thanks guys, It looks like the link that Rusty sent sheds some light on my question. It looks like it's a copper zinc oxidation coating.
Last night I started to solder new parts onto the Geep 30's as well as re-attaching some suspect parts with some of PBL's high strength solder. When I clean up the parts on the duller brown finish they come out with the typical brighter brass color. Over the years I've noticed many of the Southwind/BTS parts are this color as well as, some old PFM C type engines. When either using a file or fine sandpaper the dull oxidation falls off in a fine dust. If any of you have these engines, I came across a new problem that I had to solve. I discovered that the roof of the cab is a fairly thick casting instead of the typical formed and etched brass sheet (that's the part that makes that engine so uniquely ugly!). I needed to attach a horn, UP style on the roof. Drilling the mounting hole took a lot longer but the kicker was using my resistance solding unit. I tinned the horn and tried several kinds of flux but the horn casting would get nearly red hot (near melting) without attaching to that heavy brass roof. So the horn casting was getting too hot while the roof casting wasn't even close apparently. I finally drilled a much larger hole about half way through the roof, then filled it with solder. I then drilled part of that out to where the horn could be positioned. Then the probe could melt the solder already in the hole. It's holding well now. I have to purchase some additional parts that I don't seem to have in stock, but after that I'll ship the engines off to be blasted in the back yard. I use baking soda for most of my work and some aluminum oxide when I need more aggressive action. Tonight I'll probably go back to working on wooden cabooses--will the fun never end! Bob Werre BobWphoto.com > > Go here: > > http://www.abbeyclock.com/brass.html > > It may or may not shed some light on the subject for you. What the > writer describes is almost the exact technique I use to clean brass > before painting. My photo supply shop is my good buddy for the > chemicals along with the cleaning supply outlet for the ammonia. One > last note. I know Samhongsa and SKI, SKI being the current builders > for Sunset, flash electroplated their models before final assembly > when they were selling models in a clear lacquer only. It makes them > all look a pretty shiny brass color. Today a lot of exporters black > oxidizes their models before painting, as in the Last Southwind > models. I seriously doubt it has anything to due with coal or oil, or > even who was the last person to touch them. > > J Rustermier > --- In [email protected] <mailto:S-Scale%40yahoogroups.com>, Bob > Werre <bob@...> wrote: > > > > I have a question that has been bugging me for some time. It doesn't > > seem to make any difference when working with brass...but there > seems to > > be two colors of the stuff. One color is a dull brownish bronze flavor > > while the other is the more common brighter 'golden' color. Why the > > difference? > > > > I've started to get my painting area cleaned up to work on several > types > > of brass trucks, plastic trucks, boxcar doors, and two brass Geep 30's. > > One of the 30's has a chassis that is this dull brown color while the > > rest of the engine is the lighter color. > > > > Bob Werre > > BobWphoto.com > > > > [Non-text portions of this message have been removed] ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/S-Scale/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/S-Scale/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
