Firstly I must agree with Leonid’s statement that you can only
achieve fine satin finishing after the item has been finished
correctly andbright polished, satin finishing or frosting will not
hide bad metal surfaces or save the effort of polishing, it is meant
to enhance the look of a surface not hide a bad surface. One of my
best workshopmachines is a Scratch Brush Unit, I tried searching for
a modern equivalent online and could only find one advert for a unit
by Walsh Tools here in the UK. The scratch brush unit is ideal for
adding a satin finish to metals, or even a frosted effectthat gives
a finishlike bright sand blasting. I tried a google search to see if
I could find a photo of this unit available worldwide and was
unsuccessful. I will attempt to explain thescratch brush assemblyand
how it works. The unit consists of a standard polishing motor mounted
behind a plastic box assembly with the polishing spindle point
facing the operator, the plastic box arrangement has water reservoir
on the top and a collection reservoir at the base, a small tap is
positioned above the spindle point, a brass scratch brush is screwed
onto the spindlepoint and the water tap is adjusted to allow a slow
flow of water onto the tips of the rotating brass brush. This process
explains why the brush is mounted with it’s flat edge facing the
operator, if it was as a usual polishing motor the operator would get
soaked when the brush rotated. When I was younger these machines
were regularly used by our silver polishers when polishing high
detail chasing work where normal polishing removes metal and detail,
a scratch brush shines without removing muchmetal, you could say it
is a mild burnishing effect. To achieve a frosted finish you would
use a long bristle brass mop and by holding a stick on the bristles,
breaking their flow,above that which you are frosting, this proces
causes the brass bristles to snap back and the tips of each
bristlewill frost the polished surface. A process much easier to show
than explain. I would hope that these unitsare available somewhere in
the USA and worldwidealso. When I was an apprentice, the scratch
brush units in our polishing workshop were all homemade units,
madewith wooden frames and plastic bowls, I could sketch a design if
anyone is interested. I have scanned a photo of a scratch brushing
unit, takenfrom an old Walsh Toolscatalogue, perhaps Hanuman would
be kind enough to make it available for anyone to view.
Peace and good health to all.
James Miller FIPG
