The Perils of BRASSO (and similar)

[Steven Tribe]

I am sure this brass polishing substance has many dear names around world - but this the version I know best from household use.

This is not about the evils of cleaning off character-giving patina or giving the brass a mirror finish far better than the original shop finish. No, this is about the previous owners (and perhaps their partners or domestic staff - think 1800’s!) not cleaning off excess cleaning liquid when the polishing is done. This liquid soon becomes a semi-solid paste and then a very tough layer in all sorts of difficult to access places.

I have bought quite a few lenses that had this pale blue residue in Waterhouse slots, around drive covers, inside lens hood, engraved texts etc. etc.

An example is shown below. This has the usual areas “covered” but in addition the whole rear cell has had its thread been completely completely blocked. This is probably a combination of a difficult thread to start with (this is from the period of hand cut threads), and a series of “Brasso” procedures through the ages.

The end result was a rear cell that would only go in about 1/2 its length and then come to dead stop. It took a couple of hours to clean out the threads using impregnating fluid, fine value grinding paste and hundreds of turns and releases to eventually clear out the threads. I have seen quite a few lenses where the cell won’t quite touch the barrel.

These early handcut threads in my experience are looser than modern threads and are held firm by the final twist which removes the “play”. If your threads are difficult, then it is a good idea to clean them before they lock up.

[Tin Can]

Only yesterday I watched a similar type warning about antibiotics and dangerous bacteria

The video showed a hospital worker cleaning a bed frame and never wiping the crevices

People are sloppy

We are near the top of the bell curve

[B.S.Kumar]

Steven, what kind of fluid do you recommend?

Thanks,
Kumar

[Two23]

I once bought a lens with the blue crap on it, and cleaned it off with a dental pick and hydrogen peroxide. I just thought it was corrosion. What lens is this, and when was it made?


Kent in SD

[Steven Tribe]

The lens is a Joseph Levy, London who existed for about a decade and eventually joined up with the Houghton/Butcher consolidation - like Zeiss-Ikon similar in Germany in 1926.

It is just a CdeV size and an obvious import from Gasc et Charconnet as it mimiks the very special French trademark.It is from 1865/66 because of details in the engraving.

One of my holiday duties was polishing up my Grandparents’ brass entrance name plaque, so I know all about BRASSO.

I used just a commercial penetrating fluid for the thread work and linseed oil and cotton buds for general clean-up of edges and corners.