Andy Dingley wrote:

Ammonia is highly water soluble, which is why you need the sealed
goggles or full face mask. Any mucous membrane, including eyes, is a
magnet for it.

Thanks. The plan was to stick some test blocks inside, so I'd simply be
reaching in to grab one and shutting the side door.

To vent the stuff afterwards you'll be wanting to open the main doors,
not just open a window. If the trailer has an aluminium frame, you may
also notice a little corrosion beginning.

It's a steel frame, but the ceiling has exposed aluminum skin. This is
something I hadn't thought of...

Personally I might use the trailer as the frame for a fuming tent, but
I'd make the tent itself smaller, just big enough to fit around the
table and allow air circulation space. The amount of ammonia you need to
use depends on this air volume, so you could easily be talking four or
five times as much ammonia for a tented vs. untented trailer. It's cheap
enough, but it is tiresome to handle.

Your point about the aluminum corrosion actually has me rethinking the
whole idea. The air volume is yet another excellent point. I might be
better off with a poly / 1x2 / duct tape containment underneath my deck.

I could tent the table, leaving an access door for the test blocks to be
removed.

Thanks Andy!
Barry