Cleaning the saw should be done with just a cloth. If it is important to you to remove rosin buildup (this is just cosmetic – it wont impact the musicality of your saw) – use either soap and hot water or possibly alcohol.
If you need to scrub, do NOT use anything metalic (ie. wire brush, SOS, etc.). If you do, then mcroscopic particles of your scrubbing agent can embed into your saw and the two different metals in contact with each other can cause galvanic corrosion.
But make sure the saw is absolutely dry after washing.
If you are putting the saw away for a long time, you can protect it from rust by givning it a light coating of light oil (I use WD-40) – BUT REMEMBER TO ALWAYS WIPE OFF ALL OIL COMPLETELY BEFORE YOU PLAY – OIL WILL KILL YOU BOW!!!
If you want to really go crazy…. In nautical engineering, there is an item called a sacrificial anode. This is a peice of easily corrodable metal (typically, zinc) that you attach to the metal you want to protect. So a peice of zinc attached to a bronze condenser head will corrode quickly and by doing so will protect the condenser head. I dont want to go into details but suffice it to say, it works. You can do the same thing to protect your saw. Post US 1982 pennies are composed of zinc sandwiched between copper. To expose the zinc, stack up pennies on your drill press and bore a hole down the center. Next, get some copper wire and pass it through the holes and then wrap the wire around your saw.
A lot of effort to go through when it might be easier just to deal with the rust when it appears on your saw.
Possibly illegal – recently a law went into effect protecting pennies and nickles from mis-use (due to the fact that the mineral content is more valuable than the monetary value of these two coins)
The exercise is purely hypothetical – Ive never really tried it – but it should work!
Now, what to do when you discover rust:
Although this won’t do a perfect job in removing rust or blemishes – What I like to do is use emory paper or (non-metal) scouring pads with a little bit of oil to remove the rust – BUT PLEASE REMEMBER TO WIPE ALL OF THE OIL OFF THE BLADE BEFORE PLAYING.
The oil I use is WD-40 – but any light oil will work.
Any rust or blemishes on your saw are purely cosmetic and will in no way affect your music.
If you will be putting your saw away for any extended amount of time then it is a good idea to spray it with a coating of oil – but remember to remove the oil prior to playing. BUT REMEMBER TO ALWAYS WIPE OFF ALL OIL COMPLETELY BEFORE YOU PLAY – OIL WILL KILL YOU BOW!!!