My sanded brass inlays have turned white/silver

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sams93

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I have been making a project where I have set into some walnut some brass inlays. They started off as a single 1m long 1cm wide 2mm thick strip of brass, and then I cut them down with the bandsaw lengthways to give me a 1m long 0.5cm wide piece, then in half again to give me 4 pieces of 50cm x 0.5cm x 0.2cm of brass.

I set them into the piece leaving them slightly proud by maybe 0.5mm, as I planned to sand them to flush later.

They started off as a nice yellow colour, but after sanding they have turned to a bright white/silver colour.

It isn't the end of the world, but I wondered how I would get them back to the yellow colour they started. I sanded up to 600 grit.
 

PerryGunn

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The white will be oxidation of the brass, if you re-sand (or use wire wool) it'll disappear for a while then come back because the metal surface is exposed to the air.

To prevent it you need to seal the metal - wax will work but needs fairly frequent application, a clear lacquer will last longer
 

sams93

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Phill05

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Well it say's solid brass on the advert, when you make a saw cut through it can you see the bright brass colour or the white with a yellow coating round the edge.

I have worked with a lot of brass and never seen it go white naturally.
 

sams93

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F271C624-A477-4F28-9904-459B7685AD09.jpeg


47241598-DA73-4288-814F-B4007B5069C8.jpeg



It is solid brass, maybe it’s just brighter than I was expecting after sanding, it’s a real yellow in those pieces but on my piece it’s much brighter almost chromed
 

Droogs

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If they are solid brass, then it is down to 2 reasons. The first is that you have polished the surface with finer and finer grit making the surface more reflective and have also reduced the surface area you sea and therefore, you see less of the metal's colour and more of the reflected light.
 

PerryGunn

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Here's an example of white corrosion on brass
WhiteCorrosionOnBrass.jpg


I am not a metallurgist but, as I understand the process, brass is an alloy of Copper and Zinc and, depending on the composition of the brass, exposure to air can produce a thin surface layer of zinc oxide (which is white).
 

sams93

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If they are solid brass, then it is down to 2 reasons. The first is that you have polished the surface with finer and finer grit making the surface more reflective and have also reduced the surface area you sea and therefore, you see less of the metal's colour and more of the reflected light.
I think this is what has happened - It still had a slightly yellow tinge but was really reflective and so looked very bright and silvery. I have noticed that even over the past 24h since I did it that it has become more yellow in this short space of time, so I wonder if it will continue to yellow further over the next couple of days.
 

PerryGunn

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I don't think that's white - it just looks like diffuse reflection from the surface caused by the fine scratch lines left by the sanding. Perhaps you need to go through a couple of finer grades of sanding to produce a smoother surface and possibly finish with wire wool followed by a metal polish (I've never tried sanding brass so I don't know how fine you need to go)
 

Fergie 307

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I would agree with the last, 600 grit is actually quite coarse. Try something like 1500 or 2000 on one of your leftover bits and see what happens. I know on old rolled gold items, basically a sandwich of two thin layers of gold either side of a piece of brass, when the surface gold later wears away and you polish it up before plating it's hard to tell where the brass ends and the gold behind as it comes up such a rich yellow.
 

mikej460

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A long time back I polished the solid brass lever cap on my LN block plane using autosol (I know.. I know..) and it polished to an incredibly bright whitish colour but soon returned to a decent patina.
 

hunter27

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Unprotected brass soon dulls with age but is easy to brighten up with light abrasion. If it's to bright at the moment rub it with your fingers to tarnish it.
In an earlier life I used to clean old ship wreck port holes in acid and then finish them off a wire brush and lacquer them to keep them bright for wall mounting.
If you check with a magnet you will soon see if it's only brass plated.
 

Phill05

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Here's an example of white corrosion on brass
View attachment 136047

I am not a metallurgist but, as I understand the process, brass is an alloy of Copper and Zinc and, depending on the composition of the brass, exposure to air can produce a thin surface layer of zinc oxide (which is white).
I totally agree with you but and this is a big BUT your casing have years of neglect to get to that stage, the brass in question was new brass and clean cut and in all the brass I have in stock I have never seen that kind of corrosion.

Anyway looks like the problem has been solved and a fine chess board it has turned out to be well done sam93.
 

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