPs, even if its lethal". There's a reason that they are death-row inmates and/or clones, you know.

Perhaps more interesting than the painting is the crate itself.

Tonal issue. Subjective statements like this have no place in SCP documentation outside of direct quotes of someone else.

and is considering adding them to the Groups of Interest list.

I see no reason that this needs to be mentioned.

Also found in the crate is an overview report of SCP-2420 from the Institute.

And why aren't the contents of this report included in the Article?

reveals a startling discovery

Again, subjective statements have no place in SCP articles.

The painting is somehow generating its own body temperature

Body temperature implies that it is a living thing: does a furnace get hot or does a furnace emit body heat? We have no evidence that the paunting is alive in any sense of the word.

but it might explain how it produces its anomalous power.

Unsubstantiated hypotheses do not have a place in SCP documentation. If you write something like this, you need an explanation for why it might explain the anomalous property of the SCP. And we never refer to anomalous properties as "powers".