Exhibition soundbox - Cleaning

[Inigo]

Any kind soul knows how can one clean the backplate of an exhibition, so the black painting (or chemical treatment) doesn't go off? The only one I cleaned lost the blacking, so I ended polishing it to clean brass. Nice looking and perfect clean, but it lost its original appearance.
I would like to know how to clean another one without removing/spoiling the black finish, and also, if anyone can give some advice on how to apply a similar black finish to the one I polished to brass. I've read somewhere that it is a chemical blackening.

Thanks,

[JerryVan]

All I can say is, just be more gentle in your cleaning. If it hasn't already been removed by corrosion, the blackening does not come off that easily. You must have used an abrasive of some sort, such as a buffing wheel? Scouring powder? Metal polish? Just use soap & water, or maybe some lacquer thinner or other solvent. It's not necessary to get it looking brand new, spotlessly clean and shiny.

[Inigo]

I was ready to apply a small cotton dab with wd40. If it's so soft for being applied to 78s, it could do no harm on the backplate... I was going to test it in the part of the backplate that is covered by the rubber connector...

[Jerry B.]

It's a good suggestion to always start gentle and get more aggressive if needed. Jerry

[Henry]

Google "brass blackening" for products that do the job chemically.

[Inigo]

Colleagues, thanks for the tips. I'll tell later my results...

[VanEpsFan1914]

That about brass black is good stuff--never use paint on an Exhibition unless touching up the white engraved lettering, if you want to be period correct.

It ought to look nice after its restoration!

[Inigo]

This one I've bought from one of our colleagues, and is complete and in good shape.
I've tried cleaning the backplate with wd40 with a cotton dab, and it gets the back shiny and odorous, does no harm, and cleans softly. A little try with alcohol left the surface dull, but another application of wd40 restored the shiny feel. I ended washing it with soft natural soap, cold tap water and my hands, no scratching, and it cleaned well. The diaphragm had the usual stains and rests of the old rubber gaskets (hard and dried) and something that seemed lacquer, shellac or varnish, as if it had been stuck to the gasket using that varnish. Not alcohol neither solvent cleaned that. I've tried removing the stains using a very sharp blade knife, very carefully, but it didn't was easy, and the difficulty and delicacy of the work didn't satisfy me. Then I tried my small finger with a drop of my own saliva, and this cleaned it! After some digestive treatment, I ended with a final clean with my hands, scratching with my nail, and tap water and soft soap, and it cleaned marvelously. It's a good original mica diaphragm, well preserved, and it has a clean high clinking sound when dropped on the table one inch by its edge, held between the fingers at the bouncing. A definitely good test of a mica sound and integrity. The ones that sound dull will not work. The ones that sound as a thin cinking glass are good.
I've disassembled also the needlebar, for the springs were not in good position, and one of the support knife edges was stubbornly out of its engraved slot. One of the springs wasn't perpendicular to the plate, and clearly needed repositioning. A bit of force has placed it in the right square angle, and now the bar sits well on the two knives.
Tomorrow evening I will install new gaskets and try the soundbox for fine adjustment.

[Curt A]

When I made stained glass lamps and windows back in the '70s, it was necessary to tone down solder joints, brass pieces and lamp parts. Repairs to antique stained glass lamps and windows stand out like a sore thumb, without the correct aging materials. Phonograph reproducers and other parts which have been cleaned, often need some additional aging to blend back in. When using any of the three products listed below, it is important to clean the parts thoroughly and wipe them with alcohol to remove any oil residue, before applying the chemicals. Clean off all surface dirt and rust and buff them, if possible. Then age them back to an antique look without keeping all of the grunge... Use a Q Tip, clean cloth or paper towel to apply the product and leave it on until the desired effect is achieved. To stop the process from advancing further, spray the parts with gun lubricant or WD-40 and wipe off the excess.

I found several products that I consider to be indispensable for use with antiquing metals of all types. (1) Birchwood Casey Super Blue - works especially good on steel parts and I have had good success with brass as well... (2) Birchwood Casey Brass Black - the name says it all... and (3) Liver of Sulphur - very useful on brass, copper and bronze - it gives a more aged, antique patina appearance consistent with antique natural finishes. All three of these are available on Amazon.com and Super Blue is available in WalMart in the sporting goods section or at sports and gun shops. In my opinion, these are a mainstay in any restorer's toolbox.

[Inigo]

Curt, thanks for the details. The brass black will do the chemical blackening of this shiny brass backplate?

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