Assuming you mean, are the words "clean those brass" adjectives, the answer is no, maybe, and yes Clean is a verb. Those is a demonstrative pronoun. (Some people might call this a form of adjective, as it is a modifier.) Brass is an adjective: a brass trumpet, a brass bookend. Note that brass is also a noun in some uses: the brass on that uniform is shiny, the brass in this orchestra is very good
You can clean a brass telescope. Over a duration of time, brass starts to oxidize. To remove this, can use vinegar and salt. You can also use a concoction of chemicals that is premade, usually by a company that specializes in brass.
http://home.howstuffworks.com/how-to-clean-furnishings3.htm
There is an effective way to clean brass door knobs. The first thing they need is to determine if the knob is brass plated or solid. If it is plated, use caution in the cleaner that they use.
Brass will oxidize and turn greenish. Moen and Delta have PVD brass finishes which are more resistant to corrosion.
To clean brass, mix equal parts vinegar and water or use a commercial brass cleaner. Apply the solution to the brass using a soft cloth, rubbing in circular motions. Rinse with water and dry thoroughly. Avoid using abrasive materials that can scratch the brass.
Try a little WD40.
Brasso and elbow grease.
The workmen are brassing the elevator doors to make the metal look shiny and clean .
Lyman turbo Brite Brass Case Polish receives high marks for it's outstanding ability to clean brass. Brass can also be cleaned naturally with lemon juice or vinegar.
To clean a brass plate, first mix a paste using equal parts of lemon juice and baking soda. Apply the paste to the brass plate, scrub gently with a soft-bristled brush, then rinse with warm water and dry with a soft cloth. Alternatively, you can use a commercial brass cleaner following the product instructions.
Ammonia can cause brass to tarnish and corrode due to its high alkalinity. It can also remove the protective layer of lacquer or varnish on brass surfaces, leading to discoloration and pitting over time. It is not recommended to use ammonia to clean brass.