I think Redshirt's vote could use some refinement. Onmur's said some, but I think there's more to say on the science side of things.
[X] Try dispersing your Grief into particles smaller than the wavelength of visible light, and/or otherwise making it invisible.
I'd like to suggest other options as well. Namely Metamaterial cloaking and Matte color+ lever senors + light emission for active camouflage.
[X] Additional testing: Ribbons!
-[X] Channeling for Control Magic through Ribbon.
-[X] Channeling Grief Control through Ribbon. Attempt to use Ribbon to extend your range.
This should probably happen earlier, or even first. IIRC, unless Mami did something special we only have 30 minutes until the ribbon dissolves.
Vote modification:
[X] Choose your words carefully.
[X] Agree on the conditions that KB gives you detailed information on Kuroki Matsuko and any nearby meguca in need of Seeds; helps you with your SCIENCE session; and puts you in contact with stealthguca right now.
-[X] Be friendly with stealthguca: Explain what KB told you and try to schedule a meeting, but first and foremost explain and offer your cleansing powers.
[X] Once at Warehouse-kun, run tests:
-[X] Make liquid grief. Let it sit somewhere and check for corrosion and other effects later.
-[X] Channeling for Control Magic through Ribbon.
-[X] Channeling Grief Control through Ribbon. Attempt to use Ribbon to extend your range.
-[X] Whether your gem or body is the center of your range.
-[X] Try methods of non-witchy invisibility: nanoparticles, active camoflauge, light affecting metamaterials, and so on.
-[X] Grief nanoparticulate utility fog.
-[X] Whether you can use metamaterials for color.
Tests arranged in order from what I consider the most necessary and most trivial to least of both.
Fluid grief at the top since it isn't strictly
necessary, but it's really quite trivial, all we have to do is make it, and we know nothing about it yet. For instance, if it's transparent, like gaseous grief, but less witchy, that could come in handy in lenses and windscreens. That and just letting it sit in contact with other things for a while is a valid test that takes a little time, but no effort.
Plus, this way, if we run out of time mid test we've already gotten the important/fundamental stuff done.