1906 Rover

Something I hate to see are brass lamps that have been over polished. Over time continual polishing wears the brass away, especially on any edges, and gradually removes any lettering.  This process cannot be reversed.  Another problem with old brass starts in the manufacturing process which leaves stresses in the brass.  Eventually small stress-relieving cracks start and the formation of these can be greatly accelerated by acid corrosion.  Many brass cleaners contain mild acids so using them is likely to cause damage, like a wedge forcing the small cracks further apart.  I have found ways of dealing these problems.

Minor cracking can be arrested by annealing the area, then strengthening it by plating the underside, or by silver soldering with a low melting point solder.  Using phosphoric acid to clean the brass then washing it with soda to neutralize any acids left can help.  After doing that I use mild abrasives and polishing mops to get the desired finish.  I had to do a fair amount of work to my horn and rear light, the horn took two days, the lamp over a week.  After all that effort I wanted to preserve them in good order for the next generation.

Someone's attempt to repair the horn left it in a sorry state

I completely disassembled the horn

Finished horn (view 1)

Finished horn (view 2)

Polishing all the brass work on the car properly before we went to an event could take several hours, so I started to try to protect it with WD40.  This helped, but tarnish still crept back fairly quickly so regular cleaning was still necessary.  On my farm I used a dewatering rust preventative product on farm equipment, Ensis fluid.  This dried to a rather sticky varnish and would not have been suitable to apply directly to the lamps so I diluted it with hydraulic oil and paraffin.  Mixing these three in equal parts worked well and I found that after using it for some time the copper and brass took on a rather nice patina.  Dust and small insects do stick to the brass but wiping it with a cloth dampened in the solution removes this easily.  Once or twice a year I clean it all off with paraffin and apply a fresh coat.  If you want a highly polished look for a special occasion this is easier to achieve.

Patina on the copper

Patina on the copper

After using this formula for some while I discovered an added benefit, it had stopped the continued corrosion in small pits that I had been unable to remove before.  Looking at the spec. sheets for Ensis fluid recently I discovered that it contains an acid inhibitor.  Several other people have now tried my formula and have been pleased with the results.

Repairs complete, some polishing still to do.

Finished lamps