I know this isn't exactly land surveying, but I hope Wendell will forgive me so that as many as possible can see and learn.
At any rate, a friend brought his compass to me to do some work on it. Specifically to re-silver plate the face because someone in the past tried to polish it and took all the silver off.
So when I do this type of service I need to completely disassemble the instrument. When I took this compass apart I found that whoever tried to clean it used Brasso and as will happen it oozed into all the nooks and crannies. When that happens it just sits there and eats away at the metal.
The following picture shows the area between the main plate and the compass ring after years of Brasso corrosion building up.
So, if you insist on cleaning an instrument - DO NOT USE BRASSO! Or better yet, let someone who knows what they are doing do it after discussing with them what end results you want.
Every time something metal is cleaned, metal is being removed. Brasso and simichrome are great for bringing out shine but shouldn't be used on anything other than decorations...
Happich Simichrome
Simichrome (like Brasso) is a wonderful compound for aluminum side and case plates for motorsickles and the like. Just like the photo of the brass compass collar, it becomes caustic if not removed.
I don't know how many shiny, shiny aluminum primary covers I've seen at motorcycle shows that look like mirrors...but...a close inspection will reveal the compound migrated into the crack between the mating surfaces. And owners wonder why they leak oil.
"Polishing" anything should require removal of the piece, with careful cleaning afterwards, before reassembly. Shiny doesn't really mean much..clean means a lot.
Thank you for this post as I would have used semichrome. We do kind of need a DIY area
Whenever I need brass, copper, or bronze cleaned, I use ketchup. I would not use it on a surveying instrument but it does wonders on ordinary items. Smear a heavy dose of ketchup, let sit overnight and the next morning the ketchup will be green because it pulled out the oxidation. Wipe off and apply another layer of ketchup. No chemicals, no gloves, that simple.
> No chemicals
I consider citric acid, malic acid and acetic acid to be chemicals. How about "no unsafe concentrations of chemicals"?
toothpaste
Toothpaste makes a good polishing compound that is water soluble and rinses fairly clean. Imagine how well your cherished M1911 will shoot when it's minty clean!
toothpaste
:good: :good: :good:
I Agree, Jim.B-)